G R E E N H O U S EPESTICIDEM A N A G E M E N TPrivate Pesticide Applicator Training Manual: Greenhouse

This publication is pro-duced through the com-bined efforts and resourcesof the Cooperative Exten-sion organizations of theNew England Land-GrantUniversities

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Pesticide Applicator Training Manual: Private Greenhouse

GREENHOUSEPESTICIDEMANAGEMENT

Ed i t ed by D . W. Barry

Univers i t y o f Maine Coopera t i ve Ex tens ion

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CONTRIBUTORSUniversity of Connecticut Candace Bartholomew

Leanne PundtConnecticut Department ofEnvironmental Protection Linda SchmidtUniversity of Maine Jim Dill

Lois StackMaine Department of Agriculture Richard Folsom

Anne GibbsGrace O'Keefe

Maine Board of Pesticides Control Gary FishTammy Gould

University of Massachusetts Natalia CliftonPat VittumTina Smith

University of New Hampshire Cheryl SmithStan Swier

New Hampshire Departmentof Agriculture Wendy ChapleyUniversity of Rhode Island Steve Alm

Peggy SiligatoUniversity of Vermont Anne Hazelrig

Published and distributed in furtherance of Acts of Congress of May 8 and June 30, 1914 by Cooperative Exten-sion; the United States Department of Agriculture, the following Extension Services and Land Grant Universities co-operating:

Kirklyn Kerr, Director, Cooperative Extension System, University of Connecticut, Storrs, CT 06268

Lavon L. Bartel, Director, Cooperative Extension, University of Maine, Orono, ME 04469

John Gerber, Director, Cooperative Extension Service, University of Massachusetts, Amherst, MA 01003

Peter J. Horne, Director, Cooperative Extension Service, University of New Hampshire, Durham, NH 03824

Robert H. Miller, Director, Cooperative Extension Service, University of Rhode Island, Kingston, RI 02881

Lawrence K. Forcier, Director, University of Vermont Extension System, Burlington, VT 05405

Cooperative Extension provides equal opportunities in programs and employment. In complying with the letter andspirit of applicable laws and in pursuing their own goals of pluralism, these Universities shall not discriminate on thegrounds of race, color, religion, sex, sexual orientation, national origin or citizenship status, age, disability, or veteransstatus in employment, education, and all other areas of each University. These Universities provide reasonable accom-modations to qualified individuals with disabilities upon request.

Questions and complaints about discrimination in any area of these Universities should be directed to the Directorof Equal Opportunity. Inquiries about discrimination may also be referred to your state Human Rights Commission, U. S.Equal Employment Opportunity Commission, Office for Civil Rights of the U. S. Department of Education, or otherappropriate federal or state agencies.

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ACKNOWLEDGMENTS

The following publications were valuable sourcesof information and illustrations:

“1992-1993 New England Floriculture Crop PestManagement and Growth Regulation Guide” edited byL. P. Perry, University of Vermont Cooperative Ex-tension and L. B. Stack, University of Maine Coopera-tive Extension.

"Controlling Damping-off diseases in the Garden,"S. A. Tjosvold, University of California CooperativeExtension.

"Diseases of Ornamental Plants," Junius Forsberg,University of Illinois.

"Floriculture Production Guide for CommercialGrowers," edited by Christine Koch, B.C. Ministry ofAgriculture, Fisheries, and Food, 1994-95 ed.

"Insect and Related Pests of Flowers and FoliagePlants" edited by J. R. Baker, University of North Caro-lina Cooperative Extension.

"IPM for Poinsettias in New York: A Scouting andPest Management Guide" Edited by G. Ferrentino, J.Grant, M. Heinmiller, J. Sanderson, and M. Daughtrey.Cornell Cooperative Extension, Cornell University.

"Morphological Comparisons of Three Species ofWhiteflies Found on Greenhouse-Grown Plants," Tong-Xian Liu and R. D. Oetting, University of GeorgiaResearch Bulletin Number 412.

“Pesticide Applicator Training Manual for PrivateApplicators in the Greenhouse and Florist Industries,”Cornell Cooperative Extension.

"Suppliers of Beneficial Organisms," Charles D.Hunter, California Environmental Protection Agency,Department of Pesticide Regulation, EnvironmentalMonitoring and Pest Management Branch, 1994 ed.

Production of this manual was made possiblethrough a grant from the United States Department ofAgriculture.

PRECAUTIONS

Follow directions on chemical labels. Timingand proper sprayer calibration are as important asthe product used.

Cooperative Extension makes no warranty or guar-antee of any kind, expressed or implied, concerningthe use of any of the stated products. Users assume allrisk of application and/or handling, whether they fol-lows recommendations or not. Trade names are usedfor identification only; no product endorsement is im-plied, nor is discrimination intended

First publication date, Fall 1996

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PREFACE

This manual has been edited by the Pesticide Appli-cator Training Program to serve as a study guide forprivate pesticide applicators whose primary productionis greenhouse crops. It explains how to apply pesticidessafely and effectively and how these applications mayaffect you, your family, your neighbors and your cus-tomers. It also describes the state and federal laws thatregulate pesticide use and provide for worker safety. Thisinformation will help you prepare for the state certifica-tion examination.

Use this manual with your state Core Manual. Thatvolume contains a glossary of pesticide related terms. Italso has a section on mathematical conversions and cal-culations that will be useful when calibrating equipmentand determining the proper quantities of pesticides toapply.

In order to become certified, you must pass twotests: one based on the information in the Core Manualand another based on this manual. Both the Core Manualand “Greenhouse Pesticide Management” are self-studyguides. You control the pace of your learning. After read-ing each section, try to answer the review questions.These questions are similar to those found on the certifi-cation exams. Correct answers are found at the end ofthe manual. If you have difficulty with a certain area, goback and review that topic. Allow yourself adequate timeto read and understand the material before you take theexams.

After completing the exam, keep this manual as ageneral reference on pest identification and managementstrategies. It is impossible to include pesticide recom-mendations in this type of manual due to new chemi-cals, label changes, and regulatory actions. Those pesti-cides that are mentioned are only examples and shouldnot be considered either endorsements or recommenda-tions. For specific pesticide recommendations see thelatest edition of the "New England Greenhouse Floricul-tural Recommendations, A Management Guide for In-sects, Diseases, Weeds and Growth Regulators" avail-able through Cooperative Extension.

SECTION 1GREENHOUSE OPERATION AND PESTICIDE

REGULATION

GREENHOUSE PRODUCTION 1CHEMICAL PEST CONTROLS 2PESTICIDE REGULATION 3

SECTION 2WORKER AND CONSUMER SAFETY ISSUES

APPLICATOR SAFETY 6WORKER PROTECTION STANDARDS 7CONSUMER PROTECTION 12

SECTION 3ENVIRONMENTAL PROTECTION ISSUES

POLLUTION FROM GREENHOUSES 15STORAGE AND DISPOSAL 17ENVIRONMENTAL REGULATIONS 18

SECTION 4GREENHOUSE IPM

INTEGRATED PEST MANAGEMENT 20IPM TECHNIQUES 20CONTROL METHODS 23CULTURAL PRACTICES 24MECHANICAL METHODS 25BIOLOGICAL CONTROLS 25CHEMICAL CONTROLS 26

SECTION 5PESTICIDES FOR GREENHOUSE PRODUCTION

SELECTING A PESTICIDE 30COMMON GREENHOUSE PESTICIDES 31ADJUVANTS 32PROPER HANDLING OF PESTICIDES 32SPILL CLEAN-UP AND REPORTING 33

CONTENTS

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SECTION 6EQUIPMENT AND CALIBRATION

GREENHOUSE SPRAYERS 36SPRAYER COMPONENTS 40CHEMIGATION 41CALIBRATION 41CLEANING AND MAINTENANCE 44

SECTION 7FUMIGATION

FUMIGANTS 46FUMIGATION WITH METHYL BROMIDE 48

SECTION 8THE GREENHOUSE ENVIRONMENT

ABIOTIC DISORDERS 52TEMPERATURE 52LIGHT 53WATER 53PLANT NUTRIENTS 55IMPORTANCE OF pH 58FERTILIZATION PROGRAMS 59AIR 60POLLUTION 61PESTICIDE INJURY TO PLANTS 62MECHANICAL INJURY 62

SECTION 9GREENHOUSE PESTS

APHIDS 65MITES 67WHITEFLIES 69SCALES AND MEALYBUGS 71THRIPS 74LEAFMINERS 76CATERPILLARS 76FUNGUS GNATS & SHORE FLIES 77NEMATODES 78

SECTION 10MANAGEMENT OF GREENHOUSE DISEASES

DAMPING-OFF 83LEAF SPOTS, FLOWER SPOTS AND BLIGHTS 84WILT DISEASES 85ROOT ROTS 86BOTRYTIS (GREY MOLD) 88POWDERY MILDEW 89DOWNY MILDEW 89RUSTS 89BACTERIAL DISEASES 90VIRAL DISEASES 92

SECTION 11GREENHOUSE WEED MANAGEMENT

REASONS FOR WEED CONTROL 99WEEDS OUTSIDE THE GREENHOUSE 99WEEDS INSIDE THE GREENHOUSE 100ALGAE 100

APPENDIX AGREENHOUSE REFERENCES

PRODUCTION REFERENCES 102FLORICULTURAL ASSOCIATIONS 103JOURNALS 104INTERNET RESOURCES 104OTHER INFORMATION SOURCES 104COOPERATIVE EXTENSION OFFICES 104

APPENDIX BBIOLOGICAL CONTROL

DIRECTORY OF BENEFICIAL ORGANISMS 106

APPENDIX CANSWERS TO REVIEW QUESTIONS

ANSWERS TO REVIEW QUESTIONS 125

CONTENTS

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Several government agencies regulate the pesticidesused in greenhouse production in order to protect boththe environment and the health of workers and custom-ers. This section introduces the principal laws regulat-ing pesticides manufacture and use. Requirements forcertification and licensing of applicators are provided,including:

Who must be certified,

Why applicators must be certified,

What knowledge is required for certification,

How to become certified and licensed, and

How to maintain certification and licensing.

GREENHOUSE PRODUCTION

Greenhouse operation is an important part ofConnecticut's economy and way of life. Many flowersthat grace window boxes in summer or fresh vegetablesgathered from gardens started in greenhouses during coldspring months.

There are 525 commercial greenhouses in Connecti-cut covering 8 million square feet of production area.Many are small, seasonal operations that provide onlysupplemental income for growers but many have grow-ing areas greater than 10,000 square feet. The produc-tion of bedding plants is a major crop for greenhouseoperators of all sizes. The annual sales of bedding plantsfrom Connecticut's greenhouses is $130 million. Larger

producers may also grow potted flowering and foliageplants, cut flowers, and vegetable crops.

The controlled greenhouse environment provides alevel of management not possible in field-grown crops.Most factors that affect plant growth, such as soil fertil-ity and available moisture, are easily monitored and ad-justed to promote vigorous, healthy plants. Greenhousesalso provide ideal conditions for the spread of somediseases and insects, making pest control an essentialpart of production.

Crop production and public welfare

Although profit is the primary goal for greenhousecrop production, there are other considerations that de-mand attention. Greenhouse producers are increasinglyasked to ensure the safety of their production activities.Public expectations include:

Offering products that present no health risks toconsumers,Providing for worker protection, andAvoiding environmental contamination frompesticide use.

Putting these goals into practice demonstrates aware-ness and concern for public welfare. It is difficult orimpossible, however, to control the effects of manage-ment practices that fall into the following categories:

Distant effects - such as a consumer purchasingplants from a retail outlet rather than the produc-tion greenhouse;Delayed effects - such as a greenhouse employeewho becomes ill long after pesticide exposure;Invisible effects - such as pesticides leachingthrough soil and contaminating groundwater.

Most state and federal pesticide regulations areenacted to protect human health and our environment.Knowing and complying with these laws not only mini-mizes pesticide problems, but may actually increase prof-itability and improve public opinion. Therefore, com-

GREENHOUSE OPERATIONAND PESTICIDE REGULATION

SECTION 1

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Alternative controls

In certain crops, biological controls may substantiallyreduce pesticide use. An example uses the tiny parasiticwasp, Encarsia formosa, to attack greenhouse white-fly. This technique may be slower but ultimately aseffective as any pesticide application. Other alterna-tives include cultural controls, such as wider plant spac-ing to inhibit fungal disease, and mechanical controlslike roguing (removing) diseased plants. Even for grow-ers who use only chemical control, alternative applica-tion equipment is available that reduces the requiredamount of active ingredient. In addition, choosing spe-cific pesticides to control specific pest growth stageswill reduce pesticide use. Using a variety of techniques that maximize the af-fect of pesticides and maintain crop quality is calledINTEGRATED PEST MANAGEMENT (IPM). Thegeneral principles of IPM should be incorporated intocrop management plans. IPM promotes wise pest con-trol using a combination of cultural, mechanical, bio-logical and chemical methods. Federal and state agen-cies, grower organizations and private consultants co-operate in supporting IPM programs. Contact yourcounty Cooperative Extension office or the ExtensionSpecialists at UNH for the most recent information onthese programs. A general introduction to IPM prac-tices is provided in Section 4.

CHEMICAL PEST CONTROLS

Pest control has changed a good deal over the last50 years. Early methods relied on labor-intensive cul-tural practices. The few chemicals available were dan-gerous to use and often ineffective. Beginning in the1940s, development of synthetic chemical pesticidesprovided hope of ending pest problems once and for all.However, this hope was short lived. Soon after wide-spread, intensive use of these new compounds, certain

pliance with the law is fundamentally important to green-house production.

Developing a crop management plan

Successful marketing depends on the production ofquality plants free from signs of pests and disease. De-veloping a crop management plan before the beginningof a growing cycle will help meet this goal. Theseplans include how to control insect infestation and plantdisease and give growers the opportunity to considerboth benefits and risks of the available practices beforeactually using them. An effective management plan notonly reduces the environmental risks associated withpesticide use but saves time and money.

Good crop management limits the need for pesti-cides by encouraging the growth of vigorous, healthyplants. Some of the factors that promote plant growthand discourage pest problems are:

Keeping the greenhouse and all systems in goodrepair,Selecting crops suitable for the growing condi-tions provided,Selecting varieties with pest resistance, whenavailable,Maintaining good environmental conditions inthe greenhouse,Proper timing of planting and other productionactivities, andUsing alternative pest management techniquesincluding cultural, mechanical and biologicalcontrol.

Although this manual provides information on theproper use of pesticides when they are required, it can-not provide complete information on greenhouse opera-tion. Many references are available covering greenhouseconstruction and crop production. A few are listed inAppendix A. The current edition of New England Flo-ricultural Crop Pest Management and Growth Regula-tion Guide is available through the University of Con-necticut, Communications and Information Technology,1376 Storrs Road, Storrs, CT 06269-4035, (860) 486-3336. This guide is updated biennially and provides in-formation on products and application rates that areFederally registered for greenhouse use. For informa-tion about products registered for use in greenhousescontact your county or university Cooperative Exten-sion office (see Appendix A) or the Department of En-vironmental Protection (DEP), Pesticide ManagementDivision (860) 424-3369.

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compounds derived from natural sources. Pesticide in-jury may result from:

Direct contact with pesticides during handling orapplication;Indirect contact from residues following anapplication; orIndirect contact through contaminated naturalresources, such as treated soils or pollutedwater.

The persons most likely to be harmed by exposure topest control chemicals are the applicators themselvesduring pesticide use. However, the chemicals currentlyregistered should not cause adverse effects when usedaccording to label directions. Specific regulations havebeen developed to protect the health of applicators andfarm workers. These include procedures that must befollowed when handling, mixing and applying pesticides. Careful choice of products and timely applicationshelp reduce the risks associated with pesticide use. Ap-plicators should be aware of these personal and envi-ronmental hazards and limit risks by handling all prod-ucts according to label directions. Information pro-vided on labels is the primary means of regulatingpesticides.

PESTICIDE REGULATION

The EPA has the authority to regulate the pesticideindustry under the Federal Insecticide, Fungicide andRodenticide Act (FIFRA). This law permits the controlof all aspects of pesticide use, from production throughthe disposal of empty containers. In Connecticut chemi-cal use is supervised by the Connecticurt Departmentof Environmental Protection. General information on federal and state laws cov-ering the use and storage of pesticides is found in yourState Pesticide Applicator Training (Core) Manual. Manyof these laws help greenhouse operators develop lowrisk and effective application programs. For example,record keeping requirements make it possible to com-

insects and diseases developed resistance to the theireffect. Continued application of these products pro-vided little control but substantially increased produc-tion costs and resistance problems. Chemical pesticides may also lead to environmentaldamage although the effects may go unobserved foryears. Following widespread use of pesticides duringthe 1950s, it became apparent that some of them causedserious harm to nontarget organisms such as birds, fishand beneficial insects. Chemicals that persisted in theenvironment, like DDT, were particularly harmful. Nowproducts registered for pest control are regularly reviewedin an effort to reduce undesirable effects.

Pesticides and public safety

Pesticides and public safety is an increasingly im-portant consumer issue. In recent years, concern overpesticide residues on consumer products and ground-water contamination has received national attention.Proper selection and use of pesticides will generally pre-vent residues from exceeding federal limits. This is es-pecially important for businesses that allow customersinto greenhouses when marketing crops. Pesticides mustbe carefully chosen and applied to avoid unacceptableresidues on all crops at the time they are sold. Remem-ber that certain types of plants may actually retain chemi-cal residues. Groundwater quality is a growing concern through-out the country. As a pesticide applicator you shouldknow that groundwater contamination may be causedby pesticide spills, incorrect applications or improperdisposal methods. Even correctly applied chemicals usedover long periods may leach through the soil and entergroundwater. This can easily occur in many of the typesof soils that are found throughout Connecticut.

Pesticides are poisons designed to kill a narrow se-lection of living organisms. In addition to controllingthese target pests, pesticides may also, unfortunately,injure or kill nontarget plants and animals, including hu-mans. This is true of synthetic pesticides as well as

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pare results over several seasons and provide useful evi-dence in the event of legal action. Every pesticide ap-plicator is responsible for knowing and complying withall appropriate pesticide laws.

Classification of pesticide products

Toxicological studies performed by chemical compa-nies during product development determine the classifi-cation of each pesticide. The EPA classifies pesticidesas either GENERAL USE or RESTRICTED USE.Anyone applying general use or restricted use pesticides,which include certain products used in greenhouse pro-duction, must meet the standards set by the EPA andthe DEP. Anyone applying restricted use pesticides mustbe licensed, or under the direct supervision of someonewho is licensed. In Connecticut, a third class, PERMIT-TED USE pesticides, is recognized which requires aspecial permit for each use. The DEP requires certifica-tion and licensing of persons using restricted use pesti-cides and those making commercial applications of anypesticide.

Applicator Certification

Pesticide applicators who become certified mustsuccessfully demonstrate the competency requirementsspecified by state law. A private applicator is an indi-vidual who uses or supervises the use of any pesticides,whether classified as general use or state restricted use,for purposes of producing any agricultural commodityon property owned or rented by them or their employeror, if applied without compensation other than trading ofpersonal services between producers of agricultural com-modities, on the property of another person. Ask yourCooperative Extension for more information.

The DEP uses written exams to determine the quali-fications of persons seeking certification as private ap-plicators for greenhouse applications. The GreenhousePesticide Management Manual, when used with the CoreManual, provides the technical information needed toprepare for the private applicator exams. Sample ques-tions at the end of each section are similar to those onthe written exams. Be sure to know and understand theanswers to these questions before taking the written ex-ams. Certification for private applicators is for up to a five-year period, during which time twelve (12) recertificationcredits must be accumulated. Participating in recertifi-cation sessions is also a means of keeping up-to-datewith the changes that affect greenhouse production. Re-

certification programs are offered by the University ofConnecticut Cooperative Extension Service (CES), theDEP, growers’ organizations and other sources.

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1. Crop management plans give growers the oppor-tunity to consider both benefits and risks of avail-able practices before actually using them.

________True ________False

2. Which factors promote plant growth and discour-age pest problems?

a. Selecting pest resistant plant varietiesb. Maintaining good environmental conditions in the

greenhousec. Using cultural, mechanical and biological con-

trolsd. All of these

3. The New England Floricultural Crop Pest Man-agement and Growth Regulation Guide providesinformation on crop management products and ap-plication rates.

________True ________False

4. List three non-chemical pest control alternatives.

a.

b.

c.

5. Integrated Pest Management (IPM) involves us-ing a variety of pest control techniques that maxi-mize the effect of pesticides and maintain cropquality.

________True ________False

6. Widespread, intensive use of synthetic pesticidesin the 1940’s and 50’s led to insect and diseaseresistance to these controls.

________True ________False

7. Groundwater contamination may be caused by:

a. Pesticide spillsb. Incorrect application of pesticidesc. Correct application of pesticidesd. All of these

8. Pesticide injury could result from contact withtreated potting soil.

________True ________False

SECTION 1- REVIEW QUESTIONS

Greenhouse Operation and Pesticide Regulation

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APPLICATOR SAFETY

Greenhouse pesticide use requires strict attention tosafety measures. Two aspects of the greenhouseenvironment directly affect the safety of pesticideapplicators:

(1) Frequent application - Greenhouses produce plantsyear-round confined in a warm, sheltered area. Theseideal conditions can attract pest populations and createthe need for frequent pest control.

(2) Enclosed design - Greenhouses enclose space andcarefully regulate air flow. During typical pesticideapplications, all ventilation within the house is stopped.This minimal air movement hinders pesticide dispersaland harmful levels may concentrate within greenhouseair.

Pesticide applicators should know these points andunderstand how they increase risk. At this point it willbe helpful to review your Core Manual for a discussionof pesticide exposure and personal protective clothingand equipment.

Inhalation exposure and protection

Pesticide application in an enclosed greenhouse isvery different from treatments in the open air. In thegreenhouse, pesticides not only dissipate slowly, but,without wind or air turbulence, they may actuallyconcentrate to dangerous levels.

Because continuous pesticide exposure throughinhalation is a major risk, a respirator is requiredwhenever a pesticide applicator or handler is in thegreenhouse during treatment. Remember, even thoughamounts are small or the pesticides are only slightly toxic,repeated contact with pesticides increases the risk ofoverexposure. Review the section on respirators in yourCore Manual.

Dermal exposure and protection

During control treatments, applicators can accumulateconsiderable skin (dermal) and eye (ocular) contact withpesticides. Contact occurs when applicators brush againstplants and other treated surfaces, or by walking throughthe pesticide mist which tends to linger in the still air, orfrom falling spray droplets and dripping overheadbaskets.

Examples of clothing requirements found on pesticidelabels include:

Personal protective equipment must be worn everytime an applicator applies pesticides inside agreenhouse. Read the pesticide label for specificinstructions.

The eyes must be covered either with chemicalsplash goggles or a full face respirator.

The head and neck must be protected. Usechemical-resistant rain hats, or washable hard hatsand hooded chemical resistant spray suits.

SECTION 2

WORKER AND CONSUMERSAFETY ISSUES

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Cover the arms, body and legs with a chemicalresistant suit. Do not use cotton coveralls.They do not provide adequate protection forgreenhouse applicators.

Wear unlined, chemical-resistant boots that coverthe ankles.

Wear chemical-resistant gloves.

Clean all personal protective equipment after eachuse and store in a clean uncontaminated area.

Launder garments, including undergarments at theend of each work day. Because most materials willaccumulate pesticide residues over time, youshould replace gloves, boots and suits periodically.

In addition to personal protective equipment, thereare a few application practices that will reduce the riskof accidental poisoning:

Many labels require that you take down hangingplants for treatment, do not spray over your head ifit can be avoided.

Do not use highly toxic pesticides (like aldicarb) forhanging baskets.

If you must apply over your head, treat plants inthe aisle next to you, rather than the plants directlyover your head. This way you are to the side of theapplication.

Apply the pesticide while backing away from theapplication.

Be informed of available pest managementalternatives, and use the least toxic method.

WORKER PROTECTION STANDARDSFOR GREENHOUSES

The EPA Worker Protection Standard (WPS)regulates activities of greenhouse employers, pesticidehandlers and other workers to reduce the possibility ofpesticide exposure. Requirements of the WPS have beenin place since January 1, 1995. These requirements aresummarized here. For more information, contact yourCooperative Extension or the DEP.

GREENHOUSE is defined as any operation thatproduces agricultural plants indoors in an area that isenclosed with nonporous covering and that is largeenough to allow a person to enter. Examples includepolyhouses, mushroom houses and caves, and rhubarbhouses, as well as traditional greenhouses. Malls, atriums,conservatories, arboretums, and office buildings thatgrow or maintain plants primarily for decorative orenvironmental benefits are not included.

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Handlers working with fumigants must be in constantvisual or voice communication with another trainedhandler who monitors the application.

WORKER is defined as anyone who: (1) is employed(including self-employed) for any type of compensationand (2) is doing tasks, such as harvesting, weeding, orwatering, relating to the production of agricultural plantson a farm, forest, nursery, or greenhouse. This termdoes NOT include persons who are employed by acommercial establishment to perfrom tasks such as cropadvisors.

All employers must establish an information area ata central location that displays the EPA WPS safetyposter and complete medical emergency information.Facts about all pesticide applications must be postedfrom just before they are made until 30 days after therestricted-entry interval (REI) ends. Greenhouse entryrestrictions for workers and handlers depend on the typeof pesticides and application methods used - see charton following page.

Employers must provide handlers with adecontamination site consisting of adequate clean waterto wash the entire body, soap, disposable, single-usetowels and one clean change of clothes. At least threegallons of clean water should be supplied for eachhandler. Workers must also have access to a similardecontamination site except that a change of clothes isnot required.

Employers must provide pesticide safety training forhandlers and workers every five years unless they arealready licensed applicators. Training may only be doneby a certified applicator, a person designated by the statepesticide lead agency, a person who has completed atrain-the-trainer class, or, in the case of workers, a trainedhandler. Training must be given in a languageunderstandable to the employees. These requirementsmay vary from state to state.

Employers must provide handlers with, at least, theamount of personal protective equipment (PPE) requiredon the pesticide label. Employers must ensure thatprotective clothing and equipment is clean and intact,fits properly, and is in good operating condition.Employers must also ensure protective clothing andequipment is used correctly. No handler may wear ortake pesticide-contaminated personal protectiveequipment away from the job site or employer’s facility.

AGRICULTURAL EMPLOYER is defined asanyone who employs or contracts for the services ofworkers (including themselves and members of theirfamilies) for any type of compenstion to perform tasksrelated to the production of agricultural plants or, whoowns or operates an agricultural establishment that usessuch workers.

PESTICIDE HANDLER is defined as anyone who:(1) is employed (including self-employed) for any typeof compensation by an agricultural establishment or acommercial pesticide handling establishment that usespesticides in the production of agricultural plants on afarm, forest, nursery, or greenhouse, and (2) is doingany of the following tasks:

mixing, loading, transferring, or applyingpesticides,

handling opened containers of pesticides,

acting as a flagger,

cleaning, handling, adjusting, or repairing theparts of mixing, loading, or applicationequipment that may contain pesticide residues,

assisting with the application of pesticides,including incorporating the pesticide into the soilafter the application has occurred,

entering a greenhouse or other enclosed area afterapplication and before the inhalation exposurelevel listed on the product labeling has beenreached or one of the WPS ventilation criteriahas been met to:

operate ventilation equipment

adjust or remove coverings, such as tarps,used in fumigation, or

check air concentration levels,

performing tasks as a crop advisor:

during any pesticide application,

before any inhalation exposure level orventilation criteria listed in the labelinghas been reached or one of the WPSventilation criteria has been met,

during any restricted-entry interval,

disposing of pesticides or pesticide containers

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10

WPS Questions and Answers for GreenhouseOperators

Q: l’m treating only a few benches in my greenhousewith a hand sprayer. Do I need to post signs? If so,where do I post them?

A: All pesticide applications in greenhouses must be postedwith one or more WPS warning signs. Because only afew benches were treated with a non-powered handsprayer, you have a choice about sign placement. Warn-ing signs can be placed on the entrance to the green-house. This would prohibit workers from the entire green-house. Warning signs can also be placed on the cornersof benches or in aisles, designating a smaller area withinthe greenhouse in which workers are prohibited. In somesituations small warning signs may even be placed inindividual pots to warn workers about pesticide applica-tions. Each employer must determine what is acceptablefor their situation based on total area treated in the green-house and anticipated worker tasks

Q: I am treating several benches in a large green-house with a pesticide which requires me to wear arespirator. The restricted entry interval (REI) is 12hours. When can workers go in and work with plantson the other benches?

A: When a pesticide is applied which requires the appli-cator to wear a respirator, workers, customers and mem-bers of the public, must stay out of the entire enclosedarea of the greenhouse until ventilation criteria are met.Suitable ventilation is accomplished in one of severalways in a greenhouse:

- 10 air exchanges, or

- 2 hours of ventilation using fans or other mechanical ventilating systems, or

- 4 hours of ventilation using vents, windows or other passive ventilation, or

- 11 hours with no ventilation followed by 1 hour of mechanical ventilation, or

- 11 hours with no ventilation followed by 2 hours of passive ventilation, or

- 24 hours with no ventilation.

If ventilation is accomplished before the expiration ofthe REI, workers only are prohibited from contactingplants on the treated benches for the duration of theREI. If ventilation takes longer than the REI, then work-ers are free to work with all plants once criteria are met.

Q: When I applied a pesticide this morning in mygreenhouse, the weather forecast was for a cloudy,cool day. The clouds have cleared and the sun isout. I’m worried that I will lose my plants if I don’twater them, but the restricted entry interval is 12hours. What can I do?

A: Entry to a greenhouse during the REI to water plantsis normally prohibited, however, there are some excep-tions for this type of emergency situation. First, workersmay enter after any ventilation criteria have been met towater plants providing they have no contact with any-thing treated with pesticide. For example, workers couldeasily water seedlings in starter trays without contactingthe treated matter. Workers are also allowed to enter tooperate or move watering equipment under the limitedcontact exception. This exception provides for thoseunforeseen tasks which cannot be delayed without sig-nificant economic loss. An employer is required to pro-vide a number of protections to workers under this ex-ception including personal protective equipment and spe-cial training. Worker time in the area under restrictedentry is also limited.

Q: I recently purchased some pesticides without WPSrequirements on the label. Do I need to comply?

A: All agricultural pesticides now in the marketplace mustbear WPS labeling. If you have recently purchased aproduct to use in your greenhouse which does not con-tain WPS language, then check the product label andmake sure it has directions for use in a greenhouse. Allpesticides used in greenhouses must specifically men-tion “greenhouse” on the label. Home and garden pesti-cide products should not be used in greenhouses be-cause they neither mention greenhouses on the label norcontain WPS language.

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Sign Size and Posting Minimum Requirements

Circle graphic DANGER & PELIGRO Other lettering Posting height lettering height height Distance

7"X 8" 3" 7/8" ½" 50 feet

4 ½"X 5" 1 ½" 7/16" ¼" 25 feet

Worker Protect ion Warning Signs

In September 1995, EPA proposed to allow grow-ers to substitute another language for the Spanish por-tion of the warning sign and to allow the use of a smallsize sign in nurseries and greenhouses where use of thestandard (14"X16") sign interfered with operations andthe clear identification of a treated area. EPA consid-ered the comments received from growers, farmworkergroups, state agencies, and private citizens and amendedthe rule, in June 1996, to allow other languages to im-prove the effectiveness of the signs in warning workerswhose predominant language is not Spanish and to per-mit smaller signs in greenhouses and nurseries. The En-glish/Spanish warning sign is pictured below.

Summary of the Final Rule Amendment

Allows substitution of the language commonlyspoken and read by workers for the Spanish por-tion of the warning sign. The sign must be in theformat required by the WPS and be visible andlegible. Use of alternative languages is optionaland continued use of English/Spanish sign is al-ways acceptable.

Allows use of smaller signs provided minimum let-ter size and posting distances are observed. In nurs-eries and greenhouses, small signs may be used anytime. A small sign may be used on farms and for-ests if the treated area is too small to accommodatethe standard sign.

Language substitution on the sign allows agricul-tural employers to tailor the sign to accommodatea work force whose predominant language is nei-ther English nor Spanish. Allowing smaller signsin nurseries and greenhouses will facilitate postingof treated areas. The posting and lettering require-ments for the smaller signs will result in sign sizesof approximately 7 inches by 8 inches and 4½inches by 5 inches.

12

OSHA Hazard Communication Standard andthe Worker's Right to Know Law

These companion federal and state laws are oftenreferred to as the WORKER’S RIGHT-TO-KNOWlaws. They require employers to inform employees ofany chemical hazards they may be exposed to whileperforming their work. In Connecticut, the DirectorCONN-OSHA oe the Connecticut Department of Laboris responsible for administering and enforcing theseregulations. For more information call (860) 566-4550.

Businesses comply with these regulations when theyimplement the following practices:

Develop a written hazard communicationprogram stating how they comply with the law.Inventory all hazardous materials.Obtain Material Safety Data Sheets (MSDS) onall hazardous materials or products used in theworkplace (MSDS sheets are available uponrequest from pesticide suppliers).Provide employees access to all MSDSs.Attach warning labels for any secondarycontainers that hold hazardous materials.Provide a written policy on how the companywill comply with the law, and allow employeeaccess to the policy.Report information concerning chemicals used,and other information as requested, to the BLS.Provide annual training sessions for allemployees that include:

The location and availability of the writtenhazard communication program and relateddocuments.An explanation of the labeling system andthe material safety data sheets.Any operations in the work area wherehazardous chemicals are present.The physical and health hazards of thechemicals in the work area.Measures employees can take to protectthemselves from these hazards, including thepurpose, proper use, and limitations ofpersonal protection equipment.Methods of detecting the presence or releaseof a hazardous chemical in the work area.Emergency procedures.Document all training including employee

name, job title, date of training, and type oftraining provided.

CONSUMER PROTECTION

It is important to avoid exposing your customers topesticides. It is equally important that the preventativemeasures you take and any public statements you makeregarding consumer protection must be positive andhonest.

Customers in the greenhouse

Is your greenhouse used for retail sales? Do customersand their children browse among your benches? Do youapply pesticides to areas where you also allow customeraccess? If so, then there are some importantconsiderations and precautions you should take.

Although you and your staff routinely takeprecautions to avoid pesticide poisoning, your customerscannot be expected to do this. Customers think aboutpurchases, not pesticide safety. They do not wearprotective clothing and they are unaware of the routinehazards you and other trained professionals recognize.It is your job to protect your customers by warningthem of potential hazards and keeping them out oftreated areas.

13

Do not allow puddles to accumulate on floors incustomer areas. Pesticide residues may run into andconcentrate in such puddles. Without the properprotective boots, contaminated water may soak throughcustomers’ shoes and stockings. Beware of waterdripping on customers from structures and plants hangingoverhead. Customers may also be exposed to pesticideresidues on benches or other structural componentswhere they accumulate from repeated pesticidetreatments.

Children in your greenhouse require extraprecautions. Do not create an “attractive nuisance” byleaving pesticide containers or application equipmentwhere children can see or reach them. In the event ofan accident, you could be held liable. Keep pesticidesand pesticide equipment under lock and key. Make surechildren and other unauthorized people can notenter treated or contaminated areas.

It may be best to establish a totally separate displayand sales area where no pesticides are applied. Thissystem may require frequent inspection to avoid pestinfestations. If pests or pest symptoms are found in thedisplay area, affected plants should be promptly movedto a work area for treatment.

Purchased plants

Most materials labeled for use on ornamentals andother nonfood crops do not list a preharvest interval.Most pesticides list an REI on the product label, but,remember, preharvest and restricted entry intervals arenot the same thing. An REI is the waiting period requiredbefore workers may reenter a treated crop withoutprotective clothing. In contrast, a preharvest intervalestablishes a minimum interval between application andharvest. Once a crop is harvested, it becomes availablefor consumption by the general public. Restricted entryintervals protect workers, while preharvest intervalsprotect consumers. Preharvest intervals are set to ensurethat pesticide residues on food or feed crops do notexceed tolerances set by the EPA when they are madeavailable for public consumption. No residue toleranceshave been set for ornamentals and other nonfood crops.

An equivalent to the preharvest interval does not existfor ornamental crops. Although your customers are notlikely to eat the product that they purchase from you,they may place it on their dinner table, bury their nosein the blossoms, handle and admire the foliage,or place it at the bedside of a sick friend or relative.You must take precautions to prevent any chance ofaccidental poisoning that results from a customer's useof your product. Factors to consider include thepersistence and the toxicity of the materials you applyand the time interval you allow between application andsale. Read labels and MSDS’s or consult CooperativeExtension personnel to compare the toxicity and thepersistence of different materials.

Customer relations

What is your response when customers ask if youuse pesticides? You should consider your responsecarefully. The issue of pesticide residues in ourenvironment is very important. Your customers’questions may be an opportunity to inform them thatyou understand their concerns and have sound policiesin place to minimize pesticide hazards. You may wantto anticipate the question by making a statement on yoursales-label or even producing an informational brochure.Remember to always be honest and courteous in yourresponse.

14

1. Because of the lack of air movement, pesticideconcentrations within a greenhouse can reachharmful levels.

________True ________False

2. A respirator is required whenever a pesticideapplicator or handler is in the greenhouse duringtreatment.

________True ________False

3. Where might greenhouse workers come into con-tact with pesticides?

a. from brushing up against plantsb. by walking through spray mistc. from dripping overhead basketsd. all of these

4. For greenhouse applicators, cotton coveralls pro-vide adequate protection from pesticide expo-sure.

________True ________False

5. List three of the five application practices thatreduce the risk of accidental poisoning over andabove PPE.

a.

b.

c.

6. Application of fumigants in the greenhouse canbe done by a trained and unassisted handler solong as the required protective equipment is worn.

________True ________False

7. For some greenhouse pesticide applications,workers watering plants can remain in an areabeing treated with pesticides.

________True ________False

8. Why is it so important that customers be warnedof potential pesticide hazards?

9. Which situations pose potential pesticide haz-ards to customers?

a. water dripping from overhead hanging plantsb. puddles on greenhouse floorsc. application equipment within sight or reach

of childrend. all of these

10. How can you best avoid customer exposure topesticides?

11. Since ornamental crops are not eaten, pesticideresidues should not be of concern on those crops.

________True ________False

SECTION 2 - REVIEW QUESTIONS

Worker and Consumer Safety Issues

15

Pesticide control treatments are an integral part ofgreenhouse crop production. When used properly, thesechemicals promote the growth of healthy, pest-freeplants. Improper use, however, may lead toenvironmental contamination. Any pesticide that driftsor is applied off-target is a potential pollutant andthreatens the environment. The benefits of pesticideuse are meaningless if our world becomes pollutedthrough misuse and carelessness. It is the responsibilityof the pesticide applicator to keep pesticides on target.This chapter discusses pesticide handling methods ingreenhouses that minimize the threat of pollution. Referto the Core Training Manual for a more generalizeddiscussion of pesticide handling and environmentalprotection.

Federal, state and local authorities are greatlyconcerned about the safe use of pesticides. Currentregulations control product availability, applicationmethods and equipment. These laws are intended toprotect our valuable resources including:

Unique natural habitats,Rare plant and animal species,Surface and groundwater supplies, andOff-target plants and animals, people and sensitive

areas.

POLLUTION FROM GREENHOUSES

The enclosed nature of greenhouses allows a gooddeal of control over the application and dispersal ofpesticides. Newly developed delivery systems combinepesticides with irrigation water and fertilizers to give evengreater regulation of chemical use. However pesticideusers must still pay strict attention to environmentalprotection because the threat that pesticides may escapefrom the greenhouse still remains.

ENVIRONMENTAL PROTECTIONISSUES

SECTION 3

Air movement\Drift

The problem of pesticide drift is relatively easy tomanage in greenhouses. Winds rarely enter to blowpesticide mist off-site. Pesticides may, however, driftfrom the target area into other parts of the greenhouse,or they may escape through vents and doorways.

Factors within the greenhouse that affect drift includetemperature, humidity, ventilation, and heating systems.Inside a warm greenhouse, many pesticides volatilizebecause high temperatures promote the evaporation ofspray droplets. Spray droplets that evaporate quicklyare more likely to drift. On the other hand, the highhumidity inside a greenhouse can suppress evaporationor drying of the spray solution, causing pesticide materialsto persist.

Heating, air conditioning, and ventilation systemsthat move air can also move airborne spray droplets,dust particles, or vapors. Although ventilation systemsmay be left on to achieve better spray coverage, youmay consider turning off some of these systems duringpesticide applications.

Fumigants and other volatile pesticides producevapors that are contained by the walls and other structuralelements of the greenhouse, just as air is contained insidea balloon. The applied material is under pressure within

16

the greenhouse and will escape from any openings inthe structure. Make sure that all doors, windows andvents are securely closed before fumigating or applyingvolatile pesticides. Escaped vapors will reduce controland pose a threat to nontarget plants, workers, andunprotected persons. Once outside the greenhouse,pesticide vapors may cause damage leading to complaintsor even legal action against the applicator.

When applying herbicides to areas outside thegreenhouse, remember that these chemicals are oftenvolatile and nonselective. Herbicide vapors can move tonontarget sites and damage valuable plants. Follow labeldirections restricting the temperature range of properpesticide application. Never apply pesticides whentemperatures are above 85°F or when winds are blowingmore than 5 mph.

Irrigation runoff/groundwater protection

Irrigation water from the greenhouse may containfertilizer, pesticides and other agricultural chemicals thatwill contaminate groundwater. Properties of the pesticide,the soil and the climate all influence whether or not aparticular material actually reaches groundwater. Theseproperties are discussed in your Core Manual.

A pesticide can be both highly soluble and highlyvolatile at the same time. Whether it leaches into thegroundwater or volatilizes into the atmosphere isdetermined by method of application, the ambienttemperature during and after application, and moistureconditions.

Conditions which favor groundwater penetration bypesticides are sandy soils, soils low in organic matter, anacidic pH, and a high water table. Low temperatures,

high rainfall, or applications of largevolumes of irrigation water also favorpenetration. Highly soluble or morepersistent pesticides are more likely

to enter the groundwater than less soluble or lesspersistent pesticides. On the other hand, pesticides thatare broken down by sunlight or microbial action in thesoil or those that volatilize from soil or plant surfacesrarely enter groundwater. Always check the pesticidelabel for specific warnings or instructions regardinggroundwater protection. Information about the propertiesof specific pesticides which may influence groundwatercontamination can be obtained from your Core Manualsupplemental booklets.

A national EPA survey of drinking water wells hasshown that nitrates from fertilizers is a common pollutantof groundwater.

Containing and recycling runoff

It is important to ensure that runoff from thegreenhouse irrigation and pest control operations doesnot enter surface water, groundwater or wetlands.Wherever possible, runoff water should be containedwith impermeable floors to prevent contaminants fromseeping into the underlying soil. Subirrigation systems,holding tanks and artificial wetlands provide additionalrunoff water management.

Subirrigation systems contain all irrigation runoff byrecycling it within the greenhouse. No water escapesthe greenhouse and there is no potential for groundwatercontamination. Subirrigation systems include ebb-and-flood, capillary mat, trough, and nutrient film systems.Your Cooperative Extension office can provide specificinformation about each of these irrigation systems.

Holding tanks and artificial wetlands can be used toretain irrigation runoff. These systems can slow or haltthe movement of runoff water into the environment,allowing time for some agricultural chemicals to breakdown. Artificial wetlands are usually contained by aplastic liner filled with organic soil, flooded with water,and planted with flood-tolerant plants. As chemicals from

17

How much of a pesticide actually leaches isinfluenced by how and when it is used. Even chemicalswith a high potential for leaching will present a reducedhazard when their application is carefully planned.Application factors that influence pesticide leachinginclude:

Timing: withhold or limit applications during wetperiods of the year, such as early spring and latefall, or when heavy precipitation is expected.Groundwater movement is more likely to occur insaturated soils.

Avoid cold soils: cold soils slow down the breakupof pesticides.

Avoid soil-applied pesticides when possible:preemergence pesticides have the greatest risk ofleaching. Although in some cases, the effectivenessof this type of treatment reduces the need for post-emergence applications, which decreases overallpesticide use.

Select foliar application methods: foliar-appliedpesticides may be bound to plant matter anddecompose in soil faster than soil appliedchemicals.

Use IPM practices: monitor pest populations anduse proper alternate control methods when possible.Apply chemicals only when the economic thresholdis reached and pests cannot be controlled by othermeans. Applications made by the calendar canresult in increased environmental and health risks,while providing limited benefit to the crop.

STORAGE AND DISPOSAL

Pesticides should be stored in an area that isstructurally separated from home, office and generalwork areas and from water supplies. A separate buildingor shed is the best arrangement. See your Core Manualfor specific storage regulations.

All doors and entrance ways into pesticide storagefacilities should be clearly marked with warning signs.Storage areas should be locked and secure againstaccidental access by children or other uninformedpersons and against vandalism. Entrances should beplaced where they will not attract children.

irrigation runoff enter an artificial wetland they are brokendown by constant exposure to moisture and air,biodegradation, and uptake by plants. Because somechemicals are not broken down by ultraviolet light,microbes or other natural forces, they may accumulatein holding tanks or in artificial wetlands, creating a hazardfor workers or the public. These systems should befenced.

Environmental risk

The risk of contaminating water resources is an issueof public concern. Once groundwater is contaminated,it is very expensive to clean up, if decontamination iseven possible. Because pesticides are applied ingreenhouses, growers must take steps to safeguardgroundwater supplies.

The potential for pesticides to leach through soil isinfluenced by their chemical nature. Chemical familyand formulation affect several features of pesticidesincluding:

Solubility: pesticides that are easily dissolved inwater are more likely to be carried along bygroundwater movement.

Environmental persistence: soil microorganisms,sunlight, and reactions with soil chemicals breakdown pesticides after application. The longer ittakes a chemical to degrade, the longer it presentsa risk.......

Adsorption properties: pesticides can becomebound to soil particles making them unavailable toleaching. How much of the chemical is bound andhow tightly it is attached depends on the pesticide’schemical reactivity and the type of soil particlespresent.

18

Leakage from damaged pesticide containers in thestorage area could enter and pollute the environment.Storage facilities must be situated on impermeablecontainment pads surrounded by raised berms. Both thefloor and the berm should be sealed to create acontinuous, water tight surface. All leaking or damagedpesticide containers should be placed inside an intactplastic drum or barrel. Always place a copy of theappropriate pesticide labels on the outside of the drum.

Impermeable floors and berms are especiallyimportant where pesticides are stored in bulk containers.Fluid storage tanks should have locked inlet and outletcontrols that prevent unauthorized access. If possible,areas where tanks are kept should be secured by fencesor located entirely inside locked facilities. A containmentsystem to collect precipitation surface runoff or spills isrecommended. Containment systems should be able tohandle at least 1½ times the tank’s storage capacity.

Personal protective equipment such as gloves,aprons and respirators, should be kept near, but not inside,the pesticide storage area. Workers must be able to reachprotective equipment before entering the storage area.Select protective equipment that is appropriate to thetypes of pesticides being stored and the hazards theymay present during routine procedures and possibleemergencies.

A first aid kit equipped for initial response topesticide poisoning should be available to, but not insideof, the storage area. A water supply of sufficient quantityfor emergency wash or eyewash and for routine wash-up should be located conveniently to the storage area.At least 3 gallons of water is recommended for eachhandler using the site.

Inside the pesticide storage facility, pesticides shouldbe separated by type and hazard potential. Herbicides,fungicides and insecticides should each be assignedseparate areas within the facility. Pesticides which areflammable should be separated from nonflammablepesticides. Pesticides which may present a special hazard,such as the release of toxic fumes during a fire, shouldbe assigned to a separate, designated area within thestorage facility. A map should be made of the inside ofthe storage facility showing the main features as well as

the location of each type of pesticide. Copies of thismap should be posted both inside and outside of thestorage facility in areas readily available to emergencypersonnel.

Spill containment materials and fire extinguishers,appropriate for the types of pesticides being stored,should be easily accessed from the pesticide storage area.The local fire department should be notified annually ofthe types and quantities of pesticides being stored. Abasic fire response plan should be prepared, submittedto the fire department, and reviewed regularly.

ENVIRONMENTAL REGULATIONS

State groundwater protection managementplan

Under an EPA mandate, states must developgroundwater protection plans that demonstratereasonable efforts to prevent the contamination of waterresources. By adopting a plan, your state will retain theright to regulate highly leachable pesticides at the statelevel. Without a plan, the EPA would cancel use of suchpesticides within the state. Because some products are relied on for producingcertain crops, it is in the best interest of all applicators toknow and abide by the state plan. For a copy, contactJudith Singer, Department of Environmental Protection,79 Elm Street, Hartford, CT 06106, (860) 424-3369.

19

1. The enclosed nature of greenhouses prevents anyescape of pesticides into the environment.

________True ________False

2. List 5 factors that affect drift of pesticide sprayswithin a greenhouse.

a.

b.

c.

d.

e.

3. High temperatures (over 85°F) can volatilizeherbicides used outside of the greenhouse caus-ing damage to plants near vents or doors insidethe greenhouse.

________True ________False

4. Which are conditions that favor groundwater pen-etration by pesticides?

a. sandy soilsb. application of large volumes of irrigation waterc. Use of highly soluble and persistent pesticidesd. all of these

5. What is a subirrigation system and how does ithelp prevent groundwater contamination?

6. What kind of floor should a pesticide storagehave?

a. dirtb. woodenc. sealed concreted. any of these

7. Personal protective equipment should be keptinside the pesticide storage area.

________True ________False

8. At a minimum, how much water should be avail-able for each pesticide handler using a storage/mixing site.

a. 5 gallonsb. 3 gallonsc. 1 gallon

9. The local fire department should be notified an-nually about the types and quantities of pesti-cides stored at a greenhouse operation.

________True ________False

SECTION 3 - REVIEW QUESTIONS

Worker and Consumer Safety Issues

20

The goal of greenhouse operators is to producehealthy, vigorously growing plants free from all pestproblems. Growers have often met this goal by makingrepeated pesticide applications whether a problem existedor not. However, today’s economic and environmentalpressures place increasing demands on growers to makeprecise management decisions. The current challengefacing growers is to reduce pesticide use and still maintainsatisfactory pest management. Integrated pestmanagement (IPM) is the method growers are turningto for answers. IPM is a pest control strategy thatcombines cultural, biological and chemical techniquesto manage pests in an environmentally responsiblemanner. Growers who practice IPM achieve the sameor better pest control as those who use chemicalpesticides alone.

INTEGRATED PEST MANAGEMENT

Greenhouse operators who use IPM care about thequality of their crop and their environment. IPMtechniques help growers determine when and where pestcontrol is justified. Pesticides are used efficiently bycarefully timing applications and long-term pest controlis maintained with as little effect on the surroundingenvironment as possible. Growers and managers responsible for producingsuch greenhouse crops as potted plants, bedding plants,cut flowers, hanging baskets, or vegetables, can use theIPM techniques described in this chapter to:

Protect crop quality,

Safeguard public health,

Protect the environment,

Reduce pest management costs, and

Use pesticides wisely.

SECTION 4

IPM TECHNIQUES

The IPM techniques most useful to greenhouseproduction systems are scouting, pest identification,timing treatments, and record keeping. You can learnIPM techniques from the Cooperative Extension or fromprivate IPM consultants.

Monitoring and scouting

Scouting, also known as monitoring, is the basiccornerstone of IPM. Scouting is a visual inspection ofthe crop and pest traps to determine the health of thecrop, its growth stage, what and how many pests arepresent, and what trends pest populations are following.Routine and careful scouting will detect pest populationswhen they first appear; that is, when they are easiest tocontrol and before damage occurs. A grower who knowswhether or not pests are present in a crop can replace aroutine, preventative spray schedule with fewer, butbetter timed and more effective treatments. When a pest is found on only a few plants or in asmall area, localized control tactics are used. Spottreatments not only decrease the chance of misapplicationor over-application, but use less material than blanketsprays and, thus, help to preserve beneficial organisms.

GREENHOUSE IPM

21

Scouting guidelines

It is important to scout routinely, at least once everyweek through a crop's entire production cycle. Scoutingtwice a week is even better. Scout on a specific day andtime and keep the same schedule throughout the season.This allows growers to track the development ofproblems and to catch new pests when they first appear. The common pests found in greenhouse crops donot distribute themselves evenly through a crop.Therefore, the entire greenhouse must be scouted in aconsistent pattern. Inspect plants grown on the ground,benches, and hanging from the greenhouse frame. Thesize of the greenhouse, the number and size of plants,and the size and location of the benches will influencethe pattern and time needed to scout. Follow the samepattern each week. Start your scouting pattern in one corner and end inthe opposite corner. Walk through every aisle. Selectplants randomly, but choose plants from every benchand from the ends and the middle of each bench. Themore plants inspected, the better, especially if the benchesare long. Always look underneath the benches for weeds. Inspect each plant the same way. Start at the soilsurface and work your way up the plant. Most of theinsects will be on the underside of the leaves. Forexample, all immature greenhouse and silverleafwhiteflies are on the underside of the leaves. Start byturning over the older, lower leaves. Tipping the potsideways may help. Then examine younger leaves furtherup the stalk. Finish with the flush growth. When youfind a plant with a pest, flag it. This way you can relocatethe pot and watch pest development. The flagged plantis your indicator plant. After you treat, go back to yourindicator plant, turn the leaf over and see if you controlledthe pest. As you scout, record on a field data sheet theidentification, location, growth stage, and severity of allpests present. Include how many individuals are countedand a description of the symptoms. You may also wish

Standard zig-zag scouting pattern down aisles andbetween benches

to record physical data like day/night temperature, relativehumidity and light levels. Preparing data forms in advancewill save time and make analysis more consistent. Ifyou find a plant or area that is more heavily infestedthan the rest of the greenhouse, take special note of thelocation. Take notes on where and what kind of weedsyou find. Take notes on anything that you observe thatis not normal. Count and record the total number ofplants inspected. These notes can become valuablerecords of how pest problems develop and what controlmeasures really work.

Insect monitoring cards

The benefits of insect monitoring cards include:

Early pest detection

Improved pest management decisions

Improved timing of treatment applications

Documentation of pests and their locations

Measurement of pest population trends

Insect monitoring cards, also known as sticky cardsor sticky traps, are used to detect the presence of insectpests and to estimate the relative size of pest populations.Sticky traps are made of a stiff paper card, usually coloredbright yellow, covered with a nondrying, sticky substancewhich traps insects. Regular inspection and replacementof these cards provides up-to-date information on pestpopulations. If trap counts increase within an isolatedarea, that location may be spot treated. If the populationis widespread, the entire greenhouse may need treatment.This approach maximizes the effectiveness of aninsecticide and minimizes its use. After the treatment,fresh sticky traps are a convenient tool to gauge thesuccess of the application.

22

Insects trapped on sticky cards provide excellentsamples for positive identification of pest species. Bluesticky traps are specifically designed to attract thrips.Yellow sticky cards attract a wider range of insectsincluding the following adult pests:

Greenhouse whiteflies,Silverleaf whiteflies,Western flower thrips,Fungus gnats,Shore flies,Leafminers,Winged aphids,Leafhoppers,Other flying insects.

When placed horizontally at soil level monitoringcards work very well for early detection of newlyemerged adult thrips, fungus gnats and leafminers.

How to use monitoring cards

The key to a successful monitoring program is theplacement of the cards. Always place the cardsimmediately above the plant canopy. This is where mostpest flight occurs. Depending on personal preferenceand growing conditions, there are a number of ways toattach and position the cards.

Attach the card vertically to a wire or wooden stakeby stapling it or clipping it on with a clothespin. An

Insects on sticky traps

23

especially useful method involves gluing two clothespinsback-to-back. One of the clothespins attaches to a stake,and the other is clipped to the card. This allows you tomove the card upward as the plant grows in height. Toavoid using stakes, punch a hole in the card and tie astring or wire to the card and suspend the card from thegreenhouse frame. Hang the card vertically at and justabove the top of the canopy.

Space monitoring cards equally throughout the entirearea in a grid pattern. For best results place one card per1000 sq. ft. For plants located on the floor or on benches,place the card just at the top of and over the plant canopy.As the plants grow, move the cards upward.

Keep insect monitoring cards in the greenhouse allthe time. When installing the cards, number and dateeach card. It is important to record the pest levels onthe field data sheet each week. Change the cards weekly.Place the cards in the same locations each week. Drawa map of the greenhouse and mark the location of eachsticky card on the map.

Sticky cards are excellent for detecting pest migrationinto the greenhouse. Place cards near all entry waysincluding doors, sidewall and roof vents. Group yourpest susceptible varieties together and place additionalcards in these areas of the greenhouse. If a low pestpopulation level is detected, immediately treat the area.

Place extra monitoring cards in areas where pestshave previously been a problem. If a low pest infestationis detected, treat the area immediately.

Pest identification

The first step in pest management is accurate pestidentification. In order to implement IPM techniques itis essential to know the major pests that are likely toappear, where to look for them, and how to identifythem. It is also important to understand the biology of apest and its interaction with other organisms and itsenvironment.

Early identification and accurate diagnosis arefundamental to a successful IPM program. Misdiagnosiscan result in improper control. Many chemicals areeffective only at certain stages of the pest’s life cycle.For example, wet spraying for whiteflies works best

when the majority of the whiteflies are in the early instarphase (first and second instars).

It is very useful to collectpest samples from yourgreenhouse and preserve themin vials filled with rubbingalcohol. Label them with thepest identification, the date andthe location. They will becomean important tool foridentification and training newscouts. For help in identifyingyour pests contact theCooperative Extension Service; or Kenneth Welch, CTAgricultural Experiment Station, 123 Huntigton Street,New Haven, CT 06511, (203) 789-7239; or RichardCowles, CT Agricultural Experiment Station, ValleyLaboratory, 153 Cook Hill Road, Windsor, CT 06095,(860) 688-3647.

Timing

Many pesticides are only effective against certainpests, and often only against certain life stages of thatpest. For example, insecticides are most effective againstscales and mealybugs during their crawling stage, beforethey have produced their protective waxy covering.Pesticides applied against the wrong life stage of a pestare not likely to be very effective. This is one reasonwhy it is important to know the correct identity of apest as well as its life cycle and biology. In general,control treatments are most affective when they targetthe life stage of the pest that was scouted as being mostnumerous. For example, if more larvae are found thanadults, use a larvicide; if adults predominate, use anadulticide. Repeated applications may be necessary togain control of pests with overlapping life stages.

CONTROL METHODS

When control of a pest population is necessary, thereare many control activities available. The specific methodselected should be based on the type of pest causing theproblem and the severity of the loss if the desired controlis not achieved. Control methods fall into four basicgroups:

Cultural practices: in general, any activity thatpromotes plant health and vigorMechanical methods: crop management activitiesoften performed by hand labor in greenhouse crops

24

Biological controls: utilizing predators, parasitesand pathogens to manage pest populations.Chemical controls: when cultural and mechanicalmethods cannot provide the desired control

CULTURAL PRACTICES

Cultural controls are horticultural practices thatdisrupt or reduce pest populations. Effective culturaltechniques include sanitation, resistant crop varieties,fallow periods, and modification of watering practices.Refer to Section 8 for further discussion of culturalpractices that relate to plant health.

Sanitation

Sanitation provides the first line of defense againstpest infestations by preventing the introduction of pestsinto uninfested areas. General practices include washinghands between crop production activities, wearing cleanclothing, and avoiding placing plants, hose ends and othertools on the floor or any other contaminated surface.These practices will help to prevent the spread of pests.

Other sanitation practices include the inspection ofincoming plant material before it is allowed into thegrowing area and the isolation of infested plants in aquarantine area. Bench surfaces, tools, plastic pots, andother crop production equipment should be disinfectedbetween uses. Although heat is an effective sterilant,materials such as plastics may not withstand hightemperature treatment. Chemical disinfectants labeledfor this purpose are more commonly used.

Procedures should be designed for handling growingmixes, tools, and equipment to avoid contamination ofthe growing medium. Pasteurization of the growingmedium is required if soil, sand, or other materialsexposed to pests are used.

Weeds are a constant source of pest reinfestation.Pests such as whiteflies, aphids, thrips and plantpathogens live on weeds around the exterior of thegreenhouse. Remove weeds for at least 10 feet aroundthe perimeter of the greenhouse. Black plastic mulchcovered with coarse gravel can be used to maintain thisweed-free zone. It is especially important to keep weedsaway from entrances and inlet vents.

Soil and plant debris should be removed from thegreenhouse daily and placed on the compost pile or in acovered container away from the greenhouse. Locatecompost piles at least 500 feet from the greenhouse.

Crop resistance

Crop varieties may have partial or completeresistance to a pest. If the number of pests on a varietyis reduced but not eliminated, resistance is partial. Whereno pests are found on the plants, the variety is said tohave complete resistance.

Susceptible varieties should be placed together inthe greenhouse and closely monitored. This enhancesearly detection of pest problems.

Sometimes better chemical pest control is achievedusing resistant varieties. In addition, biological controlorganisms may be more effective when used withresistant crop varieties. In situations where plantresistance is not complete, partial resistance can at leastaid in reducing pesticide use.

Fallow periods

Insects and mites can be a constant problem ingreenhouses because there is often a continuous supplyof plant material for food and reproduction. If all plantmaterial is removed for a sufficient period of time, thesepests may die of starvation. This is particularly true incool, temperate areas where vents and doors can beclosed for much of the year to restrict pest movementinto and out of the greenhouse. To ensure effectiveness,the greenhouse temperature should be sufficiently warmduring the fallow period to prevent pests from goinginto diapause (hibernation). All plant material of anysort, including weeds, must be removed. Fumigation ofan empty greenhouse may increase the effectiveness ofthis tactic. Pests may also be eliminated by allowing agreenhouse to freeze overnight during winter. Obviouslythe economics of crop production may preclude fallowperiods in a greenhouse, but the idea should be kept inmind when considering pest control options.

Watering practices

Overwatering can lead to plant disease problems,poor soil aeration, wet soil beneath benches, standingwater and more. Algae, fungi and other organic materialwill grow in these moist areas, and lead to problemswith fungus gnats and shore flies.

Conversely, plants that are under water stress areoften more susceptible to insect and mite problems.Spider mites, in particular, favor dry environments.Careful attention to watering practices can reduce pestproblems.

Plants are 80 to 90 percent water. The water in planttissues holds the leaves and stems erect and is essential

25

Pruning and roguing

It is sometimes more cost effective to discard infestedplant material than to attempt chemical control. This istrue for many plant diseases, such as tomato spottedwilt virus which is vectored by western flower thrips.Pruning infested plant parts can also be an effectiveway to manage some pests on some crops. For example,removal of the lower leaves of poinsettias, after a healthyupper canopy develops, often reduces whitefly numbers.

BIOLOGICAL CONTROLS

Problems associated with pesticides have createdthe need for alternative pest control strategies that areeconomical, and effective. Biological control techniquesare now available that may fill this need. Biologicalcontrol uses living organisms (parasites, predators orpathogens) that are natural enemies of pests to regulatepest populations. The goal of biological control is tokeep pest populations at a level too low to damage thecrop, but just high enough to sustain the population ofthe natural enemies.

Predators and parasites

Predators are organisms that capture and devourtheir prey. Probably the most commonly knowngreenhouse predator is the ladybird beetle. A singleladybird (or ladybug) can eat 50 aphids per day. Otherimportant insect predators include:

Lacewings which feed on aphids, scales,mealybugs, thrips, mites, and insect eggs;The larvae of syrphid flies (also called ‘flowerflies’) which consume aphids and small ants;Pedatory mites which feed on the all-too-commontwo-spotted spider mite; andPredatory nematodes such as Steinernemacarpocapsae, sold as BioSafe or Vector, that feedon certain soil inhabiting pests like fungus gnatlarvae.

for cell division and growth. Movement of water fromthe roots to the leaves circulates nutrients, removes wasteproducts and helps cool the plant. Excess water is justas hazardous to plant health as lack of water.

MECHANICAL METHODS

Mechanical techniques use physical means to controlpest numbers. Screens that exclude or confine pests,vacuuming, pruning and roguing are all examples ofmechanical pest controls.

Screens

Entry-ways, air blasts and screens can be used tokeep flying insects out of the greenhouse although screensalso hinder air movement. Screens may also be used toseparate the greenhouse into ranges to prevent pestsfrom spreading throughout an entire production area.Pests physically confined to one part of the greenhouseare more easily controlled.

Because pests can be transported on clothing,workers should not be allowed to enter an uninfestedarea once they have visited an infested area, unless theyare first disinfested.

Weed control

Weed control in the greenhouse cannot be over-stressed! Weeds harbor insects, mites and plant diseases.No weeds should be tolerated in the greenhouse. Removeweeds regularly.

Remove unhealthy looking plants. Rogue outdiseased or heavily infested plants. Check plants thathave been in the greenhouse for over three months orplants that have become “pets”. These plants can harborpest infestations.

26

Parasitic insects which are useful as pest controlslay their eggs on or in the body of a pest species. Whenthe eggs hatch, the immature or larval stages of theparasite develop by feeding on and killing the pest insect.

Parasitic insect species are highly specialized andusually will attack only one species of pest. Parasitesuseful in greenhouses are usually minute species ofwasps that attack aphids, scales, whiteflies, leafminers,and other pest insects. See Appendix B for moreinformation on commercially available parasitic species.

Pathogens

Pathogens are disease causing organisms includingbacteria, fungi, viruses and nematodes. They play animportant role in regulating pest populations. Severalimportant pathogens are now marketed as pest controlagents. For example the bacterium Bacillusthuringiensis, or "Bt", is marketed as an Gnatrol andprovides control of a variety of leaf chewing caterpillars;and the fungus Verticillium lecanii, sold as Vetalec orMycotel, helps control aphids and whiteflies in humidgreenhouses.

CHEMICAL CONTROLS

Pesticides exhibit great variation in their effectivenessagainst individual pests. Some insecticides will controlthe immature forms of a pest but will not control theadult. Some insecticides are effective against mites, butmost miticides (acaricides) are ineffective against insects.It is important to use an appropriate chemical againsteach pest to avoid wasted time, money, and pesticide.Pesticide labels contain information and specificinstructions about which pests a product will control.

The shelf life of a pesticide can also affect itsefficacy. Consult the pesticide label or the manufacturerif you have a question regarding the shelf life of apesticide.

The misuse or overuse of pesticides can lead toproblems with resistant pests. Pesticide resistance meansthe loss of previously effective chemicals and more costlyalternatives. Some tactics for managing resistance arepresented later (see “Managing resistance to pesticides”).

Delivery

The method of pesticide delivery greatly affectstreatment efficacy. In general, chemical control is mostsuccessful using application equipment that creates smallpesticide droplets with uniform particle distribution, whileproviding good canopy penetration. The movement ofsystemic pesticides can compensate for incompletecoverage. Pesticides with systemic properties are ableto move across leaves from the upper to the lower leafsurface. Systemic pesticides are taken up by a plant'svascular system and transported throughout its variousparts.

Amount

The amount of pesticide used can affect its efficacy.The pesticide label is a legal document that is your guidefor determining how much pesticide to use. For systemicinsecticides applied to the soil, be sure irrigation watercontacts the granules to release the insecticide into thegrowing media. The effectiveness of systemic insecticidescan vary with the age of a plant and the amount ofwatering.

Managing resistance to pesticides

Insecticide resistance is a major concern for almostall the important greenhouse arthropod pests. Acombination of factors has led to current resistanceproblems. These include pest biology, the intensity ofpast and present chemical use, aspects of the greenhouseenvironment, and commercial production practices. Thefollowing discussion suggests some useful ideas for anychemical control program.

Minimize insecticide use. If pest control reliesexclusively on synthetic insecticides, then resistance islikely to occur. Therefore, the use of nonchemical controltactics (sanitation, weed elimination, soil sterilization,screening vents, biological control) should be maximized,and chemicals should be used sparingly.

Avoid persistent applications. Ideally, an effectiveinsecticide should be applied at a concentration highenough (but not exceeding label limits) to kill allindividuals in a population; then it should quickly

27

disappear. Pesticides which instead degrade slowly overtime eventually are present at low concentrations thatwill kill only the most susceptible individuals. When onlythe weak individuals are removed from a population,only resistant individuals are left to reproduce creatingan even more resistant population.

Aerosol formulations apply a short burst of highlyconcentrated insecticide and leave little residue. Thisapplication may select for resistance more slowly than afull coverage spray of the same insecticide, as long asresistance to the insecticide has not already developed.

Avoid tank mixes of more than one pesticide. Amixture of two insecticides may provide much greatershort-term control than either insecticide used alone, butthere is a danger in the long-term use of insecticidemixtures. The assumption behind the use of tank mixesis that there is little chance of resistance mechanisms toboth pesticides occurring in any one individual. If thisassumption is false, then continued use of the tank mixwill select for these doubly resistant pests. Chemicalcontrol would then become much more difficult, becausethe pests would be resistant to multiple classes ofinsecticides.

Use long-term insecticide rotations. Use eacheffective insecticide for at least the duration of one pestgeneration before rotating to a different insecticide. Iftwo insecticides are used within the same pest generation,the selection effect will be essentially the same as usinga tank mix. This is because the same individuals wouldcome into contact with both insecticides, although atslightly different times. To minimize the problems ofoverlapping generations and persistent insecticideresidues, it might be wise to use the same insecticide fortwo or even three generations prior to rotating. Thepesticides used in a rotation scheme should have differentmodes of action against the pest (i.e., they should be ofdifferent chemical classes), and resistance to thechemicals should be at a low level. For example,organophosphate and carbamate insecticides have similarmodes of action and they should not be alternated in aninsecticide rotation scheme.

Use pesticides with nonspecific modes of action.Insecticidal soaps and horticultural oils both have broadmodes of action, and it is therefore unlikely thatresistance will occur with either of these.

Integrate chemical and biological control. Insecticidesapplied to control insect pests can also harm or eliminatepopulations of beneficial insects which have beenpurposefully introduced into a greenhouse. Research hasidentified many insecticides that are compatible with theuse of beneficial insects. The effective use of beneficial

insects can add an additional mortality factor that doesnot select for resistance and may conserve theeffectiveness of insecticides.

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1. List the 4 IPM techniques most useful to green-house production systems.

a.

b.

c.

d.

2. What is the basic cornerstone of IPM?

a. pesticide application timingb. scoutingc. mechanical controld. records

3. Since most greenhouse insect pests are found onthe top sides of the leaves, plant inspectionshould start from the top of the plant and workdown towards the soil.

________True ________False

4. Using Figure 1 below, draw a line to show aneffective scouting pattern.

5. Blue colored sticky cards are specifically de-signed to attract white flies.

________True ________False

6. Which are benefits of insect monitoring cards?

a. early pest detectionb. estimate size of pest populationsc. gauge success of pest control treatmentsd. all of these

7. Sticky traps should be placed just above the plantcanopy.

________True ________False

8. For best results, how many sticky cards are neededto monitor 10,000 sq. ft. of plants?

a. 5b. 8c. 10

9. How often should sticky cards be changed?

a. dailyb. weeklyc. monthly

10. You must properly identify the pest and under-stand its life cycle and biology in order to knowthe proper timing of control measures.

________True ________False

11. ______________ provides the first line of de-fense against pest infestations by preventing theintroduction of pests into uninfested areas.

12. Why should weeds around the exterior of green-houses be removed?

SECTION 4 - REVIEW QUESTIONS

Greenhouse IPM

FIGURE 1

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13. During fallow periods, greenhouses should notbe heated.

________True ________False

14. Which pest problem is an indicator of waterstress or dry environments?

a. spider mitesb. fungus gnatsc. algaed. shore flies

15. List four examples of mechanical pest controls.

a.

b.

c.

d.

16. Biological controls are an effective way to to-tally eradicate a pest.

________True ________False

17. Most insecticides are effective against mites.

________True ________False

18. Which situations are likely to lead to pest re-sistance to pesticides?

a. exclusive reliance on synthetic pesticidesb. use of persistent pesticidesc. repeated use of tank mixesd. all of these

19. To reduce pest resistance development, howlong should the same insecticide be used?

a. one time onlyb. for the duration of at least one pest generationc. less than the duration of one pest generation

20. Why is it unlikely that insects will ever developresistance to products like insecticidal soaps andhorticultural oils?

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PESTICIDES FOR GREENHOUSE PRODUCTION

SECTION 5

The label is the first and best source of informationabout using a pesticide. READ IT. Do not rely on coloror design of the packaging when selecting a product.Many manufacturers offer a line of different chemicalsthat all are packaged the same. They may also havesimilar sounding names but they are actually very differentcompounds.

Before you buy a pesticide, READ THE LABEL.

Before you store a pesticide, READ THE LABEL.

Before you mix a pesticide, READ THE LABEL.

Before you apply a pesticide,READ THE LABEL.

Before you dispose of pesticides or containers,

READ THE LABEL.Federal regulations make it illegal to remove or

destroy pesticide labels, or to use pesticides in anymanner not listed on the label. THE LABEL IS THELAW. This includes the information on the pesticidecontainer and any written material supplied by themanufacturer. For a discussion of the parts of the labeland the type of information provided, review the CoreManual.

Pesticide activity

Pesticide products used in greenhouse productioninclude the following:

Insecticides: effective against insects and relatedarthropod pestsFungicides: for reducing the spread of plant diseasescaused by fungiHerbicides: to control unwanted plant growthSoil fumigants: used to reduce soil pests prior toplanting crops

SELECTING A PESTICIDE

There is a great variety of pesticides available.Chemicals are available to control nearly every type ofgreenhouse pest. There are several important factorsto consider before using any pesticide. The first andmost important step is correct identification of theproblem:

Inspect plants to confirm that the problem is causedby a pestCorrectly identify the pestMake sure the chemical you choose will controlthe pestMake sure the pest is in a susceptible stage ofdevelopmentBefore purchasing a pesticide, consider its properties

in relation to both the pest problem and the treatmentlocation. The best way to learn about a product is toREAD THE LABEL. Select the lowest risk productavailable based on:

Signal wordPotential health hazardsPests controlled/mode of actionEnvironmental hazardsFormulationAdjuvants

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Modes of action

The way a pesticide acts against the living systemsof pest organisms is called its mode of action. Generally,pesticides in the same chemical family have the samemode of action. If the desired control is not obtainedwith one product, understanding chemical families andmodes of action makes it easier to select alternateproducts that will provide control. For example, manygreenhouse insecticides poison the central nervous systemof pests. If bifenthrin (Talstar) fails to provide control,switching to permethrin (Pounce) does not change themode of action. Both are pyrethroids that interfere withtransmission of impulses between nerve cells. Endosulfan(Thiodan) is an organochlorine pesticide that also workson the nervous system but with a different mode of actionand, as a result, it may provide better control in thisexample.

In addition to having similar modes of action,pesticides in the same chemical family share other featuresin common. They are often available in the sameformulations and used in much the same manner. Theirpersistence in the environment is usually comparablebecause the natural processes that degrade them are thesame. Toxicity and risks to users also tend to be similar.There are, however, many exceptions to these similarities.

Pesticide action may occur where the chemicalcontacts the pest (contact pesticides), or within the pestafter the chemical is eaten or absorbed (systemicpesticides). Some chemicals exhibit both types of activity.Systemic pesticides applied to plants are also calledtranslocated pesticides. These chemicals move withinthe plant (or translocate) and control the target pest whenthe plant is attacked by disease or insects.

Where a resistant pest population is likely to develop,different chemical families should be routinely alternated.Don’t simply change brands; similar compounds areproduced by many companies. Read the label to makesure the products contain different active ingredients withdifferent modes of action. Using products with differentmodes of action slows the development of resistance.Separating chemical treatments with mechanical orbiological controls further reduces the development ofresistance.

COMMON GREENHOUSE PESTICIDES

Common formulations

The Core Manual introduces the commonly availablepesticide formulations. Many aspects of pesticide useare influenced by the formulation. The most important

factors to consider when selecting a product include:Health risks associated with using the formulationRequired application method and equipmentRisk of environmental damage by leaching or drift

Mixing pesticide products

Mixtures of two or more pesticides applied at thesame time may provide added benefit for the greenhousegrower. Although tank mixes may lead to resistancedevelopment, by carefully selecting pesticides, bothimmediate and long term control may be achieved.Treatment for more than one pest at a time reduces thetime and labor invested in control, leading to substantialsavings. Approved combinations can be mixed by theapplicator, as needed. READ THE LABEL. Tank mixesprepared by the applicator must be consistent with labelinstructions.

Some formulations and chemicals may beincompatible. This can result in loss of effectivenessagainst the target species, increased damage to nontargetplants, increased hazard to applicators, or the cloggingof equipment. READ THE LABEL. It may list whichformulations are compatible, and the order in which theymust be added.

If combinations are not specifically restricted andcompatibility is not stated on the labels, a jar test can beperformed to determine compatibility of two or moreproducts. Wear all personal protective equipment requiredby the most hazardous product when performing thistest. Place one pint of water (or other carrier) to be usedfor tank mixing in a clean quart jar. The equivalent ofone pound or pint per 25 gallons of finished mix isobtained by using the following amounts. Add productformulations in the order shown below, mixing after eachaddition.

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1- ½ teaspoon of compatibility agents, activa-tors or surfactants

2- ½ tablespoon of wettable powder or dryflowable formulations

3- ½ teaspoon of water soluble concentrates orsolutions

4- ½ teaspoon of emulsifiable concentrates orflowables

5- ½ teaspoon of soluble powder formulations6- ½ teaspoon of any additional adjuvants to

be used, such as spreaders or stickersCap the jar tightly and invert 10 times. Inspect the

mix immediately for uniform mixing. If sludge, clumpsor non-dispersing oils are not formed, wait 30 minutesand check again. Minor separation that remixes easily isacceptable if tank agitation is good. If the formation ofgums, sludge or clumps indicates incompatibility, do notuse this combination of products. Dispose of the testmix according to label directions or, if unusable, followDEP guidelines for hazardous materials.

The jar test only indicates chemical mixingcompatibility; it does not indicate the effect it has onpest control activity. Some mixtures have an increasedrisk of phytotoxicity and they may promote thedevelopment of resistance to several types of pesticidesat once. Compatible combinations should be tested on asmall portion of crop. Wait several days after makingtest applications for injury symptoms to appear beforemaking large scale applications. Application rates,schedules and precautions for using specific productsare given in the New England Greenhouse FloriculturalCrop Pest Management and Growth Regulation Guide.This guide is produced every two years by CooperativeExtension specialists in the New England region. Toobtain the current issue contact The University ofConnecticut, Communications and InformationTechnology, 1376 Storrs Road, Storrs, CT 06269-4035,(860) 486-3336.

ADJUVANTS

Activity of adjuvants

Adjuvants, or additive compounds, aid in the mixing,application or effectiveness of pesticides. One class ofadjuvants, compatibility agents, allow uniform mixingof compounds that would normally separate. Other typesof adjuvants include spreaders, stickers, and synergists.There are nearly as many adjuvants as there arepesticides, and they provide a choice for every need.

Some adjuvants are added during pesticide manufactureand are, thus, part of the formulation. Other adjuvantsare added just before application. To decide when touse an adjuvant, READ THE LABEL. It will state whena particular adjuvant is needed, whether or not one shouldbe added or when one is already present.

Adjuvants assist application or pesticide activitywithout being directly toxic to pests. However, many ofthese chemicals can present hazards to the applicators.The EPA has not required manufacturers to perform thesame type of research and reporting on adjuvants that isrequired for pesticide registration. However, regulationsare continually updated to protect the health of applicatorsand review and registration of adjuvants may be requiredin the future. Meanwhile, it is a good practice to use thesame care in handling adjuvants as is used with pesticides.

Many, but not all, adjuvants function as surfactants,or surface active agents. Surfactants improve theretention and absorption of herbicides. The benefit theyprovide is offset, to a degree, by the increased drift hazardthey cause. Reducing the surface tension of the spraysolution permits it to break up into finer droplets, whichare more likely to drift off target.

Drift control agents are adjuvants that help reducethe risk of drift. Pesticide drift is off-target spray depositand off-target damage. Spray thickeners reduce driftby increasing droplet size and by reducing bounce orrunoff during application. Use of these adjuvants helpsto comply with drift regulations, which is especiallyimportant in areas adjacent to residential areas. Lo-Drift, Nalco-Trol and Drift Proof are examples of driftcontrol agents.

Penetrating agents dissolve the waxy layer thatprotects the surface of leaves. This speeds up absorptionwith foliar treatments. Lower application rates used withthese adjuvants may provide the same control as higherrates made without them; more chemical enters the plantbefore breaking down or washing off. Examples ofpenetrating agents include Arborchem and kerosene.

PROPER HANDLING OF PESTICIDES

Using pesticides involves many responsibilitiesbeyond the immediate needs of pest control. Greenhousegrowers, like all agricultural producers, are expected tohandle hazardous materials in a manner that reduces theexposure risk to other persons and limits contaminationof the environment. Numerous federal and stateregulations exist to help growers handle, store and applypesticides properly.

33

In addition to FIFRA, EPA has further authority overpesticide use under the Superfund Amendment andReauthorization Act (SARA) and the ResourceConservation and Recovery Act (RCRA). These federalregulations cover all materials classified as hazardousand, therefore, apply to pesticides. Pesticide handlingand storage are also regulated by the TransportationSafety Act and the Occupational Safety and Health Act(OSHA).

Moving pesticides

Interstate transport of pesticides is regulated by theFederal Department of Transportation (DOT). Theirguidelines for safe movement are common sense rulesfor any transport of chemicals. All pesticides should bein the original DOT approved containers and correctlylabeled. All containers should be secured againstmovement that could result in breaking or spilling. Nevertransport pesticides in a vehicle that also carries food orfeed products. Never transport pesticides in the cab ofvehicles. Paper or cardboard containers should beprotected from moisture. Never leave an open-bed truckcontaining pesticides unattended. Following theseprocedures is necessary when moving concentratedchemicals and is good practice for diluted mixtures.

Persons transporting chemicals must have properprotective clothing available for the safe handling of thecontainers. The protective gear should be in or on thevehicle for immediate access in case a spill occurs.Protection of the person managing or cleaning up a spillis the primary concern.

SPILL CLEANUP AND REPORTING

What to do when a spill occurs

When a minor spill occurs, make sure the properprotective equipment is available, and wear it. If pesticidehas spilled on anyone, wash it off immediately, beforetaking any other action. Confine the spill with a dike ofsand or soil. Use absorbent materials to soak up thespill. Shovel all contaminated material into a leak- proofcontainer and dispose of it in the same manner as excesspesticides, as described in the Core Manual. Do not hosedown the area; this spreads the chemical. Always workcarefully to avoid making mistakes.

Streams and wetlands must be protected in the eventof an accidental spill of any size. Even diluted chemicalspose a threat to natural habitats when released in largeamounts. Extra precautions must be taken when drawingwater from streams or ponds. Antisiphoning devices mustbe used and be in good working order. Tank mixes shouldbe prepared at least ¼ mile from water resources. If thisis not possible, make sure the ground at the mixing sitedoes not slope toward the water, or construct an earthendike to prevent pesticides from flowing into bodies ofwater or drains.

Major spills of concentrates or large quantities ofspray solution are difficult to handle without assistance.Provide any first aid that is needed and confine the spill,then notify the proper authorities. Contact the local firedepartment using the 911 system, if available. Otherphone numbers for fire departments, state and localauthorities should be carried in the vehicles and by theapplicators.

Regardless of the size of the spill, keep people awayfrom the chemicals. Rope off the area and flag it towarn others. Do not leave the site unless responsiblehelp, such as emergency or enforcement personnel, isthere to warn others.

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Significant pesticide spills must be reported to:Oil & Chemical Spill Response

Department of Environmental Protection79 Elm Street

Hartford, CT 06106(860) 424-3338

Applicators, or their employers, are responsiblefor telephoning a spray incident report as soonas practical after emergency health care andefforts to contain the spill have started. The stateagencies decide if it is necessary to callCHEMTREC (Chemical TransportationEmergency Center), a public service of theManufacturing Chemicals Association located inWashington, D. C. CHEMTREC providesimmediate advice for those at the scene of anemergency. This service is available 24 hours aday (1-800-424-9300) for emergencies only.

35

1. Where a resistant pest population is likely to de-velop, pesticides with differing modes of actionshould be alternated.

________True ________False

2. Cost of the product is the most important factorto consider when selecting a pesticide.

________True ________False

3. Which type of adjuvant dissolves the waxy layerthat protects the leaf surface and improves ab-sorption of pesticides.

a. stickersb. spreadersc. penetrating agentsd. synergists

4. Tank mixing two pesticides together may pro-mote the development of pest resistance to bothpesticides at once.

________True ________False

5. If a minor spill occurs you need not wear anyprotective clothing when cleaning it up.

________True ________False

SECTION 5 - REVIEW QUESTIONS

Pesticides For Greenhouse Production

36

EQUIPMENT AND CALIBRATION

SECTION 6

The scale of greenhouse production varies greatlyfrom one operation to another. It may range from a fewbenches of mixed seedlings to an entire house dedicatedto a single crop. Appropriate pesticide applicationequipment should be used at each individual site. Usingthe proper equipment will make pesticide applicationseasy and efficient.Selecting application equipment is as important aschoosing the proper pesticide. Usually, a single sprayerwill not meet all the needs of a greenhouse grower. Thechoice of equipment is influenced by these factors:

Type of pesticides and/or fertilizersPesticide formulationsCapacity of equipment compared to size of crop

areasOperator safety featuresEase of operation, calibration and maintenanceCrops grown

GREENHOUSE SPRAYERS

Manual sprayers

Where several greenhouse crops are grown near eachother, manual sprayers are useful because of their limitedsize and spray range. Individual plants or weed patchescan be easily spot-treated while not affecting neighboringrows. Several types of sprayers are available that deliver0.1 to two gallons per minute (gpm) at pressures up to100 pounds per square inch (psi). Their small capacityis adequate only when a few plants or rows requiretreatment. These sprayers are relatively inexpensive,simple to operate, easy to handle and easy to clean andstore.

TRIGGER PUMP SPRAYERS areused for many types of liquid applications.Squeezing the trigger forces spray mixtureout of the nozzle as a stream. Droplet sizecan be controlled on some models withadjustable nozzles. Capacity of the plasticspray bottles is very limited, usually lessthan one gallon. These are generally used

for spot spraying of weeds with ready-to-use herbicides.Areas accessible to garden hoses or water wagons

can be treated with HOSE-END PROPORTIONERS.

These simple mixers use the flow of water to drawconcentrated pesticide from the reservoir. Chemicals aremixed with the water stream as it leaves the hose. Anyformulation that is diluted with water can be applied withthis equipment, but wettable powders and emulsifiableconcentrates require frequent shaking. Severalprecautions must be taken with hose-end proportionersfor safe use and proper application. Handlingconcentrated pesticides requires adequate protection withpersonal protective equipment. Extra care is needed toprevent spills, splashes and misapplications. Theproportioner must be checked for correct functioningand be calibrated before each use. An antisiphoningdevice must be installed between the proportioner andthe water source to prevent backflow and contaminationof water supplies.

Manually powered KNAPSACK SPRAYERSconsist of a liquid supply tank, pump, holding chamber,hose and wand assembly with a control valve attachedto a nozzle system. A support frame and harness stabilizethe unit and attach it to the operator’s back. The pumpdraws liquid from the supply tank and delivers it to thechamber where it is held under pressure until the valveon the wand is opened. The pressure forces the liquidthrough the nozzle which breaks it into small spraydroplets. Because the pressure drops as the flowcontinues, periodic hand-pumping is required.

Knapsack sprayers are very popular and adapt wellto many greenhouse situations. Understanding the safetyfeatures and functional design of your sprayer willenhance its effectiveness.

37

Store the wand in a safe place when not in use.Wands should be equipped with a nozzleappropriate for intended pressures.Wands should have an in line strainer or filter

Construction:Only corrosion-resistant materials should be

used.zzzzzzThe sprayer should be resistant to mildew, rot,and degradation caused by sunlight.Sprayers should be constructed of strong,lightweight material.

Knapsack sprayers provide fairly accurate deliveryif equipped with a pressure gauge or pressure regulator.Nozzles must be designed to work within the pressurerange of the equipment and calibrated for the workingconditions present.

LEVER PRESSURIZED KNAPSACKSPRAYERS with external pressure chambers(Birchmeyer sprayers) can also be used in greenhouseproduction. These systems are well suited to low-volumeand low-pressure foliar applications. The operator needsto pressurize the external pressure chamber onlyinfrequently to produce the proper spray stream.Overpressurizing these sprayers results in a fine, mist-like spray that causes improper coverage and risks off-target drift.

The supply tanks of COMPRESSED AIRSPRAYERS are pressurized either with a hand-operatedplunger or carbon dioxide cartridges.

Compressing air in the space above the spray mixtureforces the liquid through the nozzle. The pressure in thetank drops as the material is applied. This decrease inpressure can be partly overcome by filling the tank only2/3 full with spray material, which leaves ample air spacefor initial expansion. Repressurizing the tank frequentlyalso helps maintain uniform application. Many of thesesprayers lack pressure gauges or controls, makingoperator experience an important factor in consistent

Knapsack sprayers should provide for safe andefficient operation:

They should stand upright for easy filling,cleaning and storing.They should have a carrying handle anddurable, adjustable straps that distributeweight comfortably on any user.Even with a full tank, they should be easy tolift and strap in place.They should have well placed, easy to usecontrols

The tank features:The tank shape should conform to theoperator’s back.The shape should be suitable for rapid andcomplete draining.It should have an adequately sized inlet openingwith basket strainer and a tight fitting cap.The cap should be easily tightened and loosenedby hand.The tank should have an easy to read volumegauge.zzzzThe tank should be equipped with an agitator.The tank should have pressure gauges andpressure adjustment controls.

The pump features:The pump stroke should be a comfortablelength.zzzzNormal pumping rates should producemaximum output.Pumps should be removable for easy servicing.Pump volume should be adequate for a multi-nozzle boom.Pumps should have minimum friction inlinkages.

The wand and nozzle assembly features:Wands should be rigid and strong.A positive shut-off spray control valve shouldbe provided to prevent drips.The wand should be long enough for allintended uses.

38

coverage. These types of sprayers should not be usedfor insecticide or fungicide applications where uniformcoverage is crucial. For sprayers equipped with pressuregauges, the tank should be repressurized when thepressure drops 10 psi from the initial reading.

Powered hydraulic sprayers

Power-operated hydraulic sprayers distribute largevolumes of prepared pesticide by forcing the solutionthrough nozzles. Both the pressure and nozzles usedaffect droplet size and how thoroughly the spray targetis covered.

When complete coverage is not required, as withsoil incorporated insecticides, LOW-PRESSUREHYDRAULIC systems deliver pesticides with a low riskof drift. They deliver low to moderate volumes of spray,usually 10 to 60 gallons per acre, at working pressuresranging from 10 to 50 psi.

HIGH-PRESSURE HYDRAULIC systems arebetter suited for applications where plant surfaces mustbe completely covered, as with protectant fungicides.Air currents produced by the high pressure spray streamdistribute the small droplets on all surfaces of plants.The risk of off-target drift is much greater with highpressure systems. High-pressure hydraulic systems areequipped to deliver large volumes of spray, 20 to 500gallons per acre, under pressures ranging from 50 to 400psi or more. All hoses, valves, nozzles and othercomponents must be designed for high-pressureapplications.

CONTROLLED DROPLET APPLICATORS(CDA) use spinning and oscillating disks to produceraindrop sized sprays. These types of spray applicatorswere developed specifically to reduce off-target drift.They disperse spray droplets using mechanical means,rather than hydraulic pressure. A small volume of spraymaterial under low pressure is converted to a shower of

large, uniformly sized drops as it spins off the edge of arotating disk. Droplet size is controlled by rotation speed.Rotary or raindrop applicators are available for attachmentto booms or to backpack sprayers. Because theseapplicators may be mounted vertically or horizontally, awide range of swath widths is possible. These devicesare expensive but greatly reduce the risk of drift or otheroff-target damage. Their precision makes them usefulfor greenhouse applications.

MISTBLOWERS use a high-velocity, large-volumeair stream to apply concentrated pesticide mixtures. Thegoal of air stream applications is to replace all air withinthe crop canopy with pesticide-laden air from the sprayer.This requires adequate air volume from the equipmentand correct travel speed. Newer designs release the airstream close to plant surfaces, allowing slower speedwhich can reduce drift.

Because the pesticide is carried by air, a limitedamount of water is used to prepare treatments formistblowers. The small volume of water, compared tohydraulic applications, permits greater coverage from asingle fill in less time. In addition, turbulence from theair stream can provide better coverage of plant surfaces.However, mistblowers greatly increase the risk of drift.Only broadcast applications can be made with air streamsystems. Because of the risk of off-target damage,herbicide applications should never be made with airstream applicators.

The most recent ELECTROSTATIC SPRAYERSare much like mistblowers in that they are low volumeapplicators using air to form and propel spray droplets.The major difference is that electrostatic sprayers alsoelectrically charge the droplets. Charged droplets repeleach other and thus avoid collisions which would formlarger drops. In addition, charged droplets

39

are electrically attracted to the target plants which carryan opposite charge. When applied from above, chargedspray droplets moving past the upper leaf surface areactually attracted back to the underside of the leaf.

Electrostatic sprayers atomize the treatment mixture.This means that the droplet size is so small that they aredifficult to see at all. Because of the speed at whichmaterial exits the nozzle and the highly concentratedspray solution, practice and skill are required for properapplication with an electrostatic sprayer. Completecoverage is only obtained by pointing the nozzle directlyat the target plant. Operators should rely on the air streamto move plant leaves and propel droplets through densefoliage for thorough coverage. Evendistribution is obtained if plants are sprayed from twodifferent sides. With each pass of the nozzle, the operatorshould sweep past the plants to promote leaf movement.The atomized pesticide is deposited so finely that leavesmay still appear dry after treatment. Because of this it isdifficult for the operator to see if plants have beentreated. Current manufacturer’s recommendations statethat if the mistblower operator observes plant leavesmoving during the spray operation, then the leaves havebeen treated adequately.

Thermal foggers

These are low volume applicators used in thegreenhouse industry. Thermal foggers use a speciallyformulated carrier that is injected with the pesticide intoan extremely hot, rapid air stream. The air stream isthen propelled into the greenhouse producing a densevapor of very small droplets that penetrate thegreenhouse like an aerosol fog. The rate of applicationdepends on the size of the metering orifice. Thermalfoggers that are designed to treat larger areas have large

tanks and require more time to dispense the greatervolume of pesticide mixture.

Thermal foggers can be carried by an operator,moved on a cart, or operated from a fixed location in thegreenhouse. Effective use of thermal foggers usuallyrequires moving them around the greenhouse. Movingthe fogger gives uniform distribution of spray material.Operating a fogger from any fixed position below thetarget area will deposit most of the material on the floornear the fogger. It is quite easy for an operator to carry afogger and watch the fog’s movement through a roomto ensure good distribution. The fogger nozzle should beaimed at an angle, slightly above the top of the crop.Aiming the fogger nozzle directly at the plant canopymay cause thermal or chemical burns to the plants.

Because the effectiveness of thermal foggers isdependent on room temperature, relative humidity andair flow in the greenhouse. These factors also affect thelength of time between application and safe reentry intothe greenhouse. High temperature and low humidity makespray droplets fall out of the air more quickly than withmoist and cool air.

Mechanical foggers

Mechanical foggers, cold foggers and aerosolgenerators are low volume applicators that atomizetreatments mechanically to generate a cloud of very smallspray droplets. They use external fans to propel the spraycloud toward the target and to promote air circulationwithin the greenhouse. Research has shown thatmechanical foggers deposit more spray material on theupper sides of leaves than on the undersides.

The size of the fan and the capacity of the spraytank determine the size of room that a mechanical foggercan effectively treat. Since most mechanical sprayers

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SPRAYER COMPONENTS

Nozzles

A variety of materials are used to make nozzles,including brass, stainless steel, ceramic and nylon. Thereare advantages and disadvantages with each type ofmaterial. However, it is wisest to invest in the best qual-ity nozzles available. Brass nozzles are relatively inex-pensive, but they wear rapidly with abrasive materials,such as wettable powders and liquid fertilizers. Stainlesssteel and hardened stainless steel are the most resistantto wear, but their expense discourages some users. Fre-quent replacement of brass nozzles usually makes theiruse more costly in relation to the area sprayed.

The smooth surface of nylon nozzles makes themrelatively resistant to wear, but the threads are easilydamaged in use, especially when overtightened. Modi-fied nylon tips in metal housings avoid some of theseproblems. However, some solvents react with nylon,causing the material to swell and become unusable. Ce-ramic spray nozzles are also abrasion resistant, but areexpensive and breakable.

There are different types of spray patterns pro-duced by nozzles each designed for a specific application.Choosing the proper nozzle for a particular treatmentwill ensure good coverage and minimum drift. The se-lection of a nozzle is determined by the type of treat-ment being applied as well as certain aspects of the sprayequipment such as flow rate and operating pressure.Herbicides are applied at low pressure to produce largedroplets that reduce drift. Higher pressures are used withfungicides to produce small droplets for better coverageof foliage. Insecticides are applied with pressure rangesbetween these two extremes. Drift control adjuvantswork best with nozzles that reduce the number of fineand mist-like drops. To be effective and safe, nozzlesmay need to be changed for different pesticide applica-tions.

The different types of fan nozzles are designed towork only within certain pressure ranges. Even slightchanges in spray pressure will alter the pattern producedby a fan nozzle. It is also important that the nozzles areat the proper height above the target. Otherwise the spraypattern will not provide uniform coverage. The requiredheight depends on the nozzle angle and spacing alongthe boom. Refer to manufacturer charts for the correctspacing, height and pressures for various fan nozzles.

The tapering-edge spray pattern produced by flat-fan nozzles provides uniform coverage when overlap-ping nozzles are used on boom sprayers.

are meant to be operated from a fixed position, morethan one may be needed to treat larger greenhouses.

Aerosol bombs / smoke generators

Aerosol bombs or smoke generators contain highlyconcentrated pesticide formulations. They use apressurized propellant to disperse pesticide. Aerosol andsmoke spray clouds are made up of very small dropletsthat provide very good coverage.

Application rates for aerosols are based on thevolume of air in the greenhouse. This is an economicalmethod of treatment for small greenhouses. However,as with foggers, using aerosols and smoke bombs doesnot ensure good foliage penetration or good coverage ofboth leaf surfaces. Using the correct number and properdistribution of pesticide containers will help ensureuniform distribution of the material throughout the entireroom.

Hazards of foggers/fumigants and aerosolbombs

These types of application have a potential forcausing explosions when used improperly. Follow all raterecommendations carefully, especially where ignitionsources exist.

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Even flat-fan nozzles deliver the same fan shapebut the droplet distribution is even across the entirepattern. These are used for banded applications wherespray from adjacent nozzles does not overlap.Applications made selectively over the tops of crops orbetween rows use this type of nozzle.

Flooding fan nozzles used with low pressure producelarge drops in a wide spray angle. These nozzles reducedrift and prevent clogging. Adequate coverage withflooding nozzles requires spray patterns that fully overlap.

Twin orifice flat-fan nozzles are designed forapplications that require good penetration and coverageof foliage. Two small openings in the nozzle direct spraystreams that form smaller droplets using the same lowpressures as conventional flat-fan nozzles. The smallopenings are subject to clogging and require finer strainersthan other nozzles.

Cone nozzles are used for insecticide and fungicideapplications when thorough foliar coverage is needed.Cone nozzles used with high pressure form small,lightweight droplets. Because the risk of drift is greatlyincreased, these nozzles should only be used whencomplete coverage is required. Low volume applicationsare made with hollow cone nozzles that concentrate thespray around the edge of the pattern. Solid cone nozzlesthat evenly distribute pesticide in a circular pattern areused for high volume applications.

Other special purpose and improved nozzles areavailable for use on greenhouse crops. Consultmanufacturer information for the proper selection anduse of nozzles suited to your application needs.

Other components

Flow control devices are necessary to make the tank,pump and nozzles work together. Depending on theapplication system, these devices may include pressureregulators, unloader valves and control valves.

Because both the spray pattern and flow rate aredetermined by operating pressure, each sprayer shouldbe equipped with a pressure gauge. The gauge should beplaced where it may be easily seen.

Strainers are also required for effective treatments.Strainers trap particles and debris in the spray mixtureand protect the pump, control devices and nozzles fromdamage.

CHEMIGATION

Chemigation, or the practice of applying materialsthrough watering systems, requires constant attention tohow the material is applied and to the operation of thewatering system. The chemigation system must be keptseparate from the water supply to prevent anycontamination.

Chemigation with a nozzle watering system must bedone in a manner consistent with the pesticide label.The nozzles must provide the correct total output anddroplet sizes. Nozzle watering systems do not provideadequate coverage of leaf undersides or effective canopypenetration.

The output of a chemigation system should befrequently checked to ensure the correct rate of pesticideis being applied. The output should be measured usingaccurate collection containers.

CALIBRATION

Calibration is the process of measuring and adjustingthe amount of pesticide your equipment applies to thetarget area. It is a routine part of using any applicationsystem. This is not a once-a-year job. It is a good ideato calibrate spray equipment on a regular basis. As aminimum equipment should be calibrated during the firstday of the spray season or when equipment is first putinto use, and whenever nozzles are replaced. Failure tocalibrate pesticide application equipment can result inplant injury, creation of a hazardous situation and wastedmoney. Frequent calibration identifies worn nozzles andkeeps the operator aware of factors that affect application

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rate, such as travel speed, pressure at the nozzle, andtype of nozzle in use. Multipurpose sprayers must becalibrated for each different use.

Calibrating application equipment is not difficult. Besure that all parts are clean and operating correctly andfollow the manufacturer’s directions carefully. Sprayequipment calibration begins by determining three factors:

Correct pump operating pressureType of carrier or diluentSpray volume required

Operating pressure depends on the spray systemchosen. Each pump has a range of pressures in which itoperates most efficiently. Operating within these limitsprovides steady pressure output and protects the spraysystem from damage. The specific pressure to use isdetermined by considering the drift hazard andpenetration recommendations for the pesticide used.

The type of carrier limits the selection of nozzlesthat can withstand the pressure, volume and formulationswithout excessive wear. Low-pressure foliar applicationsoften use water as the carrier. Manufacturers providecharts to assist in selecting the proper nozzles for usewith different types of carriers.The volume of spray needed for effective coverage isstated on the pesticide label. Rates are often expressedas the amount of diluted pesticide mixture to use perarea, such as “20 gallons per acre.” If the applicationrate is given as weight of active ingredient per area, forinstance “do not exceed 20 pounds a.i. per acre,” thevolume of diluted mixture this produces must bedetermined before proceeding.

When a range of acceptable volumes is given suchas “up to 100 gallons per acre” the size of the spray tankand area to be treated will determine the actual sprayvolume to use. Proper coverage of mature plants requiresgreater spray volume per area than younger plants.Application rates for soil-applied herbicides should beappropriate for the soil texture. Over-application to sandyor porous soils can lead to leaching or off-target injuryproblems.

Hydraulic systems

All hydraulic sprayers, including booms and hand-held wands, are calibrated with similar procedures.Because the amount of spray delivered by these systemsdepends on how fast the pesticide mixture flows fromthe nozzle and how quickly the nozzle is moved overthe target area, calibration requires a few calculations.The arithmetic is very straight forward when worked

through carefully. Check the Core Manual for moreinformation.

The first step in calibration is to find the deliveryrate of the nozzles. This is done by pumping waterthrough the nozzles for a timed period, say five or 10minutes, and collecting the spray for measurement.Nozzle flow varies with the size of the nozzle tip and thenozzle pressure. Flow through the nozzle is proportionalto the square root of pressure. In other words, to doublethe flow rate, pressure must be increased four times.An accurate pressure gauge is required to maintain properspray pressure. The delivery rate per minute (in gallonsper minute, GPM, or in ounces per minute, oz/min) isfound by dividing the volume collected by the numberof minutes. Fill the spray tank at least half full of waterwhen calibrating your spray system. (Because residuesfrom spray mixes may remain in the tank, always wearchemically resistant gloves, long sleeves and a face oreye shield while performing calibration steps.)

The recent introduction of calibration tools makes iteasy to measure the flow rate of nozzles. Spray tip testersprovide direct readings of the rate as water is pumpedthrough the nozzles. This eliminates the need for timedcollection and the subsequent calculations.

Hand-held wand calibration

Hand-held wands with single or clustered nozzlesmay be supplied from either knapsack sprayers or powersprayers with larger tanks. Liquid applications made withany hand-held wand can be performed accurately whenpressures, swath width and walking speed are controlled.This means that each piece of equipment must becalibrated for the individual using it. Operators using hand-held wands must develop a uniform speed of applicationand check frequently to assure that a consistent rate ismaintained.

Uniform applications require practice applicationswith water. These can be made to asphalt or concretesurfaces of parking lots, or to strips of wrapping paperplaced in actual field conditions. Uneven applicationscan be noted as the surface dries. Adjust walking speedand repeat the process until sprays are uniform.

To begin calibration, determine the swath width; thisis the width of the row or inter-row space to be treated.Fit the application equipment with the proper nozzle andadjust the pressure to produce the desired swath width.Finally, determine a comfortable walking speed, in feetper second, for the operator. Several passes over ameasured distance of actual field conditions should beaveraged to find the travel speed. Gallons per acre (GPA)is determined with the following formula:

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oz/min X 5.7 GPA = ——————————

ft/sec X swath widthwhere,

oz/min = nozzle output per minute, in ouncesft/sec = walking speed of operator during

applicationswath width = width of row, in feet, treated in

a single pass.This calculation provides the rate of application PER

ACRE of actual treatment. It may be necessary todetermine the amount of pesticide needed for a singlefill of the applicator’s tank and how many refills will beneeded to treat an acre. The following exampledemonstrates the necessary calculations for a knapsacksprayer using the above formula.

Example: An operator wants to apply five poundsof a pesticide per acre as a two-foot wide band ofspray using a four gallon capacity backpack sprayer.The nozzle discharges 38 ounces of solution perminute. The operator walks at four feet per secondwhile making applications. The dilution rate for thepesticide under the given circumstances is found bysubstituting the numbers into the formula:

38 oz /min X 5.7GPA = ———————— = 27 gal /acre.

4 ft /sec X 2 ft

Treating one acre would require mixing five poundsof product with 27 gallons of water. Since the sprayeronly holds four gallons, the amount of product touse per fill is determined as follows:

backpack capacity in galoz /fill = ————————— X oz product /acre

GPA

4 gals= —————— X 80 oz /acre

27 gal /acre

= 11.9, or just about 12 oz /fill.

Note that for this example,

oz product/acre = 5 pounds X 16 ounces/pound= 80 oz

The length of row each fill of the sprayer treats isdetermined using the following formula:

backpack capacity X row length/acrerow length/fill = ——————————————— GPA

where, backpack capacity is expressed in gallons, and,

43,560 sq ft/acre row length/acre = ————————— swath width in feet

Continuing our example, we first determine rowlength per acre,

43,560 sq ft/acreRow length/acre = —————————

2 foot swath

= 21,780 ft/acre.

Now we can complete the calculation,

4 gal sprayer X 21,780 ft/acreRow length/fill = ————————————

27 gal/acre

= 3,226 feet.

And so to make our application at the given rate peracre, nozzle discharge, and walking speed, we will need12 ounces of pesticide diluted in four gallons of waterfor each fill of the backpack sprayer. Each fill treats3,226 feet of row using a two foot swath width. For anacre, the sprayer must be filled seven times (27 dividedby 4 = 6.75).

Mistblowers

It is not possible to collect the nozzle output of airstream sprayers, so calibration begins by determiningthe amount of output over a short period of time. Theequipment is placed on a level area and the tank filledwith water. If the tank lacks calibrated markings, thewater must reach a level that can be duplicated onrefilling. Before beginning, check for leaks around tanksand seals; make sure all nozzles are clean and operatingproperly.

While standing upwind, operate the equipment at itsnormal speed and pressure. Open all valves to the nozzlesand start a stopwatch at the same time. Run the sprayerfor several minutes before closing the valves and recordthe exact time elapsed. Measure the volume of waterneeded to refill the tank to the original level and calculate

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the volume of water sprayed per minute. Repeat thisprocess at least twice and average all runs to determinethe nozzle output. If measurements are made in ouncesper minute the same equations given above may be usedfor calibration.

CLEANING AND MAINTENANCE

While using any application system, be alert forchanges in the spray pattern. Gaps caused by cloggednozzles or spreaders can result in poor control. Wornnozzles can lead to over-application, which increasescosts and may cause excessive residue. Always protectyourself first. Wear all the personal protective equipmentspecified on the pesticide label when repairing ormaintaining spray equipment. This is a wise precaution,even when you think the equipment has been properlycleaned.

Cleaning the application system

Sprayers need to be cleaned to prevent corrosion ofequipment parts and to reduce the risk of crop injuryfrom cross contamination. Trace amounts of one pesticidecan react with another or carry over to the next spraying.With extended contact, small amounts of some pesticidescan damage sprayer components, including stainless steeland fiberglass tanks. Pump components must beprotected from corrosion.

No cleaning method is foolproof. However, carefulcleaning will usually remove all but insignificant amountsof insecticides and fungicides. Herbicides carried overinto an insecticide spray mix could be very damaging tosusceptible crops, such as vegetables. Therefore, twoseparate sprayers, one for herbicides only and one forall other pesticides, are recommended for greenhouseproducers.

When cleaning, the general procedure is to first flushwith water, than add the appropriate cleaning solution tothe tank, agitate and flush again. Always flush with cleanwater to remove any cleaning solution. Remove nozzletips and screens; clean them in strong detergent solutionor kerosene, using a soft brush.

Some pesticide combinations may produce a paste-like coating in the sprayer. Flushing after each load canhelp to remove this. If water alone does not dissolve andremove the buildup, add Stoddard solvent, kerosene oranother low flammable solvent; allow the paste todissolve, then agitate and flush into a collection area ortank for future disposal as hazardous waste. Then

continue general cleaning procedures.A thorough cleaning with the proper solution should

be made whenever pesticides are changed or beforestoring equipment. Contaminated storage conditions cancause more damage to the pump or other componentsthan actual use. The cleaning solution depends on thepesticide to be removed. READ THE LABEL forcleaning instructions or see your Core Manual for moreinformation.

Prevent pesticide contamination

Choose the area used for equipment cleanup carefully.Ideally, the cleanup area should have a sealed, concretefloor and curbing with a sump to catch contaminatedwater and pesticides. Avoid contaminating water suppliesand prevent injury to plants or animals. Do not makepuddles that might be accessible to children, pets, farmanimals or wildlife. The rinse water and cleaning solutionmay be sprayed on a site consistent with the pesticidelabel directions, or disposed of as hazardous waste in anapproved landfill. Avoid discharging all of the cleaningsolution in a small area.

An operator should end the spray application withan empty tank or a minimum amount of pesticide mixremaining. Excess materials can be applied to additionalsites as approved on the product label. Or the tanks canbe drained, with the excess contained and disposed of inan approved manner for hazardous waste. Rememberto completely label any containers holding pesticides orprepared mixtures.

An alternative for handling excess spray mixtures,rinsates from triple-rinsing containers, and waste waterfrom cleaning equipment is to use these materials as thediluent for the next batch of the same chemical. Allcontainers holding such rinsates should be clearly andfully labeled the same as the original container. Storethese with other pesticide products in a secure, preferablylocked, place.

Check the manufacturer’s recommendations foryour sprayer when preparing it for storage. Light oil inthe final flush leaves a protective coating on tank, pumpsand hoses. This is not recommended for sprayers withrubber components. Rubber gaskets, diaphragms or pumprollers swell and weaken when exposed to oil.Automotive antifreeze with a rust inhibitor can preventfreezing and prevent corrosion in case all the water isnot drained from the pump. Read the owner’s manualfor the proper care of your sprayer systems. Alwayswear the proper personal protective equipment whenperforming any cleaning or maintenance activities.

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1. What must be done to properly use hose-endproportioners ?

a. wear personal protective equipmentb. install an antisiphoning devicec. take extra care to prevent spillsd. all of these

2. Backpack sprayers should be equipped with agi-tation.

________True ________False

3. Applicators using lever pressurized sprayers neednot worry about off-target drift.

________True ________False

4. Which type of sprayer is better suited for appli-cations where plant surfaces must be completelycovered?

a. low-pressure hydraulicb. high-pressure hydraulicc. lever pressurized knapsackd. none of these

5. Use of mistblowers greatly increases the risk ofdrift.

________True ________False

6. Thermal foggers can be left in one spot in thegreenhouse and still get total coverage.

________True ________False

SECTION 6 - REVIEW QUESTIONS

Equipment and Calibration

7. Which sprayer type gives good coverage on theundersides of leaves?

a. thermal foggersb. mechanical foggersc. electrostatic sprayersd. all of these

8. Proper nozzle choice is crucial to achieve goodcoverage and minimize drift.

________True ________False

9. Herbicides should be applied at high pressuresfor optimum coverage and drift reduction.

________True ________False

10. Chemigation systems should be combined withthe water supply system.

________True ________False

11. Which are acceptable alternatives for handlingexcess spray mixtures?

a. apply to another site consistent with the pesti-cide label

b. dispose of as hazardous wastec. use as a diluent for the next batchd. all of these

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SECTION 7

Methyl Bromide

Chemical name: BromomethaneAppearance: Clear, colorless gas or liquid when under pressure or refrigeration.Weight:Gas: 3.3 times as heavy as air, tends to sink.Liquid: 14.4 pounds per gallon.Odor: Odorless. Often mixed with chloropicrin which is used as a warning

odorant.Reactivity (relevant to liquid methyl bromide only):

Aluminum: Severe explosion hazard.Magnesium: Severe explosion hazard.Zinc: Severe explosion hazard.

Fumigants are not used very often in New Englandgreenhouses. Most growers avoid the problems discussedbelow by using artificial media. Nevertheless, fumigantsare sometimes used to treat greenhouse soil. Fumigationcan control many pests that may compete with, attackand/or injure the crop such as:

Plant-parasitic nematodes, including root-knot, rootlesion (meadow), and cystSoilborne disease causing organisms, including thefungi Pythium, Rhizoctonia and PhytophthoraWeeds including lamb's-quarters, bermudagrass andquackgrassInsects including wireworms, cutworms and gardensymphylans

FUMIGANTS

Hazards of using fumigants

Most fumigants are highly hazardous materials andmust be used only by individuals trained in their properuse. Many greenhouse operations use steam sterilization

to accomplish the same ends as soil fumigation. Steamsterilization is safer and at least as effective as fumigation.If the grower elects to use chemical fumigants, specializedinformation and training are needed. The purpose of thischapter is to outline that specialized information.

Nature and effects of fumigants

Fumigants are pesticides that reach the target in theform of a poisonous gas. In contrast, smokes, fogs andaerosols are dispersed as very fine particles or clumps ofmolecules. Fumigants disperse in clouds of millions ofsingle molecules of the gas. Fumigants can penetratecracks, crevices and the commodity being treated.Fumigants kill when they are absorbed or inhaled by thepest. Fumigants must be applied in sealed enclosedspaces, since once the gas escapes to the atmosphere itseffectiveness is lost. Fumigants are not long lasting, andonce they are gone, reinfestation can occur.

Toxicity of fumigants

Fumigants are highly hazardous materials and mustbe used only by individuals trained in their proper use.They are highly toxic to plants, animals, and humans.

FUMIGATION

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They are often fast acting, some are odorless and cannotbe seen. As a new pesticide applicator you must becomeknowledgeable about the fumigant you use beforeapplying it. Each fumigant acts in its own unique way,and requires specific knowledge of its hazards and nature.Remember, there are no old careless fumigators.

Inhalation exposure

Acute exposure: Do not breathe vapor. Symptomsmay be delayed anywhere from 1 to 12 hours afterexposure to high concentrations; lower concentrationsresult in less severe symptoms within a period of 12 to24 hours. Reported effects: headache, visual problems,nausea, vomiting, abdominal pain and death.

Chronic exposure: repeated exposure may result inadverse central nervous system effects including muscularpains, speech problems, blurred vision and mentalconfusion.

Skin contact

Acute Exposure: contact with the liquid may causeirritation, burning or tingling sensation, redness andswelling. Large amounts can cause blisters, numbnessand aching pain. Liquid methyl bromide can be absorbedthrough the skin and cause symptoms described underinhalation. Death can occur from absorbing liquid methylbromide through the skin.

Important Note: Do not wear protective gloves,adhesive bandages, tight jewelry, contact lenses, or tightfitting clothes while using methyl bromide. It can be

trapped between the apparel and the skin, causing severesymptoms.

Eye contact

Vapors and liquid may cause transient irritation andconjunctivitis.

Ingestion

Ingestion of liquid is unlikely, however, it can causethroat and stomach irritation as well as the symptomsdescribed under inhalation.

Methyl bromide alternatives

The primary fumigant used for soil treatment ingreenhouses is methyl bromide. However, the EPA haslabelled methyl bromide as a Class I ozone-depletingchemical and it is now being phased out of use. A totalban on domestic production and import goes into effectby the year 2000. Alternatives include chloropicrin,Vorlex, Vapam (metam-sodium), Telone (dichloro-propene), and Basamid (dazomet). All of these chemicalsare highly toxic and their future registration status isuncertain.

There are a wide variety of less toxic alternativesincluding solarization, steam sterilization, soil sterilization,hot water, composting, resistant varieties, Trichodermaseed treatments, microwaves, and more. These less toxicalternatives are best used in combination.

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FUMIGATION WITH METHYL BROMIDE

NOTE: THE FOLLOWING SECTION ON SOILFUMIGATION PERTAINS ONLY TO THE USE OFMETHYL BROMIDE PRODUCTS CONTAININGCHLOROPICRIN AS A WARNING ODORANT

Protective clothing

Methyl bromide may be trapped inside clothing andcause skin injury. Wear loose shirts, long trousers andsocks that are cleaned after each wearing. Do not wearjewelry, gloves or other gas confining apparel. If full-face respiratory protection is not required, wear full faceshield for eye protection when handling liquid. Afterexposure, immediately remove clothing, shoes and socks.Do not reuse contaminated clothing until it is thoroughlydecontaminated. Drenched shoes cannot be adequatelydecontaminated.

Respiratory protection

If the concentration of methyl bromide in the workarea, as measured by a pump detector with appropriatetubes, does not exceed 5 ppm, no respiratory protectionis required. If this concentration is exceeded at any time,all persons in the fumigation area must wear a NIOSH/MSHA approved self-contained breathing apparatus(SCBA) or combination air-supplied/SCBA respirator orevacuate the area. (Examples of approved methylbromide pump-type detectors are Draeger, Kitagawa,MSA, and Sensidyne).

These requirements mean that a minimum of twoSCBA respirators and at least one approved methylbromide detector are required to be available beforemethyl bromide is used. If the fumigation is done out ofdoors the SCBA is not required, but is recommended. Ifthe fumigation is done inside a greenhouse, the SCBAmust be worn when the gas concentration is greater than5 ppm.

Measuring the concentration of methyl bromide isan important part of the fumigation job. The onlydetectors accurate enough to measure 5 ppm are thepump-type detectors listed above. The fumigator musthave one of these and use it if the fumigation is doneinside. Exterior fumigation does not require the testingequipment, but its use is still recommended. Without apump-type detector, there is no other way a fumigator

can be sure the concentration of methyl bromide is safe.Halide detectors can be used to monitor for leaks, but ahalide detector does not measure the concentrationaccurately enough to be approved for entry withoutrespiratory protection.

Soil fumigation

Directions for Methyl Bromide; THESEPRECAUTIONS MUST BE FOLLOWED PRIOR TOSOIL FUMIGATION:

Comply with all local regulations and ordinances.Obtain an application permit from regulatoryagencies as required.Never fumigate alone. It is required by the WPS toalways have a trained assistant with the properprotective equipment, present in case of accidents.Persons in charge of all operations must advise otherworkers of all safety precautions and procedures.In addition, they must instruct their helpers in themechanical operation of the equipment.Check the fumigant delivery system for leaks beforebeginning operation. Two trained and equippedpersons must be present during introduction of thefumigant.During soil fumigation, at least 10 gallons of watermust be readily accessible at the site of application.This water must be potable and in containersmarked “Decontamination water not to be used fordrinking.”

THESE PRECAUTIONS MUST BE FOLLOWEDDURING THE SOIL FUMIGATION:

Two trained persons must be present duringintroduction of the fumigant.

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Do not make application of this fumigant when thereis little or no air movement or when there is anatmospheric inversion.When changing the cylinders, be certain they areturned off and that the fumigant system is not underpressure.

THESE PRECAUTIONS MUST BE FOLLOWEDAFTER SOIL FUMIGATION:

Post all treated areas with WPS warning signs untilaeration is complete and ventilation requirementsare met.Two trained persons must be present during removalof the tarpaulin, if used.Keep all animals and unauthorized people awayfrom the area during removal of tarpaulin, if used.

Pretreatment soil preparation

Plow, rip or otherwise till the soil to the depth towhich effective treatment is required. The soil should beworked until free of clods or large lumps. Residue fromprevious crops should be worked into the soil to allowfor decomposition prior to fumigation. Soil moistureshould be adequate for seed germination. Coarse texturedsoils can be fumigated with higher moisture content thanfine textured soils. For best results, soil should be keptmoist for at least four days prior to treatment. Do notfumigate if the soil temperature is below 50° F. For bestresults, fumigate when soil temperature is 60° F to 80° Fat the depth of 6 inches.

Raised tarp method

Raised Tarp Fumigation Method for Plant Beds and OtherSmall Areas:

Dig a trench around the perimeter of area to betreated, throwing soil to the outside so it can be usedto bury tarpaulin edges after covering.To support the cover and provide a small gas dometo facilitate fumigant distribution place items suchas inflated balloons, crumpled fertilizer bags, orburlap bags stuffed lightly with hay or straw on thesoil surface of the area to be treated.Evaporating pans or vaporizers are used for thevolatilization and uniform dispersion of fumigant.Shallow pans or basins made of plastic or metal,except aluminum are satisfactory. Remember,aluminum poses an explosion hazard and is notcompatible with liquid methyl bromide. Use one

evaporator pan for each 300 to 400 square feet ofarea. Special opening devices are available for useof 1 and 1 1/2 pound cans that combine the openerand evaporative pan functions, and are designed tobe used with all parts under the tarp.For delivery of methyl bromide gas from outsidethe tarp, polyethylene tubing is required. Anchorone end of each polyethylene tube into anevaporating pan with tape or a suitable weight. Thisensures that the liquid will be directed into theevaporating pan.Extend the free ends of the polyethylene tubesoutside of the area to be covered.After the supports and tubing are in place, coverthe area to be fumigated with polyethylene film orother suitable material.Seal by placing the outside edges of tarpaulin in thetrench and covering them with soil. Tamp soil downso edges will not pull loose.Attach a polyethylene tube to the can applicator orcylinder valve outlet and release fumigant. Use acylinder dispenser or scale to meter small amountsfrom cylinders. Fumigant may be vaporized beforeintroduction by means of a commerciallymanufactured heat exchanger, by using a copper coilimmersed in a vessel of hot water or by immersinga can in hot water. CAUTION: Puncture the canwith the device before immersing it in hot water;keeping the outlet pointed up to allow only vapor toenter the polyethylene tube.

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Special instructions for greenhouse soilfumigation

The use of methyl bromide in confined spacespresents a potential hazard to humans and plant life.Special precautions must be taken in order to minimizethis hazard. It is the responsibility of the individualsupervising the fumigation operation to see that all safetyprecautions are strictly observed. Before the fumigationoperation commences, the supervisor of the fumigationjob shall have conducted handler training for all personnelinvolved in the fumigation (handler requirements are partof the WPS), removed all persons from the area whoare not directly involved in the fumigation, and inspectedthe equipment to ensure proper application.

Fumigation of greenhouse soils may be done by anyof the tarpaulin methods described, depending on thegreenhouse size and accessibility to equipment. If a windis blowing, all injection should be made upwind from aprevious injection site. Immediately after tarping andinjection of the fumigant, a qualified person, wearingprotective equipment, should monitor the tarped areawith a halide detector. If excessive leaks are found, thesource of the leak should be resealed immediately.

During this operation, all windows and doors shouldbe open and fans operating to maximize ventilation. Thegreenhouse must be placarded on all entrances to thefumigated area with approved WPS signs and any otherinformation required by labeling.

Reentry into treated areas

After fumigation, treated areas must be aerated untilthe level of methyl bromide is below 5 ppm. Do notenter the treated area without proper equipment beforethis time. Protected workers entering the treated areafor short term tasks (not to exceed one hour in any 24hour period) must be provided with a respiratoryprotection device (NIOSH/MSHA approved self-contained breathing apparatus (SCBA) or combinationair-supplied/SCBA respirator). Only a certified applicatoror trained handler may remove placards.

Potting soil fumigation

Potting mixes including compost, soil mixes, andmanure can be fumigated with methyl bromide.Fumigation should take place outdoors or in a wellventilated area away from desirable plants or occupiedbuildings. The material to be treated should have atemperature of 60° F or higher, be loose, and be moist

enough for good seed germination. To ensure a goodseal, pile the material on a concrete floor or on wetground. Pile to a depth of 18 inches. Piles two to threefeet high can also be treated provided perforations aremade in the pile surface at one foot intervals to assistpenetration. Once the pile has been made, install supportsto hold the cover a few inches above the pile surface toaid in proper fumigant diffusion. Evaporating pans areessential for the volatilization and uniform dispersion offumigant except where a vaporizer is used. Shallow pansor basins made of plastic or metal (except aluminum)are satisfactory for this purpose. For delivery of methylbromide from outside the tarpaulin, polyethylene tubingis required. Anchor one end of each polyethylene tubeinto an evaporating pan with tape or a suitable weight.This ensures that the liquid will be directed into theevaporating pan.

Place evaporating pan(s) with anchored applicatortubing about 30 feet apart on the pile surface. Extendthe free ends of the polyethylene tubes outside the areato be covered. Cover with a polyethylene sheeting orother gas confining material of 4 mil or greater thickness.Seal the edges by burying, covering with moist sand orsoil. Attach applicator tube to the can or cylinder valveoutlet and release fumigant. Use a cylinder dispenser orscale to meter small amounts from cylinders. Specialdevices are available for use of 1 and 1½ pound cansthat combine the opener and evaporating pan functions,and are designed to be usable while entirely under thetarpaulin. At the end of the exposure period, unsealopposite ends of the tarpaulin and allow to aerate for atleast 30 minutes before completely removing the tarp.To avoid phytotoxicity, aerate for 24-72 hours beforeplanting.

Potting mixes in flats may also be treated. Arrangethe flats in loose crisscross stacks no more than 5 feethigh, then cover and seal as described above. Introducethe fumigant at the top and in the center of the stack.Use one injection point for each 100 cubic feet. Aeratefor 24 hours.

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1. Use of sterile growing media helps growersavoid using fumigation.

________True ________False

2. Fumigants provide long-lasting plant protectionfrom reinfestation by disease and insect prob-lems.

________True ________False

3. List three alternatives to methyl bromide.

a.

b.

c.

4. What must be available before methyl bromideis used in a greenhouse?

a. two SCBA respiratorsb. one SCBA respiratorc. one methyl bromide detectord. none of these

5. In emergency situations fumigants may be appliedby one person.

________True ________False

6. Soil texture, temperature and moisture greatlyeffect fumigant effectiveness.

________True ________False

SECTION 7 - REVIEW QUESTIONS

Fumigation

7. All personnel involved with application of fu-migants must be trained, at a minimum, as:

a. licensed applicatorsb. agricultural workersc. pesticide handlers

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The difference between day and night temperatureis as important as the actual temperature values. Theprocesses which produce food for plants to grow anddevelop (photosynthesis) stop working at about 95°Fand above. The processes which make the plant growand develop (respiration) continue at night. At a certainlow temperature (specific to the crop) these processeswill also stop.

Recent research has improved our understanding oftemperature control. Researchers have found that forcertain plant species such as chrysanthemums, lilies, andpoinsettias, high night/low day temperatures will reduceor eliminate the need for application of plant growth regu-lators.

The technique of temperature control of plant heightis based on the concept of average temperature. Theconcept is that plants grow and develop at a rate depen-dent on the average temperature they receive over a 24hour period.

AVG Temp = (day temp X hrs day) + (night temp X hrs night) 24

If plants growth is behind schedule the daily aver-age temperature is raised to speed up development. Ifplants growth is ahead of schedule the daily average tem-perature is lowered to slow down development.

Plant height is influenced by the difference (DIF)between Day and Night temperature:

DIF = Day Temperature - Night Temperature

ABIOTIC DISORDERS

Abiotic disorders are caused by nonliving factorssuch as environmental or cultural conditions. They pro-duce a wide range of symptoms, ranging from a simpleloss of vigor to rapid death of plants. Those causing themost severe damage are the easiest to recognize andcorrect. Because some symptoms can go unnoticed, un-favorable conditions and practices may continue for longperiods. During this time, plants are under stress, whichmakes them susceptible to pathogenic diseases. For ex-ample, if powdery mildew develops on a plant usuallyresistant to this disease, an examination might reveal thatthe plant was consistently over-watered, resulting in highmoisture and humidity in the planting area. In this case,correcting the cultural practice that allowed the patho-gen to become established may be adequate treatment.

The abiotic factors which affect optimum plant per-formance are:

Light, temperature, water and airNutrient levels and balancesPollutionPesticide injuryMechanical injury

In many cases, it is the suboptimal levels of the firstand second factors that lead a plant to disease and insectproblems. For this reason, it is important to be aware ofthe specific needs and sensitivities of each crop.

TEMPERATURE

Generally, the warmer the air temperature, the fastera plant will grow and develop, assuming all other condi-tions are optimum. Plant leaf temperature is a functionof light level and air temperature, and is regulated bytranspiration. Sudden changes in air temperature will af-fect humidity and transpiration rates, and can result intemperature stress.

SECTION 8

THE GREENHOUSE ENVIRONMENT

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A positive difference (higher day than night) willproduce taller plants. A negative difference (higher nightthan day) will produce shorter plants. Plant height canbe decreased by lowering the day temperature and alsoby increasing the night temperature. It can also beachieved by inducing a relatively cooler temperature forthe first two hours after sunrise. DIF affects the lengthof the stem internodes rather than the number of leaves.

A table of Day/Night temperature combinations andtheir effect on average Daily Temperature is includedfor those growers who may wish to experiment with thistechnique (see Table I. Day and Night TemperaturesNeeded to Produce Various Average Daily Temperature).Keep in mind that the threshold temperatures necessaryfor flower induction for specific crops still apply.

For optimum plant performance, it is important toaccurately maintain the desired temperatures with a mini-mum of fluctuation around the set point. High tempera-ture injury results in tissue collapse due to desiccation oroverheating of cellular fluids and is more prevalent onyoung tissues and at leaf margins.

Unless freezing occurs, low temperature problemsare more subtle. Slow growth, chlorosis of the leaves,defoliation, and various nutritional and pathogenic dis-eases often occur after plants are exposed to low tem-peratures. When propagating plants, the soil tempera-ture must be monitored, since the rooting medium isoften cooler than the air temperature due to evaporativecooling. Low temperatures can slow the growth of seed-lings, or the rooting of cuttings. A sudden rise in airtemperature may result in moisture condensing on leafsurfaces, providing conditions favorable to some plantdiseases.

LIGHT

Light intensity, quality, and duration are importantfor optimum plant growth and development. Generally,plants grow more with blue light because each unit ofblue light contains more energy than red light. Plantsneed red light for timing their daily and seasonal clocks.Many growers have successfully used supplemental light-ing to increase the light intensity during cloudy days andduring the fall, winter and spring. (See Table II - Com-mon Supplemental Light Intensities for Various Orna-mental Crops for more information.)

Greenhouse plants may be divided into two broadgroups: those tolerant of full sun, and those requiringpartial shading. Insufficient light levels can result in poorcoloration, leggy growth, and slow development. Exces-

sive light results in bleaching of foliage and, in severecases, high temperature injury, since light radiation raisesthe leaf temperature. Proper spacing, timely watering,and shading when necessary can correct high light prob-lems.

The acclimatization of tropical plants to maintenancelevels is done over a 3 - 6 week period. This involveslowering the intensity and adjusting the duration of lightto similar levels encountered in indoor plantings. Whenplants do not undergo this gradual change, leaf yellow-ing and leaf drop usually occur. Acclimatization also re-quires adjusting the fertilizer rates to 10 - 20 percent oforiginal levels and adjusting soil moisture according tothe size of plant, ambient humidity, air movement andtemperature.

WATER

The moisture requirements of plants are closely tiedto light and temperature factors. Potting mediums shouldbe well drained. Underwatering encourages salt accu-mulation and may lead to serious damage when plantswilt during bright, hot weather. Overwatering is a com-mon cause of root disease. Roots are unable to obtainenough oxygen in a constantly saturated media. Thisleads to tissue death which provides an entry site forplant pathogens.

The initial nutrient, salt, pH, alkalinity, and sanitarylevels of water supplies must be given consideration be-fore developing a watering and fertilizing program. Wa-ter analysis should form the basis of any such program.

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Watering practices

Overwatering can lead to plant disease problems,poor soil aeration, wet soil beneath benches, standingwater and more. Algae and fungi growing in these moistareas and on accumulating organic matter lead to prob-lems with fungus gnats and shore flies.

Conversely, plants that are under water stress areoften more susceptible to insect and mite problems. Spi-der mites, in particular, favor dry environments. Carefulattention to watering practices can reduce pest problems.

Plants are 80 to 90 percent water. The water in planttissues holds the leaves and stems erect and is essential

for cell division and growth. Movement of water fromthe roots to the leaves circulates nutrients, removes wasteproducts and helps cool the plant. Excess water is justas hazardous to plant health as lack of water. Over- andunder-watering result in 85 percent of indoor ornamentalplant losses.

The problem of excess water

More plants are killed by excess water and poordrainage than by any other cause. The high rate of res-piration and growth in the roots requires a constant sup-ply of oxygen in the growing medium. Two situations

55

long periods. As long as the foliage is not wetted, thetime of day plants are watered does not contribute todisease.

Apply enough water to allow at least one-tenth todrain from the container. This leaching of the soil carriesaway excess fertilizers and soluble salts that could buildup in the growing medium. It is necessary to water theentire surface of the growing medium each time; waterflows down through the soil with little sideways move-ment. Frequent, shallow watering may be harmful be-cause most of the subsurface soil is left dry. Plant healthis improved when each container is watered thoroughly,but less often.

Quality of water

Water safe to drink is adequate for watering plants,except it should not be softened. The sodium used toreplace calcium in hard water injures plants. High so-dium levels also break down soil structure. Hard waterdoes not harm plants, but excess soluble salts need to beleached from the soil occasionally.

Some city water systems add fluoride to drinkingwater supplies. When used on foliage plants, a few sen-sitive species show tip burn and other symptoms as fluo-ride levels build up in the soils. Chlorine gas used tomake drinking water supplies safe does not generallypresent a problem to plants. Enough chlorine escapesinto the air during watering that little threat to plantsoccurs. Deionized water is also suitable for applicationto plants.

PLANT NUTRIENTS

There are 17 chemical elements essential for planthealth. Carbon, oxygen and hydrogen are readily avail-able to plants from air and water. The other 14 nutrientsare absorbed from the growing medium by the roots.When the natural soil nutrients are depleted, fertilizersreplace the missing elements and maintain plant health.

exclude oxygen from the root area. The first is a resultof soil characteristics. Poorly drained soils retain waterin all pore spaces, directly blocking out air. The other isthe result of improper watering. When too much wateris applied, the excess drains from the container, but amoisture layer remains on the smallest roots. This actsas a barrier to oxygen absorption.

Evidence of over-watering may take a month or moreto appear after the soil is flooded. As roots die due tolack of oxygen, apparently healthy leaves begin to die.Foliage loss continues until the leaves are reduced to thenumber the remaining roots can support.

Overwatering problems are avoided by wateringplants only when needed, not on a predetermined sched-ule. Good judgment is required to determine not onlywhen to water, but how much. If there is any doubt, it isbetter to err on the side of dryness and withhold water.

Knowing when to water plants

An experienced worker can tell when to water bystroking a plant’s foliage. Crisp, rigid leaves indicate ad-equate moisture is still available. Knowing the dry weightof small movable planters and pots provides a hint to thewater content. Soil color is also a clue to the moisture itholds. These skills are usually gained through long expe-rience with plants.

The best watering schedule is determined by prob-ing the soil, either by hand or with a small tool. The goalis to determine when soil moisture is nearly depletedand needs replacing. Test three spots in each containerby plunging the thumb and index finger, up to the sec-ond joint, into the growing medium. Wear gloves to avoidexposure to residual chemicals in the potting medium.By squeezing a pinch of soil, an experienced worker cangain a good indication of the water content.

If the pinch of soil drips, it is too wet

If it holds its shape, it is properly moistened

If it crumbles, it is too dry

How to water

It is best to apply water by hand, not with automaticsystems. Individual plant needs are met only when eachcontainer is personally tended. A water breaker nozzleor wand aerates the water and breaks it into rain-likedrops. A fogging nozzle maybe used when misting isnecessary. Hand application permits the use of these toolswithout wetting the foliage of sensitive species. Thechance of disease increases whenever foliage is wet for

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57

Six elements are required in large amounts to buildplant cells and to form the compounds that carry outplant processes. These are called macronutrients due tothe high demand by plants. The use of these nutrientssoon depletes the growing medium of nitrogen, phos-phorus and potassium. These three elements are the pri-mary macronutrients. The secondary macronutrients in-clude calcium, magnesium and sulfur. These are requiredin relatively large amounts but are not depleted as quicklyas the primary macronutrients. “Complete” fertilizers sup-ply only the primary macronutrients (often listed as sim-ply N-P-K) and not all nutrients as the name suggests.

Nitrogen is used in greater amounts than other nu-trients. It has a major role in growth and reproduction.Deficiencies are indicated by yellow leaves and general

poor health of plants. Nitrogen excesses result in poordisease resistance and weak growth. There are two formsfor application; ammonium nitrogen and nitrate. Nitrateis easily leached from soil, but is replaced by vitrifica-tion of the ammonium form. Fertilizers with both formsin equal amounts provide a continuous source of nitro-gen to plants.

Phosphorus is essential for all plant growth. Adequatesupplies hasten maturity, influence good root develop-ment and aid in the use of other elements. Leaching isnot a problem because it binds tightly to soil particles,however this makes it unavailable to plants. Superphos-phate is often used as a soil additive before planting toprovide adequate quantities. High fluoride levels in su-perphosphate can result in tip burn of sensitive species.

Table III. ROLE OF NUTRIENTS IN PLANT HEALTH AND DEFICIENCY SYMPTOMSCHEMICAL ELEMENT FUNCTION IN PLANTS DEFICIENCY SYMPTOMS

MACRONUTRIENTS - Required in relatively large quantities

Nitrogen (N) Basic component of most compounds Stunting, loss of vigor. Leaves yellowfrom proteins to light gathering in general or between veins, older first.pigments.

Phosphorus (P) Important in cell division, flowering, Stunting, dark green leaves. Olderfruiting and root development. veins turn purple or red.

Potassium (K) Involved with stomata opening and Small plant size, leaf tips and marginsclosing. Affects uptake and lose color, turn brown. May lose oldtransport of minerals. leaves.

Calcium (Ca) Forms cell walls. Maintains structure Death of stem tips, poor root growth.of soil, availability of other minerals. Leaves turn brown and fall.

Sulfur (S) Important for respiration functions. General loss of green; plant pale, butPart of aromatic oils formed by not dry.some plants.

Magnesium (Mg) Component of pigments. Behaves Old leaves lose color between veins.much like calcium in soil. No dead spots occur.

MICRONUTRIENTS - Needed only in small or trace amounts

Iron (Fe) Essential in pigment production. Yellow color between veins that remainAids respiration. green, worse on new growth.

Zinc (Zn) Essential for formation of growth New leaves small, narrow, pale.hormones. Generalized leaf spots.

Manganese (Mn) Assists in chemical reactions. Looks like low iron, but wider greenlines next to veins. Spots develop.

Boron (B) Aids water absorption and sugar Stunting, new growth deformed. Tiptransport. may die.

Copper (Cu) Assists in chemical reactions. Young leaves look wilted, deform tocup shape. Color loss between veins.

Molybdenum (Mo) Aids uptake and use of nitrogen. Stunting, leaves become mottled andcurl inward.

Chlorine (Cl) Activates chemical reactions. Plants prone to wilt. Dry, bronze-colored spots on leaves.

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Potassium is important to the movement of foodand nutrients within the plant. It helps maintain overallvigor and promotes root formation. Potassium require-ments are not as great as nitrogen; any deficiencies areeasily corrected by using any complete fertilizer.

Commercially prepared ‘complete feed’ fertilizerscontain N-P-K and trace elements. Usually the trace el-ements in the mix will be sufficient to produce a goodcrop. Iron, in some cases (especially if the media has apH greater than 6.5), may need to be supplemented.NOTE: These fertilizers may not contain calcium andmagnesium in sufficient levels to satisfy plant needs. Gen-erally, premixed fertilizers will have to be supplementedwith calcium nitrate and Epsom salts or magnesium ni-trate. Dolomitic limestone in the media will also supple-ment calcium and magnesium levels. Some complete feedfertilizers have been introduced that contain higher lev-els of secondary elements or micronutrients, for example,magnesium and molybdenum, thereby reducing the needfor supplements.

Nutrient ratios are equally as important as the actualvalues in the media. Some nutrients interfere with orpromote the uptake of other nutrients. For example, thecalcium:magnesium ratio should be maintained at 1:0.4for optimum uptake of both nutrients. Other nutrientratios influence plant growth. A nitrogen:potassium ratioof 1:1 will generally produce normal growth and heightdevelopment, whereas a nitrogen:potassium ratio of 5:8will often produce darker, shorter plants.

Another point to consider is that vegetative growthrequires relatively more calcium and nitrogen while plantsthat are actively flowering require more phosphorus andpotassium.

Micronutrients

Of the 17 essential elements for proper plant growth,8 are required in very small amounts. These are themicronutrients which include iron, boron, manganese,zinc, sodium, copper, chlorine, and molybdenum. So-dium and chlorine are sufficiently available in root me-dia or as fertilizer contaminants. The other six micronu-trients must be applied in fertilizer applications. Some ofthese become a small part of important biochemicals.Iron, for example, has a central role in the structure ofchlorophyll. Other micronutrients assist chemical reac-tions without becoming part of plant tissues. Thus, theelement copper participates in important reactions dur-ing plant respiration but is usually not absorbed by planttissue.

There is a fine line between micronutrient deficiencyand levels toxic to plants. Deficiencies of most micronu-

trients are unlikely to occur when a growing medium isbased on natural soil. Special mixtures of these nutrientsare available for the occasional need. Soilless growingmedia require application of all elements before use. Theorganic portion of some mixes can compete for micro-nutrients, as well, making routine fertilization necessary.

Deficiencies and Excesses in an IPMSystem

A plant’s health and performance is dependent onthe availability of the necessary macronutrients and mi-cronutrients. Some crops require more of certain ele-ments than others. For example, poinsettias are knownto require molybdenum in higher quantities than mostother crops. Micronutrients, especially copper, molyb-denum, and boron can reach toxic levels fairly quicklythrough over application.

Nutrient deficiencies often result in slow growth andpoor leaf shape or coloration. Excess nitrogen producessoft leaf tissues which are more susceptible to foliar dis-eases such as Botrytis. Chrysanthemum leafminers ap-pear to be attracted to plants grown with high nitrogenlevels. Nutritional deficiencies or excesses may be avoidedby checking feeding formulas and verifying that all 12 ofthe required elements are available in the correct quanti-ties. Ensure that the correct amounts of fertilizers areincorporated into potting mixes. A soil test may be nec-essary. A simple test of pH and conductivity can oftenindicate if soil conditions are adequate. Tissue analysiscan be used to determine the levels of elements actuallypresent in a plant and to verify fertilizer imbalances. (SeeTable III - Role of Plant Nutrients in Plant Health andDeficiency Symptoms for more information.)

IMPORTANCE OF pH

The acid or alkaline nature of soil is measured onthe pH scale, which ranges from 0 to 14. Neutral com-pounds, such as distilled water, have a pH of 7. Acidshave a lower pH; alkaline substances, a higher number.Most indoor ornamental plants grow best in slightly acidsoils, in the range of pH 5.5 to 6.5.

Soil pH should be adjusted, if necessary, beforeplanting. Adding lime, in the form of dolomite or cal-cium carbonate, will raise the pH of an extremely acidsoil. Sulfur compounds are used to lower the pH of al-kaline soils. The amount of amendment needed to reachthe desired pH depends on the starting pH and theamount of organic material in the soil mix.

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FERTILIZATION PROGRAMS

A well managed fertilization program provides ad-equate nutrients to the plants at all times. Too little ortoo much in the growing medium impairs plant health.Excess fertilizer will not make a sick plant healthy andcan kill a plant suffering from other problems.

Fast growing plants in production greenhouses havehigh nutrient demands. These are met with frequent fer-tilizations and the use of slow release fertilizers. Onceplants are placed in landscapes, their nutrient needs aregreatly reduced. The high levels of fertilizers used inproduction can be harmful to plants under low light con-ditions.

Fertilizer applications should be timed to the growthcycle of plants. Many plants go through a period of dor-mancy when there is little growth. Chemicals appliedduring this time are of little use to the plant and mayresult in harmful excesses. Most plants have a period ofactive growth through the spring and summer. Not onlyare light levels higher, but increased temperatures en-courage greater plant activity. Nutrients should be readilyavailable in the soil at this time. This is particularly im-portant when lighting systems rely heavily on naturallight.

Forms of fertilizers

Several forms of fertilizers are available for use onindoor ornamental plants:

Liquid, must be diluted before use

Soluble crystals, dry salts that dissolve in wa-terzzzzz

Release of nutrients from fertilizers and their avail-ability to the plants is controlled by soil pH. If the pH istoo low (acidic), the conversion of ammonia nitrogen tonitrate is slowed down. When pH levels are high (alka-line), micronutrient availability is reduced. Routine useof most fertilizers lowers the soil pH. Soil testing for pHand nutrient levels is part of a well managed plant main-tenance program. Testing should be routinely scheduled.

A comparison of two products (in 10 pound bags) with different N-P-K analysesProduct A Product B

N-P-K is 30-10-20 N-P-K is 15-5-1030% of 10 # = 3 # N 15% of 10 # = 1½ # N10% of 10 # = 1 # P 5% of 10 # = ½ # P20% of 10 # = 2 # K 10% of 10 # = 1 # KTotal N-P-K = 6 #N Total N-P-K = 3 #Filler = 4 #N Filler = 7 #

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Tablets, soluble forms in easy-to-measure tab-letszzzzzzSlow release, granules or plastic-coated formsthat release nutrients over several months

Organic, materials that release nutrients at lowrates over long periods of time

Fertilizer can be a major expense. The form chosenis not important as long as the required nutrients areprovided. Complete fertilizers list the percent of nitro-gen phosphorus and potassium in a standard format. A30-10-20 fertilizer means that 30 percent of the com-pound is available nitrogen, 10 percent is phosphorusand 20 percent potassium. A fertilizer with an N-P-Kanalysis of 15-5-10 has the same relative amounts ofnutrient (3 parts nitrogen: 1 part phosphorus: 2 part po-tassium), but lower amounts available per pound.

Other factors that influence selection of a fertilizerinclude the form of nitrogen, chemical purity, solubility,effect on pH, uniformity, ease of handling, personal ex-perience and price.

Application rates

Fertilizer recommendations are developed for theideal growing conditions of a greenhouse; applicationrates are related to the light available to plants. Plants inmost greenhouses need only one tenth or less of theamount needed under full growth conditions.

Frequent applications of reduced rates provide nearlyconstant nutrient levels. Low application rates also main-tain plant health without encouraging excessive newgrowth. Routine soil testing in necessary to develop aschedule suited to each maintenance site. When fertili-zation is required, select a formulation intended for green-house use. Always READ THE LABEL before appli-cation and make sure other requirements are met. Applyonly to active plants, and not during dormancy.

Nutrients are soluble chemical salts. When dissolvedin the soil water, they compete with root hairs for mois-ture. Diluting formulations to one-half (or less) of therecommended rate reduces the chance of over-fertiliza-tion. As long as chemical concentrations are higher inthe roots, water moves into the plant. When high levelsof salts occur in the soil, water fails to move into theroots as easily. “Fertilizer burn” (where leaves lose colorand turn brown) is evidence of this condition. Excessnutrients can occur from a single overapplication, or fromone or more of the following:

Excessive fertilizer applications

Improper watering schedule and methods

Use of hard water with naturally high salt levels

Poor soil drainage

Drying out of soil on concentrated fertilizer pro- gram

Using soils with high fertilizer retention

Leaching soils helps reduce high soluble salt con-centrations. Recurring problems require changing otherfactors contributing to the high levels.

AIR

Adequate ventilation and air circulation can reducethe incidence of many foliar diseases. The humidity inthe air is crucial to the health of plants. Humidity levelsmust often be reduced in greenhouses to avoid watercondensation on leaves and flowers. High humidity lev-els can result in guttation and edema.

Guttation occurs in some species as a seepage ofcellular fluids from the margins or edges of leaves. Al-though guttation may not harm the plant, it can indicatea humidity problem, and favors the development of bac-terial diseases.

Edema is a disorder brought on by wet conditionsand high humidities. Cells rupture due to excessive tur-gor pressure (internal plant water pressure), creating cal-loused corky spots on the undersides of leaves and some-times on the stem. Ivy geraniums are especially sensi-tive.

In addition, certain minerals such as calcium, whichmove only through the water conducting xylem tissues,may not be translocated efficiently under excessive airhumidities.

READTHE

LABEL !

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Carbon dioxide (CO2) is essential for plant growth.Next to water it is the nutrient used in the greatest quan-tities by the plant. Plants will stop growing when theCO2 concentration drops below 180 - 200 ppm. CO2can be supplemented to 1,000 ppm whenever daytimeventilation is reduced. Under very low light conditionssupplemental CO2 will have a minimal effect on plantgrowth. There may be an economic advantage to supple-mental CO2 at 350 - 400 ppm during periods of ventila-tion as canopy CO2 levels can drop to 200 - 250 ppmwhen the greenhouse is fully vented. CO2 burners canbe placed overhead but the best location is to inject CO2at the crop level. It is highly desirable to control CO2levels with an automatic controller. Utilization of a timeclock system does not provide precise control for opti-mum production. Some sensitive species may be dam-aged by CO2 levels above 2,000 ppm. Humans shouldnot work in levels exceeding 5,000 ppm.

POLLUTION

Pollution of soil, air, or water is an occasional causeof greenhouse plant disorders. Symptoms can be con-fused with those produced by plant pathogens. Air pol-lutants can harm plants, even when levels are so lowthat no threat to human health exists. Some of the pol-lutants which may cause problems are sulphur dioxide,ozone, PANs (peroxyacyl nitrates), carbon monoxide,and ethylene.

Small amounts of ozone can be produced from metalHalide and VHO florescent lights. Ordinarily this willnot be a problem unless the growing structure has a lowair exchange rate and lights are placed close to the foli-age. Some brown flecking due to ozone may appear ontender bedding plant seedlings grown close to VHO fluo-rescent lights.

Carbon monoxide (CO) injury can occur when im-properly installed oil or gas heaters are used. CO is col-orless and odorless and is a severe health risk to hu-mans.

Ethylene damage can be associated with incompletecombustion of propane or natural gas, or an excess ofsenescing vegetation. Operation of gasoline engines suchas those found on some sprayers in greenhouses canproduce injurious levels of both carbon monoxide andethylene. Symptoms vary from burning of flowers andfoliage to twisted, deformed or ‘blind’ growth. Manyplants, orchids and ferns in particular, are sensitive tovery small amounts of ethylene in the air. This gas isreleased when gasoline or oil is burned; it is also pro-

duced by plant tissues, such as ripe apples. Ethyleneinjury symptoms include leaves bending down at thestems, the yellowing and dropping of older leaves andslowed growth. In addition, blooms develop abnormallyon flowering plants, or buds fall without opening.

A few crops, such as calathea, cordyline, dracaena,freesias, gerberas, gladioli, lilies, maranta, tulips, andzebrina, are sensitive to fluorides which are sometimesfound in water supplies, certain fertilizers, and soil ag-gregates (e.g. some perlites). Avoid using high fluoride0-46-0 (superphosphate) in media mixes. Calcium hasbeen utilized to tie up fluorides.

Cleaning agents can produce fumes harmful toplants. This is particularly true of harsh chemicals usedto clean floors or carpets. Fumes from commercialstrength ammonia can blacken foliage and cause plantdeath. Other symptoms produced by exposure to toxicfumes include loss of foliage or curled leaves.

Plants installed near indoor pools can be damagedby chlorine that escapes into the air. Symptoms includebleaching of leaves and dying of plant tissues. Heavytobacco smoke can harm plants by settling on leaf sur-faces and blocking the pores used for gas exchange. Evenconcentrated fumes from paint or varnish will injureplants. Proper ventilation usually prevents harmful gasesfrom reaching toxic levels.

Wood treated with creosote or pentachlorophenolshould not be used in containers or around planting ar-eas. Fumes from these wood preservatives can injure orkill plants. Early symptoms are bleaching of foliage andyellowing along leaf edges. Wood treated with copper orzinc napthanate (Cuprinol) can be used around plants.

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PESTICIDE INJURY TO CROPS

Given the right circumstances, almost any pesticidecould injure any plant. Greenhouse pesticides are for-mulated to be as safe as possible to target crops, butinjury to certain varieties or species may occur.

Spray injury can occur as marginal or complete leafburning, leaf spots, flower spots, or distorted growth.Damage from drench materials may also produce rootdeath, resulting in sudden wilting, and sometimes thedeath of part or all of the plant.

Misuse can be a cause of pesticide damage to plants.Some common causes are overapplication (too muchchemical or too frequent); application to wet foliage (es-pecially with fumigants); improper timing; and applica-tion to nonregistered crops.

The following precautions can minimize pesticideinjury problems:

1. READ THE LABEL - be sure of the proper use,application rates, and methods of applying the product.Labels often specify varieties and species that may beharmed.

2. CHECK THE FORMULATION - the specificformulation of a pesticide as dusts, wettable powders,emulsifiable concentrates, etc., can affect its safety toplants. If you use a new formulation of a familiar prod-uct, test it on a small group of plants first.

3. TIMING - the state of plant growth is an impor-tant consideration for a pesticide application. Young seed-lings and flower parts are generally more susceptible toinjury than are vegetative phases of growth.

4. PLANT ENVIRONMENT - plants may be moresusceptible to pesticide injury when under stress. Injurymay also occur when pesticides are applied to wet foli-age. A good time to spray is often in the early morningor late afternoon. Pesticides should not be applied whentemperatures exceed 77 - 86°F.

5. TESTING - before using a new material or mix-ture, or whenever a new pesticide is being used on acrop, it is a good idea to test it on a small number ofplants. If no symptoms occur within a few days, it islikely safe for crop use.

MECHANICAL INJURY

Plants can be severely damaged through mishan-dling. Seedlings are particularly susceptible to injury dur-ing transplanting, so care must be taken to avoid stemand root damage.

Improper watering practices such as too much pres-sure, or volume, and the application of excessively coldwater can be very damaging. Fans can cause damage ifthey cause a lot of whipping about and desiccation offoliage.

Plants are usually capable of recovering from somedegree of mechanical injury, however, it may serve as astarting point for further problems including infections.By using common sense in avoiding injuries, it is pos-sible to prevent a lot of further problems and expense.

63

1. Which are abiotic disorders?

a. fungal diseasesb. pollution injuryc. pesticide injuryd. all of these

2. Temperature controls can reduce or eliminate theneed for plant growth regulators.

________True ________False

3. What does DIF equal?

a. night temperature - day temperatureb. day temperature - night temperaturec. day temperature + night temperature

4. Night time temperatures higher than daytime tem-peratures result in taller plants.

________True ________False

5. Which conditions may be caused by insufficientlight?

a. poor colorationb. leggy growthc. slow developmentd. all of these

6. What is acclimatization?

7. Which of these pest problems can be seriouslyaffected by watering practices.

a. fungus gnatsb. shore fliesc. spider mitesd. all of these

8. Which factor kills more plants than any other?

a. insectsb. fungic. excess waterd. lack of water

9. Evidence of over-watering may take a month ormore to appear after the soil is flooded.

________True ________False

10. Water softening and fluoridation can presentproblems to plants.

________True ________False

11. Which element is a primary macronutrient?

a. calciumb. copperc. potassiumd. all of these

12. Soilless growing media is rich in micronutri-ents.

________True ________False

SECTION 8 - REVIEW QUESTIONS

The Greenhouse Environment

64

13. List two pest problems that may be aggravatedby over application of nitrogen fertilizers.

a.

b.

14. What is the optimum soil pH range for mostplants?

a. 4.5 to 5.5b. 5.5 to 6.5c. 6.5 to 7.5d. 5.0 to 6.0

15. Sulphur is added to soil to increase the pH.

________True ________False

16. Under low light conditions more fertilizer shouldbe applied to keep plants healthy.

________True ________False

17. Improperly installed heating systems can releasegases that may damage plants.

________True ________False

18. Which of these precautions can minimize pesti-cide injury problems?

a. proper application timingb. no applications when temperatures exceed 77° -

86°Fc. testing a new mixture on a small number of plantsd. all of these

65

SECTION 9

An aphid nymph

The most common greenhouse aphid species is thegreen peach aphid, Myzus persicae, although recentlythe melon aphid, Aphis gossypii, has increased infrequency. The green peach aphid attacks a wide varietyof floral crops. Its color can vary from light green torose. Melon aphids attack fewer plants includingchrysanthemums and hibiscus. Their color may vary fromlight to very dark green. The chrysanthemum aphid,Macrosiphoniella sunburn, is only found onchrysanthemums and varies from dark red-brown toblackish-brown.

Correct identification is important for efficient aphidcontrol. For example, pyrethroid insecticides may be veryeffective against chrysanthemum and melon aphids butnot against green peach aphids.

Because color can vary within a species so much,color alone is not a reliable indicator for aphid identifica-tion. Positive species identification of most aphids re-quires a l0x hand lens or, preferably, a dissecting micro-scope. Your Cooperative Extension office can assist youwith aphid identification.

Aphids are commonly encountered on many floralcrops, and their presence alone can decrease the aes-thetic value of a plant. These insects feed by insertingtheir mouth parts through plant tissue and removing plantsap. They tend to move to new host plants and activelysearch for soft, fresh plant tissue to feed upon. Theyalso may be found feeding on buds, stems, and the lowersurfaces of leaves. Their feeding can lead to plant stunt-

GREENHOUSE PESTS

Floricultural crops are attacked by many pests suchas insects, mites, slugs, and snails. Although it is beyondthe scope of this publication to deal with every pest onan individual basis, information on pest identification,type of damage, biology, and management strategies aregiven for a few of the more common pests. Your countyCooperative Extension office can help you identify thesepests and recommend appropriate control measures.Apply chemicals only to crops for which their use isregistered and stated on the label. Pesticides used insidegreenhouses must be labelled specifically for greenhouseuse. See the current New England GreenhouseFloricultural Crop Pest Management and GrowthRegulation Guide for specific pesticide materials.

Growers with successful pest management programsknow how to identify the common pests. Theyunderstand pest biology and they recognize the damageeach pest can cause. Successful growers have their pestscouting and management strategies planned before cropproduction begins so they can identify and respond toan infestation quickly and effectively. They also keepabreast of new developments in pest management.

Crop production should start with a greenhouse asfree of pests as possible. Incoming plant material shouldbe inspected for pests or signs of pest damage. Infestedplants should be refused or isolated for treatment.

Pests enter the greenhouse in a variety of ways. Aweekly routine of scouting plant material throughout allgrowing areas for signs of pests and their damage canhelp detect infestations when they are still small andmanageable. A 10X hand lens and insect traps, such asyellow sticky cards, are quite useful for weekly scouting.

APHIDS

Aphid species differ in size, coloration, and foodpreferences. They are all generally small (1 to 3 mm)and soft bodied. Within each species, individual aphidsmay or may not have wings.

66

Sanitation is a vital part of aphid control. Carefullyinspect plant material brought into the growing areas; donot purchase infested plants or cuttings. Eliminate allweeds in or near the greenhouse; they can serve as areservoir for migrating insects or for insects carried byants.

Melon aphid, Aphis gossypii.

Applications of insecticidal soaps and highly refinedhorticultural oils can provide effective aphid control insome cases and should be evaluated by growers. Thesepesticides kill exclusively by contact. Soap kills primarilyby disrupting insect membranes; oil kills primarily bysuffocation. Neither material gives residual control, thusthorough coverage is crucial. It is very unlikely thataphids will develop resistance to these insecticides. Thelack of resistance problems, coupled with low mammaliantoxicity and compatibility with natural enemies, makethese insecticides worth using. Label directions shouldbe followed carefully to avoid plant damage.

Insecticide resistance can vary from greenhouse togreenhouse, and aphid strains with various levels ofresistance to various chemicals may be introduced viaincoming plant material. Therefore, it is difficult togeneralize about the efficacy of a particular insecticide.By keeping careful records and scouting for aphidpopulations on a regular basis, growers can evaluate theefficacy of various chemicals under their own conditions.

To aid in evaluating insecticide efficacy, mark severalaphid infested plants with flags or flagging tape, and recordan estimate of the number of aphids on each. Severaldays after insecticides are applied, the number of survivingaphids should again be recorded. Examine plants carefullyand frequently to determine if repeat applications arerequired. It may be necessary to treat an infestation asoften as twice a week.

Insecticides that have systemic properties tend to bemore effective than contact insecticides for green peach

ing and deformities. Large numbers of aphids can re-move enough nutrients from a plant to affect its vigor.Aphids excrete a sweet, sticky substance called honey-dew. This secretion makes leaves shiny and sticky andcan also serve as a food source for a fungus known assooty mold. Aphids may devalue a crop with the whitecast skins they leave

Green peach aphid, Myzus persicae.

behind as they molt from one life stage to another. Lastbut not least, aphids are responsible for the transmissionof about 60 percent of all plant viruses on agriculturalcrops worldwide.

Aphids produce eggs only under short-day conditionsin the fall. However, during most of the season aphidscan give birth to live young in as few as 7 days withoutmating or egg production. This allows their populationsto increase explosively.

Aphid management is much more successful whenan infestation is detected and controlled early in a cropproduction cycle. Not only are aphids fewer, butphytotoxic damage to blossoms can be avoided.Therefore, a regular scouting and monitoring program isessential.

To successfully monitor aphid populations, it isnecessary to inspect plant foliage at least once a week.Several plants on each bench throughout the greenhouseshould be checked, particularly those varieties on whichaphids seem to occur most frequently. Aphids can bespread on clothing, so plants located near walkways anddoors should be included. Stems and lower surfaces ofall leaves on each plant should be examined. A map ofinfested locations can help target areas to be sprayedand monitored.

The use of yellow sticky cards may provide an earlywarning of aphids in the greenhouse, particularly in thespring and summer. Winged aphids that are activeoutdoors during these times often invade the greenhouse.

Nymph Wingless adult

Winged adult

Nymphs

Winged adults

Wingless adult

67

aphid control, provided a sufficient amount of insecticidereaches the aphid feeding sites. Contact insecticides,however, may be very effective against other aphidspecies. See the current New England GreenhouseFloricultural Crop Pest Management and GrowthRegulation Guide for specific pesticide materials.

Aphids have many natural enemies, includingladybird beetles, lacewings, flower flies, parasitic waspssuch as Aphidius matricariae, and the predaceous midgeAphidoletes aphidomyza. Several of these are availablefrom commercial insectaries (see Appendix B).

Aphidius and Aphidoletes should be used incombination; Aphidoletes provides rapid control of largepopulations and Aphidius provides control of lowpopulations.

In addition, aphids are attacked by certain fungaldiseases specific to insects. Researchers are investigatingthe use of these natural enemies for aphid control ongreenhouse crops.

MITES

Two-spotted spider mites

The most commonly encountered greenhouse miteis the two-spotted spider mite. Mites are close relativesof insects and are sometimes referred to as red spiders,although they are not spiders at all. They are minutearthropods, and their largest life stage, the adult female,is less than a millimeter in size. The body of the adultfemale and of most immature stages is oval shaped,usually light yellow to green, with two large dark greenspots on either side. All life stages have eight legs except

for the larval stage, which has six.Spider mites attack virtually every florist crop,

including most species of foliage plants. They causesevere chlorosis in attacked plants because the mites feedby “stabbing” cells with their piercing mouthparts andsucking out the juice. Spider mites remove chlorophyllfrom plant cells and reduce photosynthesis. Removal ofchlorophyll produces the characteristic stippling ormottling of foliage and sometimes causes leaf drop.

Two-spotted spider mite, Tetranychus urticae.

When mite populations are low, they prefer to at-tack the lower surfaces of leaves. As the population in-creases they tend to move upward. In severe infesta-tions, plants may be covered with the characteristic web-bing of the mites, which is why they are referred to asspider mites.

Females lay up to 12 eggs per day on the undersideof leaves, usually in the fine webbing that the mitesconstantly produce. One female is capable of laying morethan 100 eggs during her lifetime. The eggs hatch in asfew as 3 days, depending on temperature, and the newlyhatched mites (called larvae) immediately begin feeding.After as few as 5 days, the mites pass through twonymphal stages and become adults. Females begin layingeggs within 1 to 3 days. Mating is not required.

Survival, development time, and reproduction aregreatly influenced by environmental factors such astemperature, humidity, and host plant. Temperature isthe most important factor. The development from eggto adult takes about 7 days at 81°F and about 20 days at64°F. Rapid population increase can occur astemperatures warm. Spider mites do best under hot, dryconditions and develop faster on water-stressed plants.

Pesticide resistance can be a common problem inspider mite control. Unfortunately, many strains of mitesexist, and many of these strains are resistant to certainacaricides (miticides). Currently there are a variety ofeffective acaricides, but unless these chemicals are usedcarefully and sparingly, it is only a matter of time beforeresistant strains evolve.

68

Weeds are an alternative food for spider mites andshould be eliminated. A weekly routine plant inspectionprogram is the best method for spider mite management.Plants should be scouted carefully for the first signs ofleaf stippling caused by spider mites. Choose plantsrandomly from each bench and inspect the lower leafsurfaces for mites. Particular attention should be givento areas of the greenhouse where mites may be spreadon the clothing of workers, such as along walkways andnear entrances. Attention should also be focused on plantspecies or varieties that are particularly susceptible tomite infestations and in areas of the greenhouse that havea history of mite problems.

Efficient and regular scouting can lead to earlydetection. Application costs can be reduced and largearea sprays can be avoided by spot spraying earlyinfestations.

Infested plants should be marked and reinspectedwith a hand lens several days after treatment to evaluatethe degree of control. Some miticides are not effectiveagainst mite eggs and repeat applications may be neededafter 5 to 7 days. Thorough coverage of upper and lowerleaf surfaces is critical for effective mite control. See thecurrent New England Greenhouse Floricultural Crop PestManagement and Growth Regulation Guide for specificpesticide materials.

Care should be taken when using insecticides in areaswhere spider mites are present. Research indicates thatcarbaryl and certain pyrethroids and organophosphatesmay actually increase mite populations by increasingnitrogen levels in plant leaves.

Commercially available predatory mites can beeffective alternatives to chemical treatment. Multiplereleases are usually required and heavily infested areasmay require a miticide treatment before predatory release.Predatory mite species include Amblyseius californicus,A. cucumeris, A. fallacis and Phytoseiulus persimilis.See Appendix B for more information.

Cyclamen mites

These microscopic pests are rarely seen by growers.The damage they cause, however, can be extensive. Thetiny mites hide in protected locations on the host plant,usually the buds and flowers. They are serious pests ofa number of flowering and foliage plants, includingcyclamen, African violet, ivy, snapdragon,chrysanthemum, begonia, and fittonia.

Cyclamen mites feed by piercing plant cells. It ispossible that cyclamen mites also damage plants byinjecting a toxin as they feed. The foliage expanding frominfested buds often becomes so curled and distorted that

plants are unmarketable.Unfortunately, their extremely small size makes it

difficult to detect an infestation of cyclamen mites beforedamage occurs. The injury they cause can resemble thripsfeeding damage, phytotoxicity, or physiological disorders.To avoid inappropriate control actions, plants that displaycurled distorted leaves should be carefully examined forthe presence of cyclamen mites using a hand lens or,preferably, a dissecting microscope.

Cyclamen mite, Phytonemus pallidus.

Female cyclamen mites lay 1 to 3 eggs each day anda total of 12 to 16 during their lifetime. Mating is notrequired for egg production; unfertilized eggs developinto males and fertilized eggs develop into females. Theeggs require 4 days to hatch at 70° F. The life cycledepends on temperature but is usually completed in 1 to3 weeks.

Cyclamen mites may spread by air currents, by directcontact between plants, or by workers who handleinfested plants. Chemical control is difficult because themites are difficult to reach with acaricides. It is usuallynecessary to make two or three spray applications toachieve control. See the current New EnglandGreenhouse Floricultural Crop Pest Management andGrowth Regulation Guide for specific pesticide materials.

When feasible, the mites can be satisfactorilycontrolled by immersing infested plants in water heatedto 110° F for 30 minutes. This is obviously not a practicalmeans of control when large numbers of plants areinvolved, but it is a very useful way to eliminate isolatedinfestations. Certain species of predaceous mites mayalso be useful for biological control.

69

WHITEFLIES

Two species of whiteflies infest greenhouse plants.These are the greenhouse whitefly (GHWF, Trialeurodesvaporariorum) and the silverleaf whitefly (SWF, Bemisiaargentifolii). SWF is becoming more common onpoinsettias. It is not uncommon to find both whiteflyspecies in the same greenhouse. SWF can be a verydamaging greenhouse pest because of its broad hostrange, its resistance to insecticides, and its potential tovector a variety of plant virus diseases. Any growerexperiencing unusual difficulty in controlling GHWF mayunknowingly be battling this newer whitefly pest.

A hand lens or other magnifying device should beused to tell the difference between these two whiteflies.Observe the pupal stage to differentiate between them.The “skin,” or “pupal case,” left behind after the adultemerges can also be used for identification. No other lifestages, except perhaps the adult, can be used for reliableidentification.

The pupal stages of both species are commonlyfound on the underside of leaves. The pupal case ofGHWF has parallel sides which are perpendicular to theleaf surface, giving the pupa a disk-shaped or cake-shapedappearance. SWF pupae appear more rounded, or dome-shaped, with no parallel sides. The GHWF pupae havea tiny fringe of setae around the rim of the pupa in topview. The SWF pupae have no fringe or setae aroundthe edges. Both species may have several pairs of longerfilaments arising from the top of the pupa. Usually thesefilaments are larger and more obvious on GHWF thanon SWF, but this characteristic can vary depending onthe host plant on which the insect developed. Therefore,the size of these filaments is not a reliable trait and shouldnot be used for identification. These differences are notdifficult to see with a 10X hand lens.

The adult GHWF is larger than the SWF and holdsits wings fairly flat over its abdomen in a plane almostparallel to the leaf surface. The SWF adult is slightlymore yellow in color and holds its wings roof-like againstits abdomen, at approximately a 45-degree angle withthe leaf surface. Wings are held tightly against the body.Although the appearance of the adults can be used todifferentiate between these two species, the pupal stagemust be used for confirmation.

Whitefly adults are small, white, fly-like insects. Theyare considered pests primarily because their presencedetracts from the aesthetic value of greenhouseornamentals. Feeding damage can cause plants to becomechlorotic. Their honeydew excretions make leaves sticky

and shiny and serves as a food source for a grayishblack sooty mold fungus, which interferes withphotosynthesis and detracts from the plant’s appearance.

Based on our present knowledge, the life cycles ofGHWF and SWF on poinsettia are generally similar. Eggsare deposited on the underside of leaves, sometimes in acrescent-shaped pattern. The spindle-shaped eggs arewhite when first laid and turn gray withtime. At temperatures between 65 and 75°F, the eggshatch in about 10 days for GHWF and 12 days for SWF.The tiny first nymphal stage, or crawler, hatches fromthe egg, crawls a few millimeters, and settles down tofeed. It does not move from this spot until emerging asan adult. GHWF and SWF pass through three morenymphal stages before adult emergence. The pupal stagelasts 4 days for both species. The pupal stage isrecognized by the red eye spots visible through the pupalcase.

The entire life cycle of GHWF and SWF takes anaverage of 32 and 39 days, respectively, to develop fromegg to adult on poinsettia. About 14 to 16 days of thistime are spent as eggs or pupae which are tolerant ofmost labelled insecticides.

An adult female can begin laying eggs from 1 to 4days after emergence. Mating is not necessary for eggproduction. A female may lay up to 200 eggs and live upto 1 month, but this depends greatly on the whiteflyspecies and environmental conditions, such as

Adult whiteflies on citrus.

70

Greenhouse whitefly, Trialeurodes vaporariorum.A, Egg. B-E, Nymphs. F, Pupa. G, Adult.

Silverleaf whitefly, Bemisia argentifolii.A, Egg. B-E, Nymphs. F, Pupa. G, Adult.

A

BC

DE

G

A

B

C

D

G

FF

E

temperature and host plant.Infestations may build rapidly if not controlled early,

and overlapping life stages are common. All whitefly lifestages are found almost exclusively on the lower surface ofleaves. Adult whiteflies are capable of flying at least 50 feetover a 24 hour period, although most seem to remain within10 feet of their emergence site.

The following are guidelines for the management ofwhiteflies:

Start the season with a clean greenhouse. If possible,eliminate all plants in the greenhouse, including weeds,for at least one week. All immature whiteflies will beremoved when plants and weeds are removed, andany adults will die due to lack of food. If completeplant removal is not possible, eliminate all weeds andthoroughly inspect other plants in the greenhouse forthe presence of immature or adult whiteflies. Considerdiscarding infested plants, or move them to anothergreenhouse for treatment.Prevent whiteflies from being introduced into thegreenhouse. Examine cuttings and new stock on arrivalfor the presence of immature and adult whiteflies beforeadding them to the existing crop. Do not assume thatplants are uninfested just because adult whiteflies arenot seen; eggs and other immature stages may be

present. Inspect the underside of leaves for thepresence of any life stage.Learn to recognize the first signs of a whiteflyinfestation. Train all greenhouse workers torecognize the early signs of an infestation,including the presence of immature stages on theunderside of leaves. Spot check the leafundersurface of several plants throughout thegreenhouse weekly. Place yellow sticky cards justabove the canopy and check them weekly tomonitor whitefly adult populations. Use one cardfor every 1000 sq ft. Record whitefly numberson the cards to monitor adult whitefly levels.Prevent the spread of whiteflies from onegreenhouse range to another. Avoid wearingyellow, a color highly attractive to whiteflies.Consider using screens or other barriers to excludeor confine the pests.Learn which plants or cultivars are moresusceptible to whitefly infestations. Group theseplants together and monitor them carefully.Treat plants when the first signs of infestationare noticed; do not wait until clouds of adults canbe flushed out of the plants. Roguing infestedplants may delay the start of insecticidal sprays.To estimate the degree of control after an

71

insecticide treatment, prior to application locateseveral infested leaves, mark them with flagging tapeor by another means, note the approximate numberof immature whiteflies, and apply the insecticide.Several days after application, reevaluate the numberof whiteflies on the marked leaves.Although chemical control should be viewed as only

one aspect of a total whitefly management program, itpresently is an extremely important aspect. The eggsand most of the last nymphal stages of both the GHWFand the SWF are tolerant to most labelled insecticides;the adult and young immature stages are moresusceptible. If an infestation contains all life stages,repeated insecticide applications are necessary to killindividuals that progress from the resistant stages to aninsecticide-susceptible stage.

It is not always wise to judge the performance of aninsecticide merely by the presence or absence of adultwhiteflies after a single application. For example, withsome insecticides all adult whiteflies could be killed onthe day of the application, but individuals in the lastnymphal stage would remain unaffected. A day or twolater adults emerge from this unaffected stage, and thegrower may wrongly assume that the insecticide wasnot effective. Several applications may be necessary foran accurate evaluation of a new insecticide.

Spray intervals depend, in part, on the residualeffectiveness of each insecticide used, the length of timethe whiteflies stay in an insecticide-tolerant life stage,and the size of the population. With a low to moderateinfestation, non-systemic insecticides (foliar sprays andaerosols) should be applied every 5 to 7 days throughthe duration of one whitefly generation (21 to 30 days);aerosols should be applied somewhat more frequently.

Whiteflies occur on the underside of leaves, and mostof the life stages are stationary and do not crawl overtreated leaf surfaces. If sprays are directed against theimmature stages, the insecticide must be applied so thatit comes in contact with the insect. Thorough coverageand good canopy penetration are therefore criticallyimportant. Respacing plants may increase canopypenetration.

Registered systemic insecticides can be veryeffective, as long as a sufficient amount is translocatedto sites at which whiteflies are feeding. Systemics areusually most effective when applied early in the crop’sdevelopment. If necessary, applications should berepeated every 3 to 4 weeks.

A heavy whitefly infestation may call for systemicinsecticide applications twice a week when this ispermitted on the label. Such a heavy use of insecticidemay damage plants and should therefore be reserved

only for extremely severe infestations. In some instancesheavily infested plants should be thrown out. A growerwho experiences a major whitefly problem shouldconsider the circumstances that led to the problem toavoid repeating past mistakes.

The choice of which insecticide(s) to use dependson several factors. Always read and follow all labeldirections. An insecticide’s phytotoxic potential maychange with the crop or plant cultivar and with differentenvironmental conditions. Also, whitefly populations candevelop different levels of resistance to differentchemicals from one greenhouse to another. A giveninsecticide may therefore provide effective control in onegreenhouse but not in another. See the current NewEngland Greenhouse Floricultural Crop Pest Managementand Growth Regulation Guide for specific pesticidematerials.

In summary, for effective whitefly control, maximizenonchemical control efforts and avoid unnecessarysprays. Treat at the first sign of an infestation andmaintain control during early crop development to avoidproblems later. When nonsystemic insecticides are usedagainst a low or moderate infestation, apply every 5 to 7days for the duration of one pest life cycle. To minimizepesticide resistance problems, avoid unnecessary sprays,avoid using insecticide tank mixes whenever possible,and rotate insecticides from different chemical classesevery pest generation about every 1½ to 2 months.Monitor population levels weekly with yellow sticky cardsand with crop inspections.

Biological control may be difficult for whiteflyinfestations. The parasitic wasp Encarsia formosa is noteffective against silverleaf whitefly. A more efficientparasite, Eretmocerus californicus is difficult to establish.The coccinellid predator, Delphastus pusillus requireshigh prey density. For more information, see Appendix B.

SCALES AND MEALYBUGS

Scale insects and mealybugs are often difficult tocontrol for several reasons. First, they are not easilydetected because they do not always resemble an insect;often they are mistaken for plant parts. It is easy forthem to go unnoticed, particularly at the onset of aninfestation when their numbers are low. Second, a waxysecretion covers their bodies and protects them. It isdifficult for insecticides to effectively penetrate this waxbarrier. Third, they often occur on the underside ofleaves, in leaf axils, or on roots. These cryptic habitatsmake detection difficult and provide protection from

72

sprays. Fourth, they can rapidly develop overlappinggenerations so that all life stages are present at a giventime. Certain stages are not susceptible to insecticides,so repeated sprays are usually required at regular intervalsto contact all the susceptible stages in the population.

Mealybugs and scales are related to aphids andwhiteflies. They are all classed in the insect orderHomoptera. These soft-bodied insects feed with stylet-like mouthparts. They insert their stylet into plant tissuesand suck plant juices.

Early detection is very important for effectivecontrol. Greenhouse workers should be trained torecognize these pests and the early symptoms of damage.As soon as an infestation is detected, it is best to isolatethe plant(s) if possible to prevent spreading the problemto uninfested plants. It may even be wise to discard abadly infested plant(s) rather than spend time and moneyon control attempts while risking further spread of theinfestation.

If contact insecticides are used, they should beapplied during the crawler stage of scales and mealybugs.Repeated applications are therefore necessary to contactthe susceptible stages as they are produced. Sprayintervals will depend on the residual effectiveness of theinsecticide used, which may vary from 0 to 3 weeks.The inclusion of a spreader-sticker can improve coverage,penetration, and residual activity, although the risk ofphytotoxicity may be increased. Good coverage isimportant for contact insecticides. Insecticidal oils andsoaps can sometimes be effective, killing more life stagesof these pests than many contact insecticides, but theyprovide no residual control. Again, thorough coverage iscritical.

Systemic insecticides may kill actively feeding stagesof scales and mealybugs, assuming adequate amountsof insecticide are translocated to the feeding site. Systemicswill not kill the egg stage. An additional application maybe necessary after 3 to 4 weeks if the residual activity ofthe systemic is inadequate after this time period in orderto kill newly hatched insects. Fumigant insecticideformulations can be effective against mealybugs andshould be applied at 10 to 14 day intervals. See thecurrent New England Greenhouse Floricultural Crop PestManagement and Growth Regulation Guide for specificpesticide materials.

The potential for biological control of certainmealybug and scale pests, particularly in interiorplantscape settings, continues to improve. Parasitoids andpredators of these pests are commercially available.Information regarding the use of these natural enemiesand integrated control of these pests can be obtainedfrom commercial insectaries (see Appendix B).

Armored scales

Florida red scale, Chrysomphalus aonidum.

Armored scales are usually smaller than soft scalesand their shapes vary between species, from a circularshape to an irregular shape resembling an oyster shell.Color may vary with life stage, sex, and species. Colorranges from shades of white to gray, red, brown, orgreen. These insects secrete a hard waxy shield overtheir bodies. This shield may separate from the body ofarmored scales, but it is inseparable from the body ofsoft scales.

Some common armored scale pests of greenhousesand interior plantscapes include oleander scale,Boisduval’s scale, San Jose scale, Florida red scale, fernscale, greedy scale, purple scale, and cactus scale. Contactyour local county Cooperative Extension office to assistyou with identification of the common armored scales.

It is very important to detect the early stages of anarmored scale infestation. Besides detecting the actualinsects on the plants, knowing the symptoms of aninfestation on the plant is very important. Armored scalescan produce either yellow or brown spots or streaks onthe leaves. They may also cause general yellowing ofthe foliage, poor growth, and encrustations of both stemsand leaves. In very large populations they can causetwig dieback and even plant death. Unlike mealybugsand soft scales, armored scales do not produce honeydew.

Aspects of the biology and life cycle of armoredscales can vary significantly between species; thefollowing is a general description. The eggs are producednext to the female underneath her scale cover or shield.Some species give birth to living young. Females canproduce 20 to 400 eggs. These hatch into crawlers, astage that is susceptible to insecticides. The naturalmortality of crawlers is high. They move a short distancefrom where they were hatched, find a suitable place tosettle down and feed, and do not move again for theremainder of their lives. Females pass through twonymphal stages prior to adulthood. Males pass throughtwo additional short pupal or resting stages. The tinywinged males do not live long. Females begin to produce

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females is roughly 40 to 80 days, depending, again, onfactors such as host plant, temperature, and species. Alllife stages may be present at any one time.

Mealybugs

Mealybugs are small (1 to 8 mm long), soft bodiedinsects covered not by a hardened cover or shield butwith a layer of white cottony wax. They can be foundinfesting all parts of a plant, including the roots. Theirbody shape is an elongated oval. Some produce shortspinelike filaments along the margins of their bodies andposterior filaments may be quite long. Mealybug pestsof greenhouse crops include the citrus mealybug, theobscure mealybug, and the longtailed mealybug.

Mealybug infestations can cause leaf distortion,particularly on new growth. As they feed, some speciesinject a toxin, which can produce necrotic spots, generalyellowing, or leaf drop. Mealybugs produce honeydewwhich can support the growth of sooty mold. Theirproduction of a white cottony wax and their verypresence on leaf axils or underside of leaves detract fromthe appearance of the plant. As with soft scales, ants areattracted to honeydew, and the presence of ants maysignal a mealybug infestation.

Life cycles vary tremendously among differentspecies but may be generalized as follows: Femalesproduce from 300 to 600 eggs, usually in a white cottonycovering called the ovisac. Some species give birth tolive young. The eggs mature in the ovisac forapproximately 2 weeks, then hatch into crawlers. Thecrawlers are the life stage most susceptible to insecticides.Although slow moving, all subsequent life stages ofmealybugs are mobile, not stationary like scale insectsand whiteflies. It is therefore easy for this pest to movefrom leaf to leaf or plant to plant and spread an infestationover many plants. Males are tiny, winged insects. Lifecycles last from 30 to 70 days.

eggs after mating. The entire life cycle can take 60 to120 days to complete, depending upon temperature andspecies. Several generations may occur during the year,and all life stages may be present at any one time.

Soft scales

Black scale, Saissetia oleae.

Soft scales can be fairly large (2 to 5 mm) and usuallyhave a circular or oval shape. They are often shades ofgray or brown, but some species appear black. The shieldcannot be detached from soft scales. Common speciesinclude black scale, brown soft scale, hemispherical scale,and Niger scale.

By feeding on young tissue, soft scales causedistorted foliage, yellow leaves, and, in large populations,dieback of twigs and branches. Soft scales (andmealybugs) produce a sugary excrement called honeydew,which can fall onto leaves and make them shiny andsticky. Honeydew can support the growth of unsightlysooty mold. The presence of honeydew and sooty moldis a good indication of an infestation. Because ants areattracted to honeydew, their presence on the plants mayalso signal an infestation.

The general life cycle of soft scales is fairly similarto that of armored scales. Eggs or living young areproduced beneath the female’s body. Females canproduce more than 1,000 eggs. Crawlers hatch after 1to 3 weeks, crawl over the leaf and stem for severaldays eventually finding a suitable feeding site at whichthey remain through adulthood. Like armored scales,the crawler stage is the most sensitive to insecticides.Females pass through three or four immature stagesbefore adulthood; males pass through four immaturestages. Adult males emerge as tiny, delicate, wingedinsects which live only a few days. The life cycle of

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Longtailed mealybug, Pseudococcus longispinus.

THRIPS

Several species of thrips can infest greenhouse floralcrops, but the most severe pest in recent years has beenthe western flower thrips (WFT), Frankliniellaoccidentalis. This discussion will be confined to WFT.

WFT, previously found primarily west of the RockyMountains, are now common in greenhouses throughoutthe world. They have probably been spread on infestedcuttings. WFT can be found year-round insidegreenhouses in the Northeast as long as plants (includingweeds) are available for food and temperatures arefavorable. It is not known whether WFT can overwinteroutdoors in this climate.

Some people identify WFT as any thrips that cannot be controlled by insecticides and there may be sometruth in this method of identification.

Thrips are tiny insects. Adults are 1 to 2 mm inlength and have narrow bodies with fringed wings. Colorscan vary from straw yellow to brown. It is not possibleto accurately identify which thrips species is infesting acrop in the greenhouse, even with a hand lens. Minordifferences in morphological structure are used to tellone species from another. Therefore, adult thrips mustbe inspected under a compound microscope to accuratelydetermine the species. Contact your local countyCooperative Extension office to assist you withidentification

WFT feed by piercing plant cells and sucking outthe cell fluids. The collapse of plant cells caused bythrips feeding can result in deformed plant growth and

FE

CD

A

B

Western flower thrips, Frankliniella occidentalis.A, Egg. B-C, Larvae. D, Prepupa. E, Pupa.

F, Adult.

flowers. Damage on the surface of expanded leaves orpetals appears as small silvery patches which displaytiny greenish black fecal specks left by the thrips. WFTdamage the appearance of African violets by spreadingpollen over the flowers.

One of the most serious threats of a WFT infes-tation is the pest’s ability to spread tomato spotted wiltvirus. There is no cure for this disease, and one WFTadult can infect a plant after feeding on it for only 30minutes. Because both the virus and the thrips havesuch a wide range of plant hosts (including weeds), itmay be difficult to eradicate the virus once it is presentin a greenhouse.

Control of western flower thrips is extremely difficultdue to several biological characteristics of this species.Eggs are inserted into plant tissue and are thus protectedfrom insecticides. The egg stage lasts from two and ahalf to four days. The eggs hatch into larvae, whichusually remain protected inside flower buds or terminalfoliage.

The insect passes through two larval stages, both ofwhich feed in these protected areas. The first larval stagelasts 1 to 2 days, the second larval stage lasts 2 to 4days. Toward the end of the second larval stage, theinsect stops feeding and moves down into the soil or leaflitter to pupate.

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The insect passes through a prepupal and pupal stage,during which no feeding and little movement occurs.The prepupal stage lasts 1 to 2 days, and the pupal stagelasts 1 to 3 days. While in the pupal stage in the soil, theinsect is not exposed to insecticides directed at the foliage.

The adults can survive from 13 to 75 days and lay40 to 250 eggs (depending on temperature and hostplant). They are also primarily found feeding in protectedareas of the plant such as flowers and terminal buds.

The pest’s rapid development time (egg to adult in7.5 to 13 days at fluctuating temperatures), rapidreproductive rate, and its presence in protected parts ofthe plant can allow an undetected infestation to quicklybecome a major problem. They fly readily, although theyare not strong fliers, and may be carried on wind currentsor clothing to greenhouses near an infestation. They canfly from a sprayed to an unsprayed area, or they canmove into or out of a greenhouse through doors or vents.Effective chemical control is complicated by insecticideresistance. Resistance to certain organophosphate,carbamate, and synthetic pyrethroid insecticides has beendocumented in certain populations of WFT.

Weed control is critical to thrips control. Weeds,whether inside or outside the greenhouse, are a refugefor thrips (as well as tomato spotted wilt virus). Weedsshould be eliminated inside the greenhouse and from thearea immediately outside the greenhouse as far as isreasonably feasible, particularly near vents and doors.Weed barrier covered with coarse gravel can be used tomaintain a weed-free zone around a greenhouse.

Early detection of a thrips infestation is criticalbecause the symptoms of their feeding are often notnoticed until after the damage has occurred. Also, aninfestation is easier to control when it is small. Yellowsticky cards provide an easy way to detect the onset ofan infestation. To monitor the movement of thrips, placeyellow cards just above the crop canopy, about one per2,000 square feet, as well as near doors and vents andover thrips-sensitive cultivars. Recent research has shownthat blue sticky cards catch more thrips than yellow ones,but because other insect pests are also attracted to yellowcards, it may be more efficient to use yellow cards forgeneral pest monitoring.

The number of thrips per card should be recordedand graphed weekly to monitor population levels andaid in control decisions. Although it is more efficient touse sticky cards to detect and monitor thrips, flowerscan also be checked for thrips by tapping a blossomover a sheet of paper. Yellow and white flowers seem tobe particularly attractive to thrips. Useful trap plantsinclude the following petunia varieties: Summer Madness,Super Blue Magic and Calypso.

Although effective thrips management can bedifficult, adequate control can be achieved by acombination of physical, cultural, and chemical measures.Prevention is the first step in a management program. Itis easier to prevent an infestation than to manage anestablished one. Growers should avoid purchasing plantmaterial infested with thrips. Research has shown thatthe use of fine screens (200 to 400 mesh) or barriersover vents can help prevent the movement of thrips intoa greenhouse. Researchers are also examining the use ofmaterials such as Visqueen to cover plants on greenhousebenches. Greenhouse workers should avoid wearingyellow or blue so that thrips are less likely to be spreadon workers’ clothing.

Adequate chemical control depends on theinsecticide selected, the number and frequency ofapplications, the application method, the spray particlesize, and pesticide rotation.

The addition of sugar to the spray mix may enhancethrips control The sugar acts as a bait and draws thripsout onto the leaf surface. Unfortunately, results havebeen mixed. Sugar can also cause the development ofsooty mold.. Add sugar in the ratio of 1 pound to 100gallons of warm water.

Several insecticide applications should be made at 5day intervals to reduce a thrips infestation significantly.None of the recommended insecticides are effective withonly one application. Research has shown that 5 dayapplication intervals are more effective than 7 dayintervals.

Ideally, insecticides should be applied with equipmentthat produces very small spray particles (less than 100microns). Spray particles of this size are best becausethey penetrate deep into the protected areas of the plantwhere the thrips are found and provide the most efficientuse of insecticide if coverage is thorough. Smoke oraerosol fog formulations of effective insecticides can alsoimprove control.

Rotating the use of insecticides from differentchemical classes can be an effective way to delay theproblem of insecticide resistance. It is best, however, touse an effective insecticide for more than one generationof a pest before rotating to another insecticide. Giventhe duration of the life cycle of WFT, an effectiveinsecticide should be used for 2 to 3 weeks beforeswitching to an insecticide from another class ofchemicals. See the current New England GreenhouseFloricultural Crop Pest Management and GrowthRegulation Guide for specific pesticide materials.

Research on biological control of WFT is beingconducted in several laboratories worldwide. Currentemphasis is on commercially available species of the

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predaceous mites Amblyseius cucumeris and A. barkeri,a parasitic wasp, Thripobius semiluteus, and severalspecies of minute pirate bugs in the genus Orius.Research with two fungal pathogens, Metarhiziumanisopliae and Beauveria bassiana, may also lead tocommercial formulations. See Appendix B for moreinformation on biological control.

LEAFMINERS

Although a number of species of leafminers canattack florist crops, the most common are flies of thefamily Agromyzidae, and the most common and severepest species is Liriomyza trifolii. These tiny flies (2mm)

A common leafminer, Liriomyza trifolii.

are yellow and black, resemble small fruit flies, and arestrong fliers.

Females make small punctures on upper leaf surfaceswith their ovipositors. Females and males feed on exudingplant juices from these punctures, and, in some of them,females will lay a single egg. The punctures turn whitewith time and give leaves a speckled appearance. Onhatching, the larvae slash open surrounding cells usingtheir sickle-like mouth hooks. As the cells are ruptured,the larvae move forward to destroy more cells. Continuingin this fashion, they leave winding trails, or mines, in theleaf. The mines increase in length and width as the insectsgrow. The appearance of the larval mines reduces theaesthetic value of the plant.

The duration of the life cycle depends on temperatureand host plant. In general, eggs hatch in 4 or 5 days.The larvae feed within the leaf for 4 to 6 days, molting

twice. Third instar larvae usually chew a small slit in thelower leaf surface and drop to the soil or onto lowerleaves to pupate. The pupal stage can last from 35 daysat 58° F to 9 days at 80° F.

The best initial defense against leafminers is to refuseto accept infested cuttings. Incoming plant material shouldbe inspected for leaf stipples and active mines and heldfor several days to see if mines develop from leaf stipples.Yellow sticky cards can be used to detect adult activityand to monitor population levels.

Contact sprays to control adults should be repeatedat 3 to 4 day intervals to kill those adults that continue toemerge from puparia during the 10 to 14 days followinginitial treatment. Systemic insecticides can be veryeffective against the larvae. See the current NewEngland Greenhouse Floricultural Crop Pest Managementand Growth Regulation Guide for specific pesticidematerials.

Recent work on the biological control of leafminershas been successful on certain flower crops. Releases ofparasitic wasps as well as nematodes that only attackinsects have been successfully used under certainconditions.

CATERPILLARS

Caterpillars or “worms” are the immature or larvalforms of butterflies and moths. Some of these insectsare exceptionally large, and others, when young, arebarely visible without magnification. Included within thisdiverse group are armyworms, cutworms, leaftiers,leafrollers, and loopers.

These insects cause damage only as larvae; the adultseither do not feed or feed only on nectar. The larvae,however, more than compensate for the adults’innocuous behavior. With their strong jaws, caterpillarsconsume large amounts of foliage, tender stems, andeven whole flowers. When their feeding does not causethe total loss of small seedlings, they often leave ragged,unmarketable plants. The preference of some species,such as the beet armyworm, for tender bud and shoottissue can produce continued pruning of a crop such aschrysanthemums and ruin its value for cut flowers.

Many of these pests cannot successfully overwinterin Maine. Greenhouse infestations occur only wheninfested stock is brought in. Other caterpillars do notusually persist in the greenhouse, but adults can beattracted by lights and fly in from outdoors to lay theireggs. This commonly occurs with cabbage loopers.

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Because there are so many caterpillar species, it isdifficult to generalize about their life cycles. Some specieslay eggs on the plants; others lay eggs on the soil. Somecaterpillars prefer to hide in the soil during daylight andemerge to feed only at night; others remain on the plantsat all times; and still others fold leaves around themselvesfor protection. Some species change to adults (pupate)in soil; others pupate on the plant. The list of differencesis long and proper identification of the pests beforebeginning a control program is necessary. YourCooperative Extension office can assist you and adviseyou of the best control program.

A careful and routine scouting program is importantfor optimum pest control. Plants should be inspected forsigns of leaf feeding. Screens placed over air inlets canexclude adult moths. Some caterpillars can be controlledby the biological control organism Bacillus thuringiensis(Bt) var. kurstaki. This bacterium is sold commerciallyunder several trade names. Bt is an excellent first choicefor controlling caterpillars because it is practically nontoxicto humans, insects or any other animal other thancaterpillars, it does not affect beneficial insects, and itdoes not have adverse effects on the environment.

FUNGUS GNATS AND SHORE FLIES

Fungus gnat adults are small, slender black or darkbrown flies about 1/8 inch long. The two wings aredelicate and either smoky or clear. The many-segmentedantennae are longer than the head. Legs are long andthin. Adults are weak flyers and may be found flying orrunning over soil surfaces or leaves.

The larva, which is the life stage that actually damagesgreenhouse plants, is legless and wormlike, with a whitebody and a distinct black head capsule. It is about ¼inch long during its final stages of development.

The fungus gnat may be confused with another smalldark-bodied fly called the shore fly. Considered harmless,shore flies do not affect greenhouse crops in any way.They feed on algae growing on the soil surface and arefavored by the same wet conditions that are attractive tofungus gnats. With both insects, large numbers of adultsmay be a nuisance.

Shore flies have more robust bodies than fungusgnats and their antennae are very short. Their mostdistinguishing characteristic, however, is the presence offive light-colored spots on each of their dark wings. Shoreflies are also stronger, faster fliers than fungus gnats. Inthe larval stage, shore flies can be distinguished by theopaqueness of the body and the absence of a headcapsule. Shore flies feed by means of a pair of smallmouth hooks. They have a characteristic forked air tubeat the posterior end of the body.

Fungus gnats are associated with the use of artificialsoil mixes high in organic matter. These flies are attractedto damp locations where fungi flourish. Fungi are a majorpart of their diet, but the larvae do not limit their feedingto fungi. They are general feeders and can injure a numberof flower crops grown in the greenhouse.

Common fungus gnat, Lycoriella sp. or Bradysia sp.

Fungus gnats can be especially destructive toseedlings and young plants as they are becomingestablished. Larvae may attack the roots of growingplants, resulting in retarded plant development. Underthe stress of water deficiency, foliage may wilt. Leafyellowing and leaf drop may result. Plant parts (such asstems) below the surface of the soil may also be invaded.Tunneling of the larvae may cause collapse of the stem.The larvae also may introduce bacterial or fungalpathogens as secondary invaders.

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To monitor adults, sticky cards should be placedhorizontally, just above pot level. To monitor larvae,place a cube of potato tuber in direct contact with thesurface of the potting mix; larvae will migrate upwardinto the tuber. Inspect tubers frequently.

Chemical applications can be aimed at the larvae orthe adults, but the best long-term control targets theimmature stages. Insecticidal drenches or soil surfacesprays can be effective. Certain insecticides may notaffect eggs or pupae, and repeated applications may benecessary before control is achieved. Also, if chemicalapplications are directed only against the larval stages, itmay take some time before the number of adults isreduced. Adults can be effectively controlled with labeledaerosols or sprays. See the current New EnglandGreenhouse Floricultural Crop Pest Management andGrowth Regulation Guide for specific pesticide materials.

NEMATODES

Foliar nematodes

Leaf, or foliar, nematodes cause deformity of youngplant growth, leaf spots, and defoliation. Spots are firstvisible on the lower leaf surface as yellowish or brownishareas, which eventually turn almost black. Lesions aresmall at first, but, with favorable temperature andmoisture, they may spread until much of the leaf isdestroyed. Unlike other nematodes, foliar nematodes donot persist in the soil in the absence of living host-croptissues.

On chrysanthemum plants, the leaf veins retard thespread of the nematodes through the leaf, causing V-shaped or angular lesions. Infection begins on the lowerleaves and progresses upwards. On Peperomia, gloxinia,African violet, and Elatior begonias, the lesions are lessdefinite in outline and infection may occur on any leaf.

Foliar nematodes can be effectively controlled byfoliar or soil applications of labelled pesticides. See thecurrent New England Greenhouse Floricultural Crop PestManagement and Growth Regulation Guide for specificpesticide materials.

Root-knot nematodes

Nematode problems affecting plant root systems arequite rare, except in cases where soil is used as acomponent of the growing medium.

Root-knot nematodes may cause plants to appearstunted and unthrifty and to wilt on warm days. When

Poinsettia and geranium cuttings are particularlyvulnerable to fungus gnat attack after they have been“stuck” in the growing medium. Formation of calluses isimpeded or prevented, resulting in slow or poor rootinitiation.

In addition to direct injury to growing plants, fungusgnat adults or shore flies emerging from marketed pottedplants can be a nuisance to the consumer in the retailshop, garden center, home, hospital, or other location.

Mated female fungus gnats deposit 75 to 200 eggs,singly or in clusters. The creamy white eggs are laid incracks and crevices of the soil surface, and subsequentimmature stages can be found within the top 1 inch ofthe soil surface. Eggs mature in 3 to 6 days, giving riseto white, transparent or slightly translucent, legless larvae.Larvae feed and develop for about 2 weeks at 72°F.Pupation occurs in the soil. After about 4 to 7 days,adults emerge from the pupal skin. They live about 1week. The life cycle is very dependent on temperature;development time increases as temperatures decrease.Overlapping life stages are common.

Good sanitation practices, such as removingdiscarded plant material and growing media andeliminating weeds growing beneath benches or elsewherein the greenhouse, will minimize fungus gnat and shorefly problems. Care should be taken to eliminate standingpools of water on solid benches, on walks, and underbenches. Badly infested containers of plants should beremoved. Piles of plant debris should not be allowed tostand in the greenhouse. Do not over-water plants.

Fungus gnat and shore fly infestations can be detectedand monitored with yellow sticky cards. Weeklyinspections of yellow sticky cards can reveal the onsetof an infestation, and continued recording of the numberof adults per card per week can aid in evaluating theefficacy of control efforts.

Shore fly, Scatella stagnalis.

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the root system is examined, galls are generallyconspicuous and easily recognized. On some crops, root-knot nematodes may cause crop loss even when only afew galls are evident. The presence of root-knotnematodes may also increase the amount of plant injuryfrom bacterial and fungal diseases, or they may reducethe resistance of plants to these diseases. Galled plantswill not perform as well as healthy ones, but adequatemoisture and fertility may mask the difference in vigorbetween nematode-infested and healthy plants. Six kindsof root-knot nematodes are recognized in the UnitedStates today. All have been identified on greenhousecrops, although only the northern root-knot nematode,Meloidogyne hapla, survives outdoors. Thus, the otherfive kinds are shipped into the state on plant material.The host ranges and host-parasite relationships may vary,but all have essentially the same life history.

Eggs of Meloidogyne are about twice as long asthey are wide. They are usually found in a gelatinousmass about the posterior end of the female. Eggs hatchinto small, slender worms (larvae) about 1/50 inch long.The larvae migrate through the soil seeking new roots,which they enter near the tip. Once inside the root, thenematode does not change position. Stimulated by thenematode’s saliva, nearby root cells develop into giantcells, which provide nourishment to the nematode. Othercells adjacent to the nematode enlarge and increase innumber, forming the familiar gall or knot. After the giantcells are functioning, the nematode goes through threemolts before becoming an adult. A female can lay asmany as 2,000 eggs during her life, but the average isprobably 200 to 500.

The temperature of the soil is critical in thedevelopment of the nematode. It takes about 17 days at85°F for females to develop from larvae to egg-layingadults, 21 to 30 days at 76°F, and 57 days at 60°F.Females fail to reach maturity at temperatures above92°F or below 59°F.

Nematode spread within a greenhouse occurs wheninfested soil or plant debris is moved by people, water,or possibly wind. Migration of larvae through the soil islimited to a few feet per year. There is no known curefor root-knot nematodes. With continued care, infectedbed or bench plants can produce a good crop. Discardinfected plants carefully to prevent spreading thenematode. Preplanting treatments of steam or fumigantseffectively eliminate nematodes from soil, but be surethat infested crop residues are thoroughly decomposed.In general, chemical treatment will control nematodeseven after above ground symptoms are evident.

Other nematodes affecting roots

Other root-attacking nematodes can cause chlorosis,as well as stunted and unthrifty growth of above groundparts of the plant. Affected roots may be shortened,thickened, excessively branched to the point of becomingmatted, and are occasionally killed.

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1. Pesticides used in greenhouses must be labeledspecifically for greenhouse use.

________True ________False

2. Which is the most common greenhouse aphid spe-cies?

a. melon aphids Aphis gossypiib. green peach aphids Myzus persicaec. greenhouse aphid Aphis greenypii

3. Aphids are most reliably identified using colorcharacteristics.

________True ________False

4. How often must you inspect plant foliage to suc-cessfully monitor aphid populations?

a. once a weekb. once a monthc. once every two weeks

5. Blue sticky cards provide early warning of aphidsin greenhouses.

________True ________False

6. Which methods should be used to control aphidproblems?

a. eliminate weeds in or near the greenhouseb. inspection of plant material brought into grow-

ing areasc. regular scouting and monitoringd. all of these

7. Aphid resistance to pesticide applications shouldbe carefully evaluated.

________True ________False

8. Two-spotted spider mites are the most commonlyencountered mites in greenhouses.

________True ________False

9. In severe infestations, spider mites cover plantswith:

a. honeydewb. frassc. webbing

10. High temperatures (over 80°F) allow mite popu-lations to increase rapidly.

________True ________False

11. Many strains of spider mites are resistant tomiticides.

________True ________False

12. Which is a microscopic pest that causes dam-age similar to thrips?

a. spider mitesb. cyclamen mitesc. green peach aphids

13.Cyclamen mites can be controlled by immersinginfested plants into water heated to 110°F for 30minutes.

________True ________False

14. Which life stage should be used to differentiatebetween greenhouse whitefly and silverleafwhitefly?

a. nymphsb. pupaec. adults

SECTION 9 - REVIEW QUESTIONS

Greenhouse Pests

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15. Which insect(s) secrete honeydew?

a. whitefliesb. aphidsc. mealybugsd. all of these

16. Most whitefly growth stages are found on theupper sides of leaves.

________True ________False

17. Yellow sticky cards can be used to monitor forthe presence of whitefly adults.

________True ________False

18. What part of the plant should be treated withpesticides to control whiteflies?

19. Whitefly resistance to pesticides can vary fromone greenhouse to the next.

________True ________False

20. Scales and mealybugs can be hard to controlbecause:

a. they are covered by waxy secretionsb. they occur on leaf undersides, in leaf axils or on

rootsc. all life stages may be present at one timed. all of these

21. Insecticidal oils and soaps can kill all life stagesof scales and mealy bugs.

________True ________False

22. Armored scales do not produce honeydew.

________True ________False

23. Which insect produces a white cottony wax?

a. fern scaleb. brown soft scalec. Niger scaled. mealybugs

24. Which disease is spread by thrips?

a. leafspotb. tomato spotted wilt virusc. pythium

25. Thrips are hard to control because they live inprotected areas e.g., inside flower and terminalfoliage.

________True ________False

26. Weed control is critical to thrips control.

________True ________False

27. What color(s) should greenhouse workers avoidwearing to reduce the spread of thrips?

a. blueb. greenc. yellow

28. To help prevent resistance development, howlong should you apply an effective insecticide tocontrol thrips before switching to an insecticidefrom another class of chemicals?

a. 1 to 2 weeksb. 2 to 3 weeksc. 3 to 4 weeks

29. The first signs of leafminer damage may giveleaves a speckled appearance.

________True ________False

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30. The best initial defense against leafminers is toinspect incoming plant material for leaf stipplesand active mines.

________True ________False

31. Most caterpillars overwinter inside greenhousesand become a persistent problem.

________True ________False

32. Which insect attacks plant roots and may intro-duce bacterial or fungal pathogens?

a. fungus gnatsb. shore fliesc. beet armywormd. none of these

33. Shorefly larvae have a distinctive blackheadcapsule.

________True ________False

34. What can be used to monitor for fungus gnatlarvae?

35. Nematode problems are associated with the useof soil as a component in the growing medium.

________True ________False

36. There is no known cure for root-knot nematodes.

________True ________False

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SECTION 10

MANAGEMENT OFGREENHOUSE DISEASES

It is beyond the scope of this manual to deal withevery crop disease that occurs in the greenhouse. Infor-mation is given on the identification, symptoms, lifecycles, and management strategies for a few of the morecommon diseases. Your county Cooperative Extensionoffice can help you to identify these and other diseasesand recommend appropriate control measures. If youhave identified a disease and are familiar with its biologyand the available management strategies, then you areready to decide what type of control tactics (biological,cultural or chemical) to apply.

The most successful disease control programs relyon strategies that are planned before crop productionbegins. Successful growers are familiar with the mostcommon disease problems and can identify their symp-toms. They also keep informed about new developmentsin disease management.

A greenhouse management disease program beginswith crop production in a greenhouse that is as free ofpathogens as possible. Weeds and plant debris should beeliminated at the beginning and throughout the produc-tion of the crop. Incoming plant material should be in-spected for disease symptoms before placement into theproduction area. Diseased plants should be refused orisolated for pest control before placement into the pro-duction area. Whenever possible, plants should be pur-chased from reliable dealers who index their crops toensure they are not infected with specific diseases. Cul-ture indexing is performed by specialists and involvesremoving thin slices from the base of a cutting and plac-ing the slices in a nutrient medium. Cultures of nutrientmedia showing any fungus or bacterial growth are dis-carded along with the cuttings from which the slices wereremoved.

Pathogenic disease outbreaks occur in a variety ofways. Disease propagules can be carried on air currents,through the movement of contaminated potting mediaor plant material, in water droplets splashed during wa-tering, on infested pots or tools, or by insect vectorssuch as aphids, thrips, or whiteflies. Crop stress from

improper heating, ventilation or watering should beavoided because stress can make an otherwise healthyor resistant crop susceptible to disease.

A weekly routine of scouting plant material through-out all growing areas for symptoms or signs of disease(a 10x hand lens can be helpful for identification) canhelp detect problems when they are small and manage-able. Control efforts should be implemented in a timelyfashion.

This manual does not list specific chemical pesti-cides for controlling greenhouse diseases. For currentrecommendations see the latest version of the New En-gland Floricultural Crop Pest Management and GrowthRegulation Guide.

DAMPING-OFF

Damping-off occurs when seeds and seedlings are in-fected by soil-inhabiting fungi. In pre-emergence damp-ing-off, the seed is killed before it germinates, or beforethe seedling emerges from the soil. This may be misdi-agnosed as “poor seed”. Postemergence damping-offoccurs when emerged seedlings are attacked near thesoil line, or at the roots. The seedling wilts, the stemcollapses and the plant dies. Infections near the soil lineoften result in a spindly stem known as “wire stem” thatcannot support the top of the plant, causing it to topple.

Rhizoctonia and Pythium are the most commoncauses of damping-off, although Phytophthora,Fusarium, Botrytis and Sclerotinia are occasionally re-sponsible. Rhizoctonia causes pre-emergence damping-off, stem rot at the soil line, and wire stem. Pythiumgenerally infects the seed, and the tips of rootlets.

When tender young tissue is infected, the plant usu-ally dies from damping-off. Older plants may becomestunted due to infection of the fine roots, or they maydevelop small stem lesions that could cause girdling.

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tire leaf (a blight). Most spots are tan to dark brown,and may be circular, angular or irregular in shape.

The more common fungi causing leaf spots are Al-ternaria, Ascochyta, Cercospora, Gloeosporium,Helminthosporium, Phyllosticta, Ramularia, andSeptoria. Bacteria such as Pseudomonas andXanthomonas may also cause leaf spots. The spotscaused by bacteria are often sunken, water-soaked, andangular in outline. Tomato spotted wilt virus and impa-tiens necrotic spot virus can cause brown leaf spots. It isdifficult to determine the cause of leaf spots by symp-toms alone. However, proper identification is essentialto select the best control measures. See the sections onbacterial and virus diseases for a discussion of these dis-eases. Note that while a fungicide will not cure an estab-lished leaf spot, it will protect plants from new fungalinfections.

Prevention

Use disease-free propagating material.Water carefully, keep foliage and flowers as dry aspossible.Remove infected plant parts from the greenhouseand bury or remove from the greenhouse site.Provide good air circulation.

Young plants may partially rotnear the soil surface but they donot fall over. They remainstunted and eventually die.Rhizoctonia usually causes thistype of damping off.

Young plants may rot nearthe soil and fall over. EitherRhizoctonia or Pythium cancause this type of damping-off.

The root tips of young plantsare frequently invaded byPythium and the fungus usuallyprogresses up the stem,eventually killing the youngplant.

Chemical control requires using a registered productas a post-emergence soil drench to help prevent the dis-ease from spreading.

Prevention

Use pasteurized or sterilized media.Prevent any contamination of growing media.Use clean equipment.Use a porous, well-drained, seedling mix.Maintain adequate heat for germination.Do not sow seeds too densely or too deeply.Treat seeds or buy treated seeds.Avoid over watering.Avoid overhead watering if possible.Ensure pH and soluble salt levels are suitable topromote seedling growth.

LEAF SPOTS, FLOWER SPOTS ANDBLIGHTS (GENERAL)

Leaf and flower spots can be caused by fungi, bac-teria, viruses, or physiological disorders. Spots can varyin size from a pinpoint to lesions encompassing the en-

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WILT DISEASES (GENERAL)

Wilt symptoms can develop slowly or suddenly; theymay be temporary, as on hot days, or they may be per-manent. Wilt occurs when the water flow to affectedplant parts is stopped or slowed. Wilt can be caused bymoisture stress which is usually temporary, except wherewater has been withheld for long periods. Wilt can alsobe caused from soil media that is too wet which resultsin an oxygen deficient root zone. Other causes of wiltingare high soluble salt levels in the media, root rot organ-isms, and chewing insects.

There are several species of fungi and bacteria whichcause diseases whose symptoms include plant wilt. Whenplants are infected by a wilt organism, they wilt becausethe organism and/or its by-products block the water con-ducting vessels. Symptoms include the wilting of part ofa leaf, an entire leaf, one side of the plant, or the wholeplant. Affected plants may be yellow, stunted, and havediscolored vascular tissue in the stem.

The fungi most often involved in wilt diseases areFusarium oxysporum, Verticillium dahliae, and Verti-cillium alboatrum. The Verticillium fungi infect manytypes of ornamental plants, while special forms ofFusarium oxysporum infect specific host plants. For ex-ample, Fusarium oxysporum f.sp. cyclaminis infects onlycyclamen, and Fusarium oxysporum f.sp. dianthi in-fects only carnations.

Verticillium is a fungus capable of infecting a widevariety of ornamental plants. Symptoms vary with thehost. The most characteristic symptoms are one-sideddevelopment, wilting and yellowing of leaf marginsprogressing upward from the lowest leaves, lack of leafand stem lesions, and normal appearing roots. Thesesymptoms, however, can be quite different dependingon the crop. The fungus causing the disease invades thesoil and may persist there for many years. Initial infectionusually occurs through normal roots, and the fungusgrows upward through the water-conducting (xylem)tissues. Infected plants of some types (for example,chrysanthemums) are usually not killed by the fungusand, during periods of rapid vegetative growth, can appearto be without symptoms. Cuttings taken from diseasedplants without symptoms can carry the fungus internallyand introduce the disease to new areas.

Snapdragons can appear completely healthy untilblossoms develop; then the foliage can suddenly wiltcompletely. The conductive tissues of some varieties canturn brown or purple, particularly the woody stem tissues.

Verticillium wilt of chrysanthemum. The plantat left shows typical killing of lower leaves ofthe older flower stalk from the base upward,and development of a number of apparentlyhealthy basal shoots. The center plant showssimilar symptoms plus stunting. The plant atright was killed before flowering.

Verticillium wilt of strawflower. The two short,wilted plants are shown 5 weeks after artificialinfection in the greenhouse. The tall plant ishealthy.

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PreventionMinimize heat stress by shading or ventilating.Avoid high salts caused by overfeeding and/orunderwatering.Monitor the crop’s E.C. Levels.Minimize soil pathogen contamination of crops bykeeping hose ends and pots off the ground.Where possible, grow varieties that have been sel-ected for resistance to wilt diseases.Use disease free propagating material.Use sterile or pasteurized growing media

ROOT ROTS

Most root rots are caused by the following fungi:Phytophthora, Pythium, Rhizoctonia, andThielaviopsis. Plants of all ages can be infected, andthe degree of infection can vary from light to severedepending on environmental conditions and susceptibil-ity of the plant.

These fungi are soil-borne. The presence of plantroot exudates stimulates Pythium and Phytophthoraspores to move toward and infect the roots. Infectedplants have discolored roots that are reduced in numberand lack healthy, white rootlets.

With chrysanthemums, there is usually a marginalwilting of the leaves, followed by chlorosis and eventuallydeath. The brown leaves remain attached and hang downagainst the stem. These symptoms often begin on onlyone side of the plant and not until after flower buds haveformed. Young, vigorous plants usually have nosymptoms.

The buds on one or two branches of red-floweredgreenhouse rose varieties may turn blue and fail to open;the leaves and the green stem tissues may becomemottled, and when the stem is shaken, the leaves fallfrom the plant. Eventually the stem dies. Additional shootscan develop from basal buds and go through the samesequence, and, eventually, a shoot may remain healthy.Usually there is no vascular discoloration.

With semituberous rooted begonias, some yellowingof leaf margins can occur, but the most distinctivesymptom is the development of an extremely shiny lowerleaf surface.

The most important bacterial wilt pathogen in Con-necticut is Xanthomonas campestris. Various forms(pathovars) of Xanthomonas campestris exist which at-tack specific hosts. For example, Xanthomonascampestris pv. pelargonii causes bacterial blight of Pel-argonium species, and Xanthomonas campestris pv.syngonii causes bacterial blight of Syngonium. See thesection on bacterial diseases for more information onXanthomonas blight of geraniums. Wilt diseases may alsobe caused by three other bacteria, Erwinia carotovora,Erwinia chrysanthemi, and Pseudomonassolanacearum. They are usually serious only at tem-peratures above 27°C.

Bacteria require wounds or natural openings, usu-ally on leaves and stems, to enter plants. Fungal wiltpathogens enter plants primarily through the roots. Theydo not require wounds. Both bacteria and fungi can bespread in propagative material, by water movementthrough soil, by soil movement, by equipment (espe-cially cutting knives), by contaminated flats, and by splash-ing water. Wilt fungi can survive free in the soil for sev-eral years, whereas bacterial wilt pathogens generallysurvive for only one to six months in soil. Both havegood survival rates in infected plant debris.

High temperatures and high relative humidity gener-ally favor the wilt diseases. Conditions which contributeto plant stress will also increase disease severity. Thereare no effective fungicides or bactericides available forthe control of wilt diseases. Infected plants must usuallybe rogued-out and destroyed.

Root rot of Ranunculus, caused by Pythium.A healthy plant is shown on the right.

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Environmental conditions play an important role inroot rot diseases. Factors which stress plants can dam-age roots. These include over or under watering, toohigh or too low temperatures, high salts, and chemicaldamage. Secondary organisms that might not cause dis-eases on their own may then invade the injured tissueand cause further damage. Insects, such as fungus gnatlarvae, can spread the fungi and provide an entry sitethrough feeding wounds. Maintaining conditions that arefavorable for plant growth and promoting overall planthealth will reduce disease severity.

Root rot pathogens are common, naturally occur-ring organisms. Irrigation water from storage ponds thathas been collected from run-off water may contain rootrot pathogens, whereas water from municipal treatmentsystems, or deep wells is normally pathogen-free. Mostnatural soils contain a diverse population of microorgan-isms, including those that cause root rot. Artificial grow-ing media such as perlite, vermiculite, and rockwool startoff sterile and slowly build up low populations of micro-organisms during the crop cycle. If a pathogenic organ-ism is accidentally introduced into this sterile media, thereare few naturally antagonistic fungi or bacteria to sup-press it. This gives the pathogen the opportunity tospread. Naturally occurring media components, for ex-ample peat moss, may contain pathogenic fungi, such asPythium.

Prevention

Use pasteurized or sterile media.Use porous, well-drained media.Avoid watering with cold water.Don’t overwater.Maintain optimum root temperatures.Maintain proper soil pH for the crop.Don’t propagate from diseased plant material.Handle plants carefully and use proper sanitationduring transplanting.Control fungus gnats (see Section 9).Clean tools, hoses, walkways, benches, pots, andtables between crops.

Pythium and Phytophthora Root Rots

The cortex, the outer covering of roots infected withPythium or Phytophthora is usually rotted, and slidesoff easily leaving the string-like vascular bundles behind.Roots are generally soft, mushy, and various shades ofbrown. Above-ground symptoms of infected plants in-clude stunting, wilting, and yellowing as a result of nutri-

Above, stems from young poinsettia plantsshowing Rhizoctonia stem-rot lesions, and rootsrotted off by Thielviopsis. Below, poinsettiastems with swollen and cracked bark caused byThielviopsis infection.

Stem rot caused by Rhizoctoniasolani on an unrootedpoinsettia cutting.

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ent deficiencies occurring from root loss. Most orna-mental crops are susceptible to at least one of these fungi.High soil moisture favors Pythium and Phytophthora.

Rhizoctonia Root Rot

Infected roots are often reddish-brown, with a dryrot. Cool, moderately wet conditions encourage Rhizoc-tonia. This disease can cause infections of the stem aswell as the roots. Above ground symptoms include stunt-ing and yellowing.

Thielaviopsis Root Rot

Thielaviopsis causes black root rot on cyclamen,fuchsias, geraniums, impatiens, kalanchoes, pansies, pe-tunias, poinsettias, primulas and other crops. Infectedroots may have black lesions covering all or part of theroot. This can be observed after the growing mix hasbeen washed off with water. Above ground plant partsare stunted and have yellow leaves.

Wet soils, and neutral or alkaline pH levels favor blackroot rot. Plant stress arising from factors such as highsoluble salts or excessive fungicide applications can alsopromote disease development. Prevention is the bestmethod of controlling black root rot.

BOTRYTIS (GREY MOLD)

Botrytis infects the immature, senescent, andwounded tissues of many crops. It can also infect healthytissue if conditions are well suited to the fungus, or if apiece of infected plant material such as a flower petalcomes in contact with healthy leaves or stems. Opti-mum conditions for Botrytis growth are 18 - 28°C, andhigh humidity or free moisture. Free moisture occurswhen plant tissue temperature drops and relative humid-ity is high. The temperature drop may be only one ortwo degrees, but if the dewpoint is reached, water con-denses on plant parts. It occurs most often just aftersunset when plant tissue temperatures drop more rap-idly than air temperatures, or in the morning when airtemperatures rise quickly. If the greenhouse environmen-tal controls are not quick enough to respond to thesechanges, Botrytis can become established.

Infected tissue first appears as tan or brown water-soaked areas that may become grey upon drying out.Infected flower petals usually show small water-soakedareas which enlarge rapidly and then turn brown or black.The characteristic signs of Botrytis are the fuzzy grayspore masses that develop on infected tissue.

Botrytis is almost always present in greenhouses.New infections occur when conditions are optimum forspore spread and germination. Spores are spread by aircurrents and splashing water. Botrytis overwinters in soiland plant debris.

Prevention

Ensure adequate air circulation through the plants.The disease will not be controlled by chemicals untilthe circulation problem is corrected.Keep relative humidity below 90% by heating orventing of moist air.Don’t overcrowd plants.Minimize dripping of water onto plants from roofcondensation or overhead sprinklers.Remove dead or diseased plant material from thegreen house site.

Above, geranium leaves with lesions caused byBotrytis blight. Such lesions develop where infectedpetals fall on healthy leaves. Below, blightedterminals of rose plants caused by infection withbotrytis blight.

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Don’t leave large stubs or joints on stock plantsafter taking cuttings.Remove senescent flowers and leaves before theydrop onto other plant parts.

POWDERY MILDEW

Powdery mildew is sometimes confused with sprayresidue because it causes whitish-grey patches of fungalgrowth on the upper leaf surface. Lower leaf surfaces,flowers, and stems may also be infected. Many orna-mental crops are infected by powdery mildew fungi. Itcauses serious economic losses through loss of plant vigor,a reduction in the number of blooms, and reduced aes-thetic appeal.

Powdery mildews can occur in a warm, dry envi-ronment, or in a cool to warm, humid environment.Spores will release, germinate, and cause infection with-out a film of water on the plant surface. A fairly highrelative humidity is all that is required for the initial in-fection. Once the plant is infected, the fungus can con-tinue to grow regardless of the relative humidity. Sporesof the powdery mildew fungus are spread by air move-ment. The fungus grows on the leaf surface but obtainsnutrients from the plant by penetrating into leaf cellswith specialized structures called haustoria. Dead mil-dew can remain visible on the plant surface for manydays so check the efficacy of control by examining newgrowth for signs of fresh mildew outbreaks.

Prevention

Eliminate weeds in and around the outside perim-eter of the greenhouse. Some may be hosts for pow-dery mildew.Carefully monitor humidity levels to avoid high hu-midities or large swings in humidity.Maintain optimum plant growing temperatures.

DOWNY MILDEW

Roses, snapdragons, cineraria, and violas may beinfected by downy mildew during periods of cool tem-peratures and high humidity. The fungus, which is re-lated to Pythium and Phytophthora, actually grows in-side the plant tissue. It may produce reddish-purple leafsplotches on the top surface of the leaf. When humidity

levels are high, a mauve-grey, felt-like mat appears, usu-ally on the bottom surface of the leaf. Many spores arepresent in the mat and can be spread from plant to plantvia air movement. The fungus carries over to new cropson dead plant material or through persistence in the soil.

Prevention

Monitor for infections.Control humidity to prevent condensation on thecrop.Clean up all crop debris at the end of the seasonand remove from the greenhouse site.Alternate crops, if possible.

RUSTS

Rust diseases appear initially as small, yellow swell-ings. These grow and produce rusty blisters which willcontain either white, yellow, orange, brown or blackspores. The pustules are often on the underside of theleaves, but may occur on the top surface and/or stemsdepending on the rust species and the stage in the lifecycle. The leaf surface directly above the pustule is fre-

Two zinnia leaves affected by powdery mildew,top and center; healthy leaf below. The centerleaf is severely infected; individual infectionscan be distinguished on the top leaf.

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quently yellow. Many rusts have complex life cycles,requiring two different plant species as hosts. Some rustscan cause systemic infections in their hosts so the plantmay be infected but not show any symptoms.

Spores are spread by moving air currents or splash-ing water or moving air, and require wet conditions forinfection. There are several important rust diseases ofgreenhouse ornamentals, notably on asters, carnations,chrysanthemums, fuchsias, geraniums, and snapdragons.

Rusts are obligate pathogens and usually are host spe-cific, although several species from the same family maybe infected.

Prevention

Inspect new plant materials carefully beforebringing them into the greenhouse.Avoid wetting foliage.Remove and destroy infected plant parts where pos-sible.

BACTERIAL DISEASES

Bacterial diseases are not as common as fungal dis-eases, but they can be very destructive and are difficultto control in the greenhouse. It is not easy to visuallydifferentiate between bacterial and fungal infections, soan early accurate diagnosis is essential in choosing thecorrect management technique.

Bacteria can cause leaf spots, wilts, rots, and blights.Bacterial leaf spots usually appear as circular or angularwater soaked areas. They may be light green or yellow,becoming brown or black as the disease progresses. Some-times a halo can be observed around the center of thelesion when held to the light. Some leaf spots may ex-ude ooze of various colors, and the spots may eventu-ally coalesce. The veins leading from these lesions maybe discolored as bacteria spread through the vascularsystem.

On above-ground plant parts, bacteria require freemoisture for infection, which can be provided by con-densation, overhead watering or splashing water. Bacte-ria are spread during pruning, propagating, and by splash-ing water. Pruning and propagating are particularly ef-fective means of spreading disease, as bacteria requirewounds or natural openings to enter the plant. Begonias,chrysanthemums, geraniums, hibiscus and foliage plantsall have recognized bacterial diseases. Most fungicideshave no effect on bacterial diseases. Prevention is theonly effective control of bacterial diseases.

Geranium leaf affected by bacterial leaf spot.

Prevention

Use disease-free propagative stock.Avoid wetting foliage.Minimize plant wounding.Space plants to provide good air circulation.Disinfect cutting tools and propagating areas.

Xanthomonas Blight of Geraniums

Bacterial blight caused by Xanthomonas campestrispv pelargonii is the single most important disease ofgeraniums. This disease becomes systemic in the plantand can quickly kill it. Bacterial blight may occur wher-ever geraniums are grown and is a continual threat toproduction.

Xanthomonas bacterial blight infects all varieties ofzonal, ivy, seedling, florist, and regal geraniums. Ivy leafgeraniums (Pelargonium peltatum) are especially sus-ceptible while Lady and Martha Washington types (P.domesticum), and specialty types (P. acerfolium, P.‘Torento’, P. tometosum, and P. scarboroviae) have atolerance to the disease but can act as carriers.

Xanthomonas can survive on the leaves or woundedstems of several ornamental species such as tuberousbegonia, chrysanthemum, coleus, fuschia, impatiens, lan-tana, verbena and vinca.

Steps to Early Detection of Bacterial Blight

Routinely check geraniums for symptoms and bevery suspicious of any signs of wilting. Symptoms de-velop very slowly when the temperature is below 21°C.

1) Look for dark brown, sunken leaf spots 1.5 - 3 mmin diameter. Notice: Not all geranium varieties willshow leaf spot symptoms.

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2) Look for V-shaped yellow wedges that form at theleaf margin and taper down to the base of the leaf.The wedge is usually bound by leaf veins on bothsides. Botrytis can cause similar symptoms, butthese infections usually do not taper down to theleaf base and are not restricted by leaf veins.

3) Cut the leaf petiole at the base and the stem in halfto check for a dark discolouration in the vasculartissue.

There is no effective chemical control for geraniumbacterial blight. Fungicides will not control a bacterialdisease. Fixed copper may suppress disease spread butwill have no effect on plants that are already infectedwith bacteria that spread systemically throughout theplant.

Strict sanitation combined with the exclusive use ofculture virus indexed (CVI) stock from reputable propa-gators is the only way to minimize losses from bacterialblight.

Avoid, as much as possible, splashing the plants dur-ing watering. Bacterial blight is readily disseminated bysplashing water which spreads bacteria to leaf surfaceswhere infection occurs through the leaf stomata. Pesti-cide spraying for insects or other diseases that causewater splashing that may spread bacterial blight. Bacte-rial blight is readily spread by the use of common root-ing beds and water films including capillary mats, ebband flow benches, and trough irrigation systems.

Sanitizing the Greenhouse After a BacterialBlight Outbreak

1) Discard all geraniums at the end of the seasonand wash down all bench surfaces with bleach,Formalin(formaldehyde, 1:40 dilution) or quater-nary ammonium compounds (follow label direc-tions). Do not mix these compounds as hazardousgases can result.

2) Purchase CVI disease-free plants each year anduse a sterile, soilless mix.

3) Do not save outdoor-grown geranium plants for useas stock plants.

4) Discard all plants returned by customers and do notallow such plants to be brought into the growingareas.

5) Break off branches from stock plants for propaga-tion rather than using cutting knives.

Geranium cuttings affected by bacterial stemrot caused by Xanthomonas pelargonii. Someof the cuttings in this lot had been attackedby Pythium also, as sometimes occurs.

Geranium plant affected by bacterial stem rot.Tissues of stem and upper roots areblackened.

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6) Avoid splashing when watering.

7) Immediately discard all plants found to be infected,wash down benches and disinfect all tools, flats,pots, etc., used to handle the plant.

8) Keep hoses off the ground.

9) Limit entry into stock and production areas.

10) Avoid plant-to-plant contact, common water films(capillary mats, ebb and flow benches, trough irri-gation systems) and overhead watering particularlyfor stock plants.

11) Keep exact records of plant sources when takingcuttings so that batches can be traced back to aninfected source and all infected material can be de-stroyed.

12) Dispose of infected plants away from the greenhouse site. Do not compost diseased plant mate-rial.

13) Start work from the cleanest production area to thedirtiest, i.e. stock plants to propagation area toproduction area and ending at the cull pile. Do notwork in the reverse direction from the cull pile.

VIRAL DISEASES

Viral diseases are usually first observed as colorchanges, spots, streaks, rings, and mottling on leaves.Leaves may also exhibit distorted growth. Flower symp-toms include dwarfing, streaking, deformities, and colorchanges. Virus infected plants may be stunted, particu-larly if infected when young.

Symptoms can be masked, and plants may appearto grow out of the infection under certain conditions,such as warmer temperatures. However, once a plant isinfected with a virus, it remains so indefinitely. Thereare no pesticides to cure virus infections.

Viruses may be transmitted by insect feeding, crophandling, and infected propagation material. Each virusdisease has different requirements for control so it isimportant to have the virus identified.

Tomato spotted wilt virus (TSWV) and impatiensnecrotic spot virus (INSV) can infect over 300 plantspecies, including many ornamentals. They are spreadby thrips and infected plant material, but not easily bycrop handling.

Tomato Spotted Wilt Virus/ImpatiensNecrotic Spot Virus

The two strains of tomato spotted wilt virus (impa-tiens and lettuce) are now recognized as two separatediseases. The impatiens strain has been renamed ‘impa-tiens necrotic spot virus’ (INSV) while the lettuce strainhas retained the original name ‘tomato spotted wilt vi-rus’ (TSWV). INSV infects floriculture crops more fre-quently than TSWV.

Both these viruses cause stunting, leaf distortion,mosaic mottling of leaves, leaf vein clearing, necroticareas on leaves, wavy lines on foliage, chlorotic spots,concentric rings on foliage or flowers, and stem necro-sis. The necrotic lesions on leaves can easily be mis-taken for pesticide damage. The symptoms vary depend-ing on host age, host species, cultivar, the level of nutri-tion, temperature, and the virus strain.

Method of Spread

Both western flower thrips (Frankliniellaoccidentalis) and the onion thrips (Thrips tabaci) canspread TSWV/INSV. The western flower thrips is themost dangerous vector due to its ability to develop in-secticide resistance faster than other thrips species.

Thrips are small (2 - 3 mm long), narrow, light todark brown insects with long fringed wings. They arenot strong fliers but due to their fringed wings and smallsize can be carried long distances by wind and movefrom outside into greenhouses through open doors andvents. Thrips must feed on infected tissue while they

Necrotic ring spot ongladiolus leaf infectedwith the tobacco ring-spot virus.

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are larvae to acquire the virus. They introduce the virusinto plants when their stylet pierces the leaf tissue. Oncea thrips picks up the virus it remains infected for the restof its life. During this period many plants can be in-fected. There is a direct relationship between the num-ber of thrips and incidence of the virus.

Thrips must feed on infected plants for 15 minutesto acquire the virus. There is a latent period of at leastfour days after picking up the virus during which thripscannot transmit the virus.

TSWV/INSV is also reportedly transmissible throughthe seed of cineraria.

Prevention

Control insect pests, particularly aphids and thrips.Use virus-free or virus-resistant propagation mate-rial.Have suspicious looking plants tested for the pres-ence of TSWV/INSV.Destroy plants showing obvious virus symptoms.Keep stock plants in an area separate from grow-ing plants.

Control Strategies

An effective insecticide program is an essential com-ponent in the control of TSWV/INSV, but sole relianceon insecticides to control western flower thrips is a short-term solution due to the development of resistance. Anintegrated approach must be used.

1. Start with clean stock. Plants infected with TSWV/INSV usually have a latent period during whichthey show no symptoms. Also, some hosts may beinfected but remain symptomless and are a threatto more susceptible host that may be present in thegreenhouse. When purchasing cuttings or seedlingsensure there are no thrips on the plant that mayhave already infected them, or that may be a sourceof infection for the crops already in your greenhouse.Keep in-coming stock isolated from production ar-eas until it is certain they are insect and virus free.

2. Monitor western flower thrips populations with yel-low or blue sticky traps. Place cards at the croplevel to monitor any population changes and neardoorways and vents to detect movement of thripsinto the greenhouse.

3. Screen vents and cover open doorways with heavyplastic strips to reduce movement into the greenhouse.

4. Ensure that greenhouses are weed-free and that aweed-free border 10 - 20 feet wide around the greenhouse is maintained. Many weeds are host for thewestern flower thrips and TSWV/INSV. Theground next to doors and vents should have a weed-free border at least 20 feet wide. Avoid plantingsusceptible bedding plants around the greenhouse.

The geranium leaf on the left is affected by a viraldisease; the other leaf is healthy.

Cineraria leaves with symptoms of mosaic virus.

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5. Place potted petunia plants ('pink beauty' or 'min-strel') among your crop along with non-sticky bluecards as attractant to determine if TSWV/INSV ispresent. Leaf spot symptoms will appear on petu-nias within 3 - 5 days after infection.

6. Destroy all infected plants. If the virus has beenconfirmed in one or two plants of a certain batch orcultivar you must presume all these plants are po-tentially infected. Spray all diseased plants with aninsecticide to kill thrips on the plants. This preventsviruliferous thrips from flying to healthy cropswhen their host is disturbed. Infected plants shouldbe placed in plastic bags at the bench or bed site toprevent thrips from spreading through the greenhouse as they are carried outside.

7. Bio-control agents are generally not effective forvirus infected thrips on ornamentals because a lowpopulation of the pest remains, and even a low num-ber of virus carrying thrips can cause severe eco-nomic damage.

8. Planting beds should be steam treated or fumigatedto kill thrips and larvae. Larvae are found in thetop few centimeters of soil, so they may be treatedwith a soil spray. Apply as a coarse spray to thesoil surface to kill larvae that drop to pupate, aswell as adults emerging from the soil. Apply 2

sprays: the first when damage is noticed and thesecond two to three weeks later. Repeat if new in-festations occur. See label for mixing and pH re-quirements. Use extra caution when spraying closeto cynara, coleus, episcia, and gloxinias. Crop con-trol may damage open blooms.

9. If the greenhouse is cleared out before a new cropbegins, increasing the temperature to 35°C for 5days or 40°C for 2 - 3 days will help control thripspupae. The pupal stage will be shortened at thesetemperatures and emerging adults will starve be-cause there is no food source.

10. Educate your staff so that they can identify thesymptoms of TSWV/INSV.

95

Tomato Spotted Wilt Virus & Impatiens Necrotic Spot Virus Crop Symptoms

Calceolaria TSWV and INSV cause symptoms on calceolaria which resemble a fungal wilt disease.Central areas, or one-sided wilt patterns develop on leaves with a greasy grey color andplants eventually collapse without recovery.

Chrysanthemum Susceptible chrysanthemum cultivars such as Polaris develop necrotic stem lesions andleaves become necrotic and collapse. Flowering plants have a blighted appearance and lookas though they were infected with Fusarium wilt.

Cineraria Young cineraria may develop symptoms similar to those on gloxinia (see gloxinia) whileolder plants develop ring spots and line patterns on leaves. Dark purple to brown sunkenlesions develop on petioles, frequently at the leaf junction. The petiole may be girdled orthe lesions may move into the stem.

Cyclamen Initial symptoms on cyclamen include necrotic leaf spots and vein necrosis. Occasionally,lesions initiated at the base of the leaf blade radiate along several veins causing an oak-leafpattern. Chlorotic leaf lesions develop into necrotic spots or concentric rings. Leaf collapsecan result from petiole necrosis or coalescence of numerous ring spots. Necrosis in thevascular bundles of the corm has been observed in some plants. Symptom development isoptimum at 13°C. When the temperature is increased to 22°C infected plants tend to besymptomless. Symptoms develop approximately 3 to 4 months after infection when plantsare grown at 13°C.

Exacum TSWV and INSV cause straw-colored necrotic leaf lesions 7 to 14 mm in diameter onexacum. Leaves may become completely necrotic and collapse. Lesions on the stem be-come slightly sunken and light to dark grey or straw colored. On larger plants, one branchor the entire plant may collapse and die.

Gloxinia Infected plants less than six weeks old develop symptoms resembling Phytophthora rootrot. The base and central part of lower leaves darken and plants collapse. Older plantsdevelop spots and line patterns on upper and lower leaf surfaces which begin as chloroticpatterns that become necrotic. Necrotic areas may coalesce and plants develop a raggedappearance. Flowers may become distorted.

Marigold Infected marigolds exhibit leaf strapping symptoms, particularly on the youngest leaves.Marigolds planted outside the greenhouse should be examined for symptoms.

New Guinea Impatiens TSWV and INSV cause local lesions on impatiens that include ring spots and papery ne-crotic areas on leaves. The virus becomes systemic and causes faint purplish ring patternsor a mottle on newer leaves. Growing points may abort. Susceptible cultivars may die, ormore often, some branches will die back while others survive. Mojave, in the Indian series,produces some leaves with necrotic ring and spotting symptoms, but many leaves on theplant are symptomless while cultivars in the Sunshine series are often killed.

Pepper Fruit ripens unevenly if infected after fruit set. If infected before fruit set, fruit developsunevenly and becomes misshapen. Dark brown soft spots may develop on fruit and ringpatterns may occur. Look for stem lesions, petiole, and peduncle necrosis, loss of leadersand branch dieback.

Tomato The most common symptoms are rapid browning of the young leaves followed by cessa-tion of growth. The leaves later become distorted with necrotic spotting and fruit formedafter infection may develop blotches or mottling. None of the cultivars currently beinggrown exhibit resistance.

96

1. What tactic(s) should be used to prevent diseaseproblems in greenhouses?

a. remove weeds and plant debrisb. inspect incoming plants for disease symptomsc. purchase plants from dealers that index their cropsd. all of these

2. Plant diseases may be spread on infested pots ortools.

________True ________False

3. Damping-off is caused by soil-inhabiting fungi.

________True ________False

4. Older plants usually die from damping-off infec-tion.

________True ________False

5. Which plant maintenance practice(s) reduce leafspot problems?

a. over-the-top wateringb. reduced air circulationc. soil surface wateringd. none of these

6. High soluble salt levels in the rooting media maycause plant wilting.

________True ________False

7. Verticillium may persist in the soil for many years.

________True ________False

8. How do bacteria enter plants?

a. through the rootsb. through woundsc. through buds

9. Plants infected with a wilt disease can be treatedusing systemic fungicides.

________True ________False

10. How do you prevent root rot?

a. use pasteurized or sterile mediab. avoid watering with cold waterc. don’t over waterd. all of these

11. High soil moisture favors Rhizoctonia root rot.

________True ________False

12. Greenhouse environmental controls must be con-stantly controlled to prevent development of freemoisture which leads to grey mold.

________True ________False

13. List four factors that will reduce or prevent greymold problems.

a.

b.

c.

d.

SECTION 10 - REVIEW QUESTIONS

Management of Greenhouse Diseases

97

14. Which disease problem is commonly confusedwith spray residue?

a. leaf spotb. powdery mildewc. rustd. botrytis

15. Once a plant is infected, powdery mildew cancontinue to grow when the relative humiditydrops very low.

________True ________False

16. Downy mildew actually grows inside the planttissues.

________True ________False

17. Which disease symptoms appear as a mauve-gray, felt-like mat on the undersides of the leaves?

a. botrytisb. Xanthomonas blightc. tomato spotted wilt virusd. downy mildew

18. Rust diseases appear initially as small, yellowswellings.

________True ________False

19. How are bacterial diseases often spread?

a. by splashing waterb. during pruningc. during propagationd. all of these

20. What is the most important disease affectinggeraniums?

a. tomato spotted wilt virusb. leaf rustc. damping-offd. none of these

21. Strict sanitation combined with exclusive useof culture virus indexed stock is the only way tominimize losses from bacterial blight.

________True ________False

22. List six of the thirteen steps to sanitize a green-house after a bacterial blight outbreak.

a.

b.

c.

d.

e.

f.

23. Viral diseases can be cured with fungicide treat-ments.

________True ________False

24. What insect generally causes the spread of to-mato spotted wilt virus and impatiens necroticspot virus?

a. green peach aphidb. soft shell scalec. thrips

25.Thrips acquire the TSW virus when feeding asadults.

________True ________False

26. An effective insecticide program is a long-termsolution to wilt virus disease prevention.

________True ________False

98

27. List four of the ten TSWV/INSV control strate-gies.

a.

b.

c.

d.

99

SECTION 11

GREENHOUSE WEEDMANAGEMENT

Weed control is an important part of greenhousemanagement. A typical management plan for greenhouseweeds includes a variety of cultural, mechanical andchemical methods to promote crop growth while reducingweed problems. Understanding plant growth habits willaid in selecting the best weed management methods.

Weeds can enter the greenhouse as seeds in thegrowing medium of plants, on tools, pots and machinery,or in any other propagation material. Light seeds areeasily blown by the wind through ventilation systems.

An integrated weed control program is encouraged.This should include control of weeds in and aroundgreenhouses by mowing or cultivating and applyingchemicals, steam pasteurization or fumigation whenappropriate.

REASONS FOR WEED CONTROL

Vigorous, healthy crop plants are the best defenseagainst insect and disease damage. Unfortunately,practices that promote development of the crop alsoencourage the growth of weeds. Weeds adversely affectthe yield of greenhouse crops in several ways:

Weeds directly compete for soil moisture andnutrients.Weed growth can shade young crop plants, delayingtheir development.Dense weed growth impedes harvest, creates a poorimpression on customers and reduces sales.Many weeds harbor diseases, with or withoutevident symptoms, that can infect crop plants.Weeds may be primary or alternate hosts for insectsand related pests.Heavy weed growth can interfere with pesticideapplications, preventing adequate protection.

WEEDS OUTSIDE THE GREENHOUSE

Control of weeds growing outside the greenhousewill eliminate a major source of airborne weed seed.Perennial weeds such as quackgrass or bindweed maygrow under the foundation and into the greenhouse.

Several options are available for controlling weedsoutside the greenhouse. These include mowing, herbicideapplication, mulches, steam pasteurization, fumigationand hand weeding.

Some growers maintain a bare, plant-free areasurrounding the greenhouse. Other growers use mowedgrass. Mowing regularly will prevent a majority of weedsfrom forming seed. Thrips will develop in grass and weedflowers so a regular mowing schedule is important.

Registered postemergent and soil residual herbicidesmay be used in areas immediately adjacent to thegreenhouse. When applying herbicides around thegreenhouse, avoid drift into the structure through thevents. Those herbicides considered safest to use are alsolabeled for use within the greenhouse.

Mulches can effectively control weeds by preventingseed germination at or near the soil surface. Mulches aregenerally used for long-term crops such as roses, outdoorcut flower crops, or as bed preparation. Organic mulches,like sawdust, shredded bark or other plant residue shouldbe applied to weed free soil to a minimum depth of twoinches. Inorganic materials, such as sand, gravel,polypropylene ground covers, or perforated blackpolyethylene film, may also be used. These materialsprovide a weed-resistant surface while allowing waterpenetration. New plastic products have been specificallydesigned for mulching purposes.

Steam pasteurization and soil fumigants will providesignificant weed control. In the case of steam, propertemperature and treatment are necessary. Soil fumigants

100

are used prior to adding fertilizers to the soil, to kill weedseeds that are present (see Section 7 - Fumigation).

Supplement other weed management methods withhand weeding. By integrating sanitation, preemergentherbicides, postemergent herbicides, fumigation, mowingand manual weed removal in a total weed managementprogram, weed pressure will be greatly reduced.

WEEDS INSIDE THE GREENHOUSE

Cultural and mechanical controls

The most important control measure for a weed-free greenhouse is sanitation. Limit the introduction ofweeds by keeping weed seed out of the greenhouse,using sterile growing mixes, introducing only clean plantmaterials, and managing weeds outside the greenhouse.Weeds that enter the greenhouse should be removed byhand or treated with a registered herbicide before theygo to seed.

If weeds are already established in the greenhouse,they can be eliminated by:

Manual removalEmptying the greenhouse and allowing it to dry upEmptying the greenhouse and using a postemergentherbicide.Each of these methods will remove the vegetation

that is present but will do nothing to preventreestablishment from seed that is present. If continuousremoval is too expensive and time consuming, tryapplying a registered residual herbicide.

Chemical control of weeds

Restrictions on the use of herbicides in greenhousesare very specific. No currently registered herbicides may

be used in pots or on benches. The herbicides labeledfor use in greenhouses may only be applied on the flooror underneath benches. Some herbicides can only beapplied in an empty greenhouse. Plants can usually bebrought into the treated area almost immediately aftertreatment. Other herbicides can be applied in a greenhousewhile a crop is present. REI and PPE requirements varywith the material being used. Be sure to read the entireproduct label before mixing or applying herbicides. Seethe current New England Greenhouse Floricultural CropPest Management and Growth Regulation Guide forspecific herbicide recommendations.

ALGAE

The greenhouse provides an ideal environmentfor algal growth. Left unchecked, algae will grow onwalks, water pipes, equipment, greenhouse coverings and,on or under benches. It can reduce light levels to thecrop, provide a breeding ground for insect pests like fun-gus gnats, harbor disease organisms, reduce efficiencyof irrigation and cooling equipment, and be a liabilityrisk for workers and customers using slippery walkways.

The primary control is through environmentalmodification and sanitation. Foremost is the reductionof moisture on the floors, benches, and structural sur-faces. Proper ventilation will also reduce the amount ofmoisture in the greenhouse. Exchanging the internal moistair with external dry air is an effective method of lower-ing greenhouse moisture. Horizontal Air Flow (HAF) willhelp keep the internal greenhouse surfaces dry. Water-ing should be directed to the growing containers. Thegreenhouse floor should be level and drain properly toprevent pooling of water. The use of porous concrete orsand in construction will prevent puddling if surfaces arekept free of dirt and debris.

Sanitation is very important in algae control. Allsurfaces should be kept clean of plant debris and weeds.Algae control on capillary watering mats can be achievedby excluding light with a barrier, such as perforated blackplastic film. On the greenhouse floor, black polypropy-lene ground cover fabrics will curtail algal growth.

Currently there are several registered chemicals thatmay be used for algae control. These products are alsouseful biocides that may control bacteria, fungi, and vi-ruses on greenhouse surfaces. See the current New En-gland Greenhouse Floricultural Crop Pest Managementand Growth Regulation Guide for specific recommen-dations.

Yellow wood sorrel (Oxalis stricta or O. europaea),a perennial greenhouse weed that seeds profusely.

101

1. A major method of controlling weeds in green-houses is elimination of weeds around the pe-rimeter of the greenhouse.

________True ________False

2. Regular mowing of plants around greenhouseshelps discourage thrips populations.

________True ________False

3. List four ways to manage weeds outside thegreenhouse.

a.

b.

c.

d.

4. Sanitation is the most important measure for aweed free greenhouse.

________True ________False

5. How can established weeds be eliminated froma greenhouse?

a. manual removalb. emptying the greenhouse and allowing it to dry

upc. emptying the greenhouse and using a postemergent

herbicided. all of these

6. Most herbicides registered for greenhouse usemay be applied in pots or on benches.

________True ________False

7. Algae can be controlled by reducing moisture onfloors, benches and structural surfaces.

________True ________False

8. List three methods for reducing algae problems.

a.

b.

c.

SECTION 11- REVIEW QUESTIONS

Greenhouse Weed Management

102

The following crop production and greenhousemanagement reference books are available from severalhorticultural industry clearinghouses or from bookstores,unless otherwise noted. Prices and availability are cur-rent September 1994.

Armitage, A. A. 1993. Specialty Cut Flowers. 372pp. Varsity Press, Portland, OR.

Ball, Vic, ed. 1991. Ball Red Book. (15th ed.).From GrowerTalks Bookshelf, 1-800-456-0132. $60.00.Practical grower’s manual with 15 sections on green-house structures, heating, computerization, mechaniza-tion, etc.; 5 sections on plug production; 6 sections onpest management, and 12 sections on general crop cul-ture. Includes details on 120 crops.

Bedding Plants III. 1985. 560 pages. This manualcovers all aspects of bedding plant production, and in-cludes information about plug production. $24.95.

Chase, A.R. 1987. Compendium of OrnamentalFoliage Plant Diseases. A.P.S. Press, St. Paul, MN., 92pages.1-800-328-7560. $35.00.

GREENHOUSE REFERENCES

Chase, A. R., M. Daughtrey, and G. W. Simone.1995. Diseases of Annuals and Perennials. Ball Publish-ing, Batavia, IL. 202 pp.

Daughtrey, M. and Chase, A.R. 1992. Ball FieldGuide to Diseases of Greenhouse Ornamentals. 218 pp.GrowerTalks Bookshelf, 1-800-456-0132. Over 500color photos for quick grower ID.

Daughtrey, M., R. Wick and J. Peterson. 1995.Compendium of Flowering Potted Plant Diseases. APSPress, 3340 Pilot Knob Rd., St. Paul, MN 55121. 1-800-328-7560. $35.00.

De Hertogh, A. Holland Bulb Forcer’s Guide. 4thed. Available from Professional Plant Growers Assn.,Attn. Deborah Norton, 1980 North College Road, Ma-son, MI 48854. $30.00, complete reference for cut andpotted bulb production in the greenhouse.

Ecke, P., Jr., O.A. Matkin, and D.E. Hartley. 1990.The Poinsettia Manual. 3rd ed. Encinitas CA: Paul EckePoinsettias. 267 pages. $49.95 incl UPS shipping. Avail-able from Paul Ecke Poinsettias, Encinitas CA; 619-753-1134. Complete and well-indexed manual on productionand marketing of poinsettias.

Gentile, A.G. & D. T. Scanlon. 1992. A Guide toInsects and Related Pests of Floricultural Crops in NewEngland. Revised in 1992 by Tina M. Smith. Descrip-tions, color photos, lifecycles and habits of insects andrelated pests of floriculture crops. Available for $10 fromUniversity of Massachusetts Cooperative Extension Sys-tem, Bulletin Distribution Center, Cottage A, ThatcherWay, Amherst, MA 01003-0051.

Holcomb, E.J., ed. Bedding Plants IV. 1994. 4thed. will be available from GrowerTalks Bookshelf, 1-800-456-0132, $55.00. Complete production guide tobedding plant production, including plug production.

PRODUCTION REFERENCES

APPENDIX A

103

1994 Integrated Pest Management for FloristCrops. Part of the Cornell Recommendations series.Publication #141RGFC2. Available from Cornell Uni-versity Resource Center, 607-255-2080. $14.00

Jarvis, W.R. 1992. Managing Diseases in Green-house Crops. A.P.S. Press, St. Paul, MN, 288 pp. 1-800-328-7560. $79.00.

Larson, Roy, A. 1992. Introduction to Floriculture.2nd ed. New York: Academic Press. 636 pages. $50.00.Crop production manual with 22 chapters cover 22 ma-jor crops, including foliage plants, bedding plants, sev-eral cut flowers and several potted flowering plants.

Nelson, Paul. 1991. Greenhouse Operation andManagement. Englewood Cliffs, NJ: Prentice-Hall. 612pages. $56.00. Basic reference book on greenhouse op-eration and management. A standard textbook for green-house management courses.

New England Greenhouse Floricultural Recommen-dations, A Management Guide for Insects, Diseases,Weeds and Growth Regulators. 1997-8. 156 pages. Acollaborative effort among the six New England states;this guide contains information on IPM, pesticides,biocontrol, biorationals, etc. $15.00. (Replaces New En-gland Greenhouse Floricultural Crop Pest Managementand Growth Regulator Guide 1995-1996.)

Ohio State “Tips” Series: Poinsettias; Potted Eas-ter Lilies; Zonal Geraniums; Bedding Plants; Potted Pe-rennials and / Biennials; and Potted Chrysanthemums.Approx. 80 pages each. Available from Ohio State Uni-versity Cooperative Extension Bulletin Office, 614-292-1607. $ 12 each.

Powell, C.C. and R.K. Lindquist. The Ball Pestand Disease Manual. 1992. 332 pp. Ball Publishing,Batavia, lL 60510. All aspects covered from ID to con-trols.

Strider, David, L. 1985. Diseases of Floral Crops,Volumes 1 & 2, Praeger Publishers, New York, N.Y.,1212 pages.

White, John., W., ed. Geraniums IV. 1993. 4th ed.Publ. formerly by Pennsylvania Flower Growers. 412pages $53.00, available from GrowerTalks Bookshelf,1-800 4564132. Complete production guide to zonal ge-raniums.

FLORICULTURAL ASSOCIATIONS

Association of Specialty Cut Flower Growers (ASCFG)

ASCFG was formed to unite growersengaged in the production and marketing ofspecialty floral crops. The group is dedicatedto improving the industry by fostering friendshipand sharing through conferences, tours,seminars and shows; publishing informationpertinent to the industry through a bulletin;generating research on producing, handling andmarketing specialty cut flowers; and educatingdistributors and the general public aboutspecialty cut flowers. For more informationabout ASCFG, contact Judy Laushman,Executive Director, 155 Elm Street, Oberlin,Ohio 44074.

Perennial Plant Association (PPA)

PPA member benefits include a quarterlynewsletter, proceedings from the group’s annualSymposium, and a membership directory. PPAsponsors seminars, regional meetings, andresearch on perennials. For more information,contact Dr. Steven Still, Executive Secretary,PPA, 3383 Schirtzinger Road, Hilliard, Ohio43026.

Professional Plant Growers Association (PPGA)

PPGA represents primarily greenhousegrowers of container plants — flowering pottedplants, foliage plants and bedding plants. Theassociation sponsors several educationalprograms each year, publishes a newsletter andproduces educational materials for growers,including videos and written crop manuals. Formore information, contact PPGA, PO Box27517, Lansing, Michigan 48909.

The Herbal Connection

The Herbal Connection offers a bimonthlynewsletter, an annual resource guide, and aninformation service to answer members’ herbproduction/marketing questions. For moreinformation, contact The Herbal Connection,3343 Nolt Road, Lancaster, PA 17601.

104

The Sun Room:http://www.prairienet.org/ag/garden/sunroom.htm

University of Minnesota Commercial FloricultureServices:http://134.84.58.52/ComFlor.html

OTHER INFORMATION SOURCES

Department of Environmental Protection (DEP)Waste Management BureauPesticide Management Division79 Elm StreetHartford, CT 06106Phone: (860) 424-3369 FAX: (860) 424-4060

Department of Agriculture165 Capitol AvenueHartford, CT 06106Phone: (860) 566-4667 FAX: (860) 566-6576

PAT OfficeNorthern District Cooperative Extension CentersWest Hartford CampusThe University of Connecticut1800 Asylum AvenueWest Hartford, CT 06117Phone: (860) 241-4940 FAX: (860) 241-4960

COOPERATIVE EXTENSION OFFICES

Eastern District Cooperative Extension Offices

562 New London TnpkNorwich, CT 06360Phone: (860) 887-1608 FAX: (860) 886-1164

139 Wolf Den RoadBrooklyn, CT 06234Phone: (860) 774-9600 FAX: (860) 774-9280

1066 Saybrook Road, Box 70Haddam, CTPhone: (860) 345-4511 FAX: (860) 345-3357

JOURNALS

Greenhouse Grower. 14 issues/yr. $25. MeisterPublishing Co., 37733 Euclid Avenue, Willoughby OH44094.

Greenhouse Manager. 12 issues/yr. $24. Branch-SmithPublishing, 120 St. Louis Ave., Fort Worth, TX 76104.

Grower Talks. 12 issues/yr. $22. PO Box 532, Geneva,IL 60134-0532.

Greenhouse Product News. 6 issues/yr. $24. ScrantonGillette Communications, Inc. 380 E. Northwest Hwy.,Des Plaines, IL 60016-2282.

The IPM Practitioner. 10 issues/yr. $35. PO Box 7414,Berkeley, CA 94707.

INTERNET RESOURCES

There are a few sites on the world wide web withuseful information. The following locations may be use-ful.

Commercial Greenhouse Programs:http://aggie-horticulture.tamu.edu/greenhouse/comgreen.html

North Carolina State University Floriculture Page:http://ww2.ncsu.edu/ncsu/cals/hort_sci/floriculture/

PlantNet.Com:http://www.plantnet.com

Information on floriculture research.

Texas Plant Disease Handbook:http://cygnus.tamu.edu/texlab/table.html

The African Violet Page:http://aggie-hoticulture.tamu.edu/violet/violet.html

The Horticultural Web:http://www.webdev.com

Provides interactive databases on varieties,research, government regulations, and products.

105

Sea Grant Marine Advisory ProgramThe University of Connecticut at Avery Point1084 Shennecosseett RoadGroton, CT 06340-6097Phone: (860) 445-8664 FAX: (860) 445-3458

Northern District Cooperative Extension Centers

West Hartford CampusThe University of Connecticut1800 Asylum AvenueWest Hartford, CT 06117Phone: (860) 241-4940 FAX: (860) 241-4960

1305 Winstead RoadTorrington, CT 06790Phone: (860) 626-6240 FAX: (860) 626-8849

24 Hyde AvenueVernon, CT 06066Phone: (860) 875-3331 FAX: (860) 875-0220

Southern District Cooperstive Extension Centers

305 Skiff StreetNorth Haven, CT 06473Phone: (203) 789-7865 FAX: (203) 789-6461

Bridgeport Expanded Food and Nutrition, UrbanGardening, and 4-H/Youth Development EducationPrograms

1374 Barum AvenueBridgeport, CT 06610Phone: (203) 579-6302 FAX: (203) 579-6037

State Administrative Office

Cooperative Extension SystemCollege of Agriculture and Natural ResourcesThe University of Connecticut1376 Storrs RoadStorrs, CT 06269-4036Phone: (860) 486-4128

106

BIOLOGICAL CONTROL

APPENDIX B

DIRECTORY OF BENEFICIAL ORGANISMS

This appendix has been adapted from "Suppliers ofBeneficial Organisms in North America," Edited byCharles D. Hunter, California Environmental ProtectionAgency, Department of Pesticide Regulation, Environ-mental Monitoring and Pest Management Branch, 1994Edition. One free copy per request is available from:

California Environmental Protection AgencyDepartment of Pesticide Regulation

Environmental Monitoring and Pest ManagementBranch

1020 N Street, Room 161Sacramento, California 95814-5604

Telephone (916) 324-4100

It is also available on the internet at http://www.cdpr.ca.gov/docs/dprdocs/goodbug/organism.htm.

This listing is confined to beneficial organisms usedfor the biological control of pest organisms in green-houses and excludes other commercially available use-ful organisms such as honey bees, earthworms, or but-terflies as indexed listings.

Biological controls that are single-celled organismssuch as bacteria, fungi, protozoans, and viruses are de-fined as pesticides by the United States EnvironmentalProtection Agency (USEPA). In the United States ofAmerica (USA), the sale and use of these organisms isgoverned by USEPA and state laws, and regulations ap-plicable to chemical pesticides. These organisms arewidely available commercially and are not listed in thispublication.

This appendix lists some 50 different organismsavailable from 81 suppliers. Only private commercialsuppliers are listed. The suppliers of each country havebeen listed separately.

In each section, the suppliers are listed alphabeti-cally with each listing preceded by a supplier number.Each supplier number begins with the first letter of the

country in which the supplier is located (C=Canada,M=Mexico, U=USA). Each listing includes the name,address, telephone, and FAX numbers of the supplieralong with a retail/wholesale notation. Under the retail/wholesale notation, there may also be a brief commentsubmitted by the supplier on its specialties and/or theservices it can provide. All the information on Mexicansuppliers was obtained from Ing. Enrique GarzaGonzalez, Centro Nacional de Referencia de ControlBiologico (Sanidad Vegetal).

Scientific names are used because most beneficialorganisms do not have common names.

This listing gives only a general description of thebeneficial organisms and makes no recommendations norimplies their effectiveness in controlling any pest. Thebeneficial organisms listed may attack other organismsthat are not listed. Before using any type of pest control,be sure of the identity of the pest(s). Sometimes, benefi-cial organisms are confused with pests, especially in theirimmature stages, and control measures are mistakenlyapplied.

In addition to offering biological controls, some ofthe companies listed can provide consultation services.These services can be extremely valuable in establishingintegrated pest management (IPM) programs of whichbiological controls are a major part. Many of the suppli-ers also have literature available about beneficial organ-isms and how to use them.

Encarsia formosa - whitefly parasite

107

IMPORTANT NOTICE

With the proper permits, most of the organisms listedin this booklet can be shipped interstate and in manycases between countries. The suppliers should be awareof the permits required and may often have the permitson hand to ship to your area. In some cases, suppliersmay require assistance in obtaining permits. In some situ-ations, the importation or transport of certain species isprohibited.

The importation and transportation of live insects ormicrobial agents may require a permit. For further infor-mation contact: Louis Magnarelli, Connecticut Agricul-tural Experiment Station, 123 Huntington Street, NewHaven, CT 065211,Phone: (203) 789-7241, FAX: (203) 789-7232.

CANADA- Commercial Suppliers

C01 Applied Bio-Nomics Ltd.11074 West Saanich RoadSidney, British ColumbiaCANADA V8L SP5Telephones: (604) 656-2123 (Insectary) (604) 940-0290 (BC) (416) 793-7000 (ONT)FAX: (604) 656-3844Retail and wholesale. Distributor list available. Free literature and price list.

C02 Better Yield InsectsRR3Belle River, OntarioCANADA NOR 1A0Telephone: (519) 727-6108FAX: (519) 727-5989Retail and wholesale. Free consultation. Catalog $ 1

C03 Canadian Insectaries5 Alderwood RoadWinnipeg, ManitobaCANADA R2J 2K7Telephone: (204) 257-3775FAX: (204) 256-2206Retail and wholesale. Price list available. FAX/Mail orders preferable. Permit needed for U.S.A. import.

C04 Coast Agri Ltd.464 Riverside Road South RR#2Abbotsford, British ColumbiaCANADA V2S 4N2Telephone: (604) 853-4836FAX: (604) 853-8419Retail and wholesale. IPM consulting. Free catalog. Need permit for U.S.A. import.

An Encarsia sp. wasp.Actual size 0.75 mm.

108

C05 Koppert Canada Ltd.3 Pullman CourtScarborough, OntarioCANADA M1X 1E4Telephones: (416) 291-0040, (800) 567-4195FAX: (416) 219-0902Retail and wholesale. Free literature and pricing available upon request.

C06 Manbico BiologicalBox 17, GRP 242, RR2Winnipeg, ManitobaCANADA R3C 2E6Telephones: (204) 697-0863, (800) 665-2494 (Canada)FAX: (204) 697-0887Retail and wholesale. Free catalog. Consulting.

C07 Natural Insect ControlRR #2Stevensville, OntarioCANADA L0S 1S0Telephone: (905) 382-2904FAX: (905) 382-4418Retail and wholesale. 36 page catalog. Permit for N.Y., other states pending.

C08 Nature’s Alternative Insectary Ltd.Box 19 Dawson Road,1636 East Island HighwayNanoose Bay, British ColumbiaCANADA V0R 2S0Telephones: (604) 468-7912, (604) 468-7911FAX: (604) 468-7912Retail and wholesale.Producer. Available year round.Weekly shipments within U.S.A. Phone/FAX for brochure.

C09 Richters357 Highway 47Goodwood, OntarioCANADA L0C 1A0Telephone: (905) 640-6677 FAX: (905) 640-6641Retail only. Years of experience using beneficials for pests on herbs. Catalog $2.

C10 Westgro Sales Inc.7333 Progress WayDelta, British ColumbiaCANADA V4G 1E7Telephone: (604) 940-0290FAX: (604) 940-0258Retail and wholesale. Literature and price list available upon request.

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MEXICO - Commercial Suppliers

CREROB - Centro Regional de Reproductores de Organismos Beneficos. Son insectarios que fueron transferidosde manos del gobierno a compaffias privadas y que ahora vendee al publico = “ Regional Center of Reproducers ofBeneficial Organisms.”

These are insectaries that were transferred from the Mexican Government to private ownership and now sellto the public.

M01 CREROB - CaborcaAv. “P” y Calle ObregonCaborca, SonoraMEXICOTelephone: (637) 2-08-71Retail and wholesale.

M02 CREROB - MatamorosSendero Nacional Km. lApartado Postal No. 550 Matamoros, TamaulipasMEXICOTelephone: (891) 2-12-02Retail and wholesale.

M03 CREROB - MexicaliKm. 1.5 Carretera a Mexicali-San Felipe, CP 21230Mexicali, Baja Califonia NorteMEXICOTelephone: (65) 61-70-80FAX: (65) 61-94-28Retail and wholesale.

M04 UnifrutCalzada 16 de Septiembre y M. JimenezApartado Postal 676Ciudad Cuauhtemoc, ChihuanuaMEXICOTelephones: (158) 2-00-95, (158) 2-00-41FAXes: (158) 2-01-21, (158) 2-06-41Retail and wholesale.

The two-spotted lady beetle,Adalia bipunctata, an aphidpredator. A, larva; B, pupa;C, adult

A CB

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UNITED STATES - Commercial Suppliers

U01 A-l Unique Insect Control5504 Sperry DriveCitrus Heights, CaliforniaU.S.A. 95621Telephone: (916) 961-7945FAX: (916) 967-7082Retail and wholesale. Free brochure. Formerly Unique Insect Control. A primary source of ladybugs.

U02 Agricultural Supply, Inc.1435 Simpson WayEscondido, CaliforniaU.S.A. 92029Telephones: (800) 527-6699, (619) 741-0066FAX: (619) 741-9412Retail and wholesale. Licensed Pest Control Advior’s available.

U03 American Insectaries, Inc.30805 Rodriguez RoadEscondido, CaliforniaU.S.A. 92026-5312Telephone: (619) 751-1436FAX: (619) 749-7061Retail and wholesale. Se habla Español. Wide variety of beneficial insects and mites available.

U04 Applied Bio-ControlP.O. Box 118Waterford, CaliforniaU.S.A. 95386Telephone: (209) 874-1862FAX: (209) 874-1808Retail and wholesale. Consultation service available both within and outside of California.

U05 ARBICO, Inc.P.O. Box 4247 CRBTucson, ArizonaU.S.A. 85738-1247Telephones: (602) 825-9785, (800) 827-2847FAX: (602) 825-2038Retail and wholesale. Free catalog and consulting

U06 Beneficial Insectary14751 Oak Run RoadOak Run, CaliforniaU.S.A. 96069Telephones: (800) 477-3715, (916) 472-3715FAX: (916) 472-3523Retail and wholesale. Producer and supplier. FREE literature, consulting, and training available.

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U07 Beneficial Insects Etc.P.O. Box 154Banta, CaliforniaU.S.A. 95304Telephone: (209) 835-6158Retail only. Lacewings April-July.

U08 Beneficial Ladybugs15010 Merchants Bar RoadMagalia, CaliforniaU.S.A. 95954Telephone: (916) 873-6729Wholesale only.

U09 Beneficial Resources Inc.P.O. Box 327Danville, PennsylvaniaU.S.A. 17821Telephones: (800) 268-4377, (717) 271-1741FAX: (717) 271-1187Retail and wholesale. Exclusive distributor of Biobest® beneficials and bumble bees.

U10 Bio-AgronomicsP.O. Box 1013Clovis, CaliforniaU.S.A. 93613Telephone: (209) 297-9288Retail and wholesale. Consulting services available. Information available on products and services.

U11 Bio AG Services4218 West MuscatFresno, CaliforniaU.S.A. 93706Telephone: (209) 268-2835Retail and wholesale. Biological control specialists.

U12 Bio AG Supply710 South ColumbiaPlainview, TexasU.S.A. 79072Telephones: (806) 293-5861, (800) 746-9900FAX: (806) 293-0712Retail and wholesale. Consulting. Food for beneficials. Price list.

U13 Bio-Control CompanyBox 337Berry Creek, CaliforniaU.S.A. 95916Telephone: (916) 589-5227Retail and wholesale. Free catalog available.

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U14 Binfac, Inc.P.O. Box 87Mathis, TexasU.S.A. 78368Telephone: (512) 547-3259FAX: (512) 547-9660Retail and wholesale. Complete advisory and consulting services within 400 miles or with substantial business.

U15 BioTactics, Inc.425 La Cadena Drive, West Unit #12Riverside, CaliforniaU.S.A. 92501Telephone: (909) 320-1366FAX: (909) 781 -6572Retail and wholesale. Mail order only. No retail store.

U16 Bo-Biotrol, Inc.9538 LupinWinton, CaliforniaU.S.A. 95388Telephones: (209) 358-1488 (800) 622-9045FAX: (209) 358-1127Retail and wholesale. Beneficials, consulting, and products for the home and farm. Free catalog available.

U17 Bountiful Gardens18001 Shafer Ranch RoadWillits, CaliforniaU.S.A. 95490Telephone: (707) 459-6410FAX: (707) 459-6410 (6-10 PM - PST)Retail only. Beneficials and other IPM materials. Also biointensive books and supplies.

U18 Bozeman Bio-TechP.O. Box 3146Bozeman, MontanaU.S.A. 59772Telephones: (800) 289-6656 (Orders only), (406) 587-5891 (Free consulting)FAX: (406) 587-0223Retail and wholesale. Free catalog and consulting.

U19 Buena BiosystemsP.O. Box 4008Ventura, CaliforniaU.S.A. 93007Telephones: (805) 525-2525, (805) 525-2526FAX: (805) 525-6058Retail and wholesale. International consulting. Se habla Español. IPM system design.

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U20 Bunting Biological North AmericaP.O. Box 2430Oxnard, CaliforniaU.S.A. 93034-2430Telephone: (805) 986-8265Wholesale only. Brochure on request.

U21 Burpee Seed Company300 Park AvenueWarminster, PennsylvaniaU.S.A. 18974Telephone: (215) 674-4900FAX: (805) 986-8267Retail and wholesale. Free catalog.

U22 CalTec Agri Marketing ServicesP.O. Box 576155Modesto, CaliforniaU.S.A. 95357Telephone: (800) 491 -2847Wholesale only.

U23 Central Coast Insectary391 Hames RoadWatsonville, CaliforniaU.S.A. 95076Telephone: (408) 726-1853FAX: (408) 726-5123Retail and wholesale. Producer. Se habla Español. Free guidebook for control of twospotted spider mites.

U24 CropKing Inc.P.O. Box 310Medina, OhioU.S.A. 44258Telephone: (216) 725-5656FAX: (216) 722-3958Retail and wholesale. Training and consulting. Free catalog.

U25 Cyline BioticP.O. Box 48Goodyears Bar, CalifomiaU.S.A. 95944-0048Telephone: (916)289-3122FAX: (916) 289-3122Retail and wholesale. Free brochure. Retail plan for nurseries. Ladybugs available all year long.

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U26 Down To Earth Distributors, Inc.345 Lincoln Street AlleyP.O. Box 1419Eugene, OregonU.S.A. 97440Telephone: (503) 485-5932FAX: (503) 485-7141Wholesale only.Call for free catalog of organic gardening supplies.

U27 FAR, Inc.510½ Chase DriveCorona, CaliforniaU.S.A. 91720Telephones: (909) 371-0120, (800) 640-2FAR (Central Valley)FAX: (909) 279-5150Retail and wholesale. Free literature.

U28 Gardener’s Supply Company.128 Intervale RoadBurlington, VermontU.S.A. 05401Telephone: (802) 863-1700FAX: (802) 660-4600Retail and wholesale. Mail order catalog. Free catalog and free gardening consultation.

U29 Gardens Alive!5100 Schenley PlaceLawrenceburg, IndianaU.S.A. 47025Telephone: (812) 537-8650FAX: (812) 537-5108Retail only. Free catalog.

U30 Garden-Ville of Austin8648 Old Bee Caves RoadAustin, TexasU.S.A. 78735Telephone: (512) 288-6115FAX: (512) 288-6114Retail only. Call, write or FAX for free catalog. USA and Canada only.

U31 Great Lakes IPM10220 Church Road NEVestaburg, MichiganU.S.A. 48891Telephone: (517) 268-5693 or (517) 268-5911FAX: (517) 268-5311Retail only.

115

U32 Greenfire Inc.347 Nord Avenue #1Chico, CaliforniaU.S.A. 95926Telephone: (916) 895-8301FAX: (916) 895-8317Retail only. Free catalog.

U33 Gurney Seed & Nursery Company110 Capital StreetYankton, South DakotaU.S.A. 57079Telephone: (605) 665-1930Retail only. Free catalog.

U34 Harmony Farm SupplyP.O. Box 460Graton, CaliforniaU.S.A. 95444Telephone: (707) 823 -9125FAX: (707) 823-1734Retail only. Send $2 for catalog (refunded with 1st order). Consulting available.

U35 Helena Chemical Company2589 North Air-Fresno Dr. #105Fresno, CaliforniaU.S.A. 93727Telephone: (209) 453-9385FAX: (209) 453-0655Retail and wholesale. IPM consulting available.

U36 Henry Field’s Seed & Nursery Co.415 North Bumett StreetShenandoah, lowaU.S.A. 51602Telephone: (605) 665-4491Retail only. Free catalog.

U37 Hydro-Gardens, Inc.P.O. Box 25845Colorado Springs, ColoradoU.S.A. 80936Telephones/FAXes: (719) 495-2266, (800) 634-6362Retail and wholesale. Free catalog. Dealers welcome. Complete greenhouse supplies.

U38 IFM - Integrated Fertility Mgmt.333 Ohme Gardens RoadWenatchee, WashingtonU.S.A. 98801Telephones: (509) 662-3179, (800) 332-3179Retail and wholesale. Free catalog.

116

U39 Integrated Pest Management ServicesP.O. Box 989Fresno, CaliforniaU.S.A. 93714Telephones: (209) 456-0990, (209) 284-1538 (Cellular phone)FAX: (209) 456-1156Retail and wholesale.

U40 IPM Laboratories, Inc.Main StreetLocke, New YorkU.S.A. 13092-0300Telephone: (315) 497-2063FAX: (315) 497-3129Retail and wholesale. Free catalogs. Specialties: greenhouses, nurseries and NE U.S.A. manure fly control.

U41 Koppert USAP.O. Box 39387North Ridgeville, OhioU.S.A. 44039Telephone: (216) 353-9437FAX: (216) 353-9457Retail and wholesale.

U42 Kunafin InsectaryRoute 1, Box 39Quemado, TexasU.S.A. 78877Telephones: (210) 757-1181, (800) 832-1113FAX: (210) 757-1468Retail and wholesale. Consulting entomologists. Se habla Español. German also spoken. We mass rearbeneficials.

U43 Ladybug SalesP.O. Box 903Gridley, CaliforniaU.S.A. 95948-0903Telephones: (916) 846-9907FAX: (916) 846-2655Retail and wholesale. Pest control consulting and co-ordination services.

U44 Mellinger’s, Inc.2310 West South Range RoadNorth Lima, OhioU.S.A. 44452Telephones: (216) 549-9861, (800) 321-7444 (orders/catalog)FAX: (216) 549-3716Retail only. Free catalog.

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U45 M & R Durango, Inc.P.O. Box 886Bayfield, ColoradoU.S.A. 81122Telephones: (303) 259-3521, (800) 526-4075FAX: (303) 259-3857Retail and wholesale. Producer. Free brochure. Technical support and consultation available.

U46 Natural Pest Controls8864 Little Creek DriveOrangevale, CaliforniaU.S.A. 95662Telephone: (916) 726-0855FAX: (916) 726-0855Retail and wholesale. Please send self addressed stamped envelope for free catalog. Packing for retailers.

U47 Nature’s ControlP.O. Box 35Medford, OregonU.S.A. 97501Telephone: (503) 899-8318FAXes: (800) 698-6250 (U.S.A.), (503) 899-9121Retail and wholesale. Free brochure. Credit cards and COD orders are accepted.

U48 Necessary Trading CompanyP.O. Box 603New Castle, VirginiaU.S.A. 24127Telephone: (703) 864-5103FAX: (703) 864-5186Retail only. Write for free catalog.

U49 New Earth, Inc.3623 East Highway 44Shepherdsville, KentuckyU.S.A. 40165Telephone: (502) 543-5933

U50 Oxnard Pest Control Association666 Pacific AvenueP.O. Box 1187Oxnard, CaliforniaU.S.A. 93032Telephone: (805) 483-1024FAX: (805) 487-6867Retail and wholesale. Producer of Cryptolaemus. Available year round.

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U51 Pacific Tree Farms4301 Lynwood DriveChula Vista, CaliforniaU.S.A. 91910Telephone: (619) 422-2400Retail and wholesale. Our nursery specializes in new and rare plants and trees.

U52 Peaceful Valley Farm SupplyP.O. Box 2209Grass Valley, CaliforniaU.S.A. 95945Telephone: (916) 272-4769FAX: (916) 272-4794Retail only. Free 125 page catalog of organic and IPM supplies.

U53 Pest Management Supply, Inc.311 River DriveHadley, MassachusettsU.S.A. 01035Telephones: (413) 549-7246, (800) 272-7672 (U.S.A. & CAN)FAX: (413) 549-3930Retail and wholesale. Phone, FAX and mail ordering with MC, VISA, purchase orders, or checks accepted.

U54 Plant Sciences, Inc. (Koppert)342 Green Valley RoadWatsonville, CaliforniaU.S.A. 95076Telephone: (408) 728-7771FAX: (408) 728-4967Retail and wholesale. All FAXed orders will receive a FAXed confirmation.

U55 Praxis2723 116th AvenueAllegan, MichiganU.S.A. 49010Telephone: (616) 673-2793FAX: (616) 673-2793Wholesale only. We sell site specific Biotool-kits

U56 Rincon-Vitova Insectaries Inc.P O Box 1555Ventura, CaliforniaU.S.A. 93002Telephone: (805) 643-5407FAX: (805) 643-6267Retail and wholesale. Price list and technical bulletins.

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U57 San Jacinto Environmental Supplies2221-A West 34th StreetHouston, TexasU.S.A. 77018Telephone: (713) 957-0909FAX: (713) 957-0707Wholesale only. Free catalog. Complete supplies. Manufacturers of organic fertilizers.

U58 Sierra Ag2749 East MalagaFresno, CaliforniaU.S A. 93725Telephone: (209) 233-0585FAX: (209) 233-0633Retail and wholesale.We are able to handle and service large acreage.

U59 Spalding Laboratories760 Printz RoadArroyo Grande, CaliforniaU.S.A. 93420Telephones: (805) 489-5946, (800) 845-2847 (BUGS)Retail only. Free brochure.

U60 Stanley GardensP.O.Box913Belchertown, MassachusettsU.S.A. 01007-0913Telephone: (413) 323-6196FAX: (413) 323-9594Retail and wholesale. Only sell beneficials reared in-house. IPM consulting available within 100 miles.

U61 Sweetbriar Development, Inc.1767 San Juan RoadWatsonville, CaliforniaU.S.A. 95076Telephones: (408) 722-5577, (408) 332-4559, (408) 722-0215FAX: (408) 722-0191Retail and wholesale. Brochure available. Se habla Español.

U62 Territorial Seed CompanyP.O. Box 157Cottage Grove, OregonU.S.A. 97424Telephone: (503) 942-9547FAX: (503) 942-9881Retail and wholesale. Write, FAX, or phone for free catalog.

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U63 The Beneficial Insect Company244 Forrest StreetFort Mill, South CarolinaU.S.A. 29715Telephone: (803) 547-2301Retail and wholesale. Catalog available. Supplying beneficial organisms to southeastern growers since1987.

U64 The Green SpotDepartment of Bio-Ingenuity93 Priest RoadBarrington, New HampshireU.S.A. 03825Telephone: (603) 942-8925Retail and wholesale. Free informative catalog. Free telephone consultation.

U65 Tri-Cal BiosystemsP.O. Box 1327Hollister, CaliforniaU.S.A. 95024Telephone: (408) 637-0195 (909) 737-6960 (Español)FAX: (408) 637-0273Retail only. Se habla español. Permits for all U.S.A. states and Mexico.

U66 Visalia Insectary Inc.P.O. Box 3205Visalia. CaliforniaU.S.A. 93278Telephones: (209) 731-8787, (209) 732-6249FAX: (209) 732-6249Retail and wholesale. Predators available on bean leaves, delivery arranged, or bottled in corn grits.

U67 Worm’s Way Inc.3151 South Highway 446Bloomington, IndianaU.S.A. 47401Telephone: (800) 274-9676 (IN), (800) 283-9676 (FL), (800) 284-9676 (MA)FAX: (812) 331-0854Retail only. Free 4-color catalog of organic and hydroponic gardening supplies, and natural pest controls.

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Parasites and Predators for Greenhouse Pests

Adalia bipunctata - twospotted lady beetle, a predator for aphids - U28Aphelinus abdominalis - a parasite for aphids - C05, U24, U40, U41, U54Aphidoletes aphidimyza - a predator for aphids - C01, C02, C04, C05, C06, C07, C09, C10, U03, U05, U09, U18,

U19, U22, U24, U31, U32, U34, U37, U38, U39, U40, U41, U45, U46, U47, U48, U52, U54, U55, U56,U64, U65, U67

Aphidius colemani - a parasite for aphids - C05, U20, U31, U40, U41, U54Aphidius matricariae - a parasite for aphids - C01, C04, C07, C10, U09, U24, U27, U31, U34, U37, U38, U39, U45,

U47, U54, U55, U56, U64, U65Cryptolaemus montrouzieri - mealy bug destroyer, a predator for various scales and mealybugs - C03, C04, C05,

C06, C07, C09, C10, U01, U03, U05, U09, U10, U11, U12, U16, U18, U19, U20, U22, U24, U27,U34, U35, U37, U38, U39, U40, U41, U44, U45, U47, U50, U52, U54, U55, U56, U57, U58, U63, U64,U65, U67

Dacnusa sibirica - a parasite for leafminers - C05, C07, U09, U19, U20, U22, U24, U37, U39, U41, U46, U54, U55,U64

Delphastus pusillus - a predator for whiteflies - C01, C04, C05, C07, C10, U03, U05, U09, U12, U15, U18, U19,U24, U34, U37, U38, U39, U40, U41, U53, U54, U55, U56, U57, U60, U63, U64

Delphastus spp. - predators for whiteflies - C07, U39, U55, U64Diaeretiella rapae - a parasite for aphids - C06, C07, U03, U39, U55Diglyphus isaea - a parasite for leafminers - C05, C06, C07, U05, U09, U10, U19, U20, U22, U24, U34, U35, U37,

U38, U39, U41, U46, U54, U55, U64Encarsia desert) (=luteola) - a parasite for whiteflies - U03Encarsia formosa - a greenhouse whitefly parasite - C01, C02, C04, C05, C06, C07, C08, C09, C10, U01, U02,

U03, U05, U09, U10, U12, U14, U16, U18, U19, U20, U22, U24, U27, U29, U30, U32, U34, U35, U37,U38, U39, U40, U41, U44, U45, U46, U47, U48, U52, U53, U54, U55, U56, U57, U58, U63, U64, U65,U67

Encarsia spp. - parasites for whiteflies - C07, U02, U03, U09, U15, U16, U39, U46, U55, U64Eretmocerus californicus - a parasite for sweet potato whitefly - U40Eretmocerus spp. - a parasite for whiteflies - C05, U05, U09, U20, U39, U41, U45, U55Hippodamia convergens - convergent lady beetle, a general predator - C02, C04, C05, C06, C07, C09, C10, U01,

U02, U03, U05, U08, U09, U10, U12, U13, U14, U18, U19, U21, U22, U24, U25, U26, U29, U30, U32,U33, U34, U35, U36, U37, U38, U39, U40, U43, U44, U45, U46, U47, U48, U49, U52, U54, U55, U56,U62, U63, U64, U67

Hypoaspis (=Stratiolaelaps) miles - a predatory mite for fungus gnats and flower thrips - C01, C06, C07, C10, U03,U05, U09, U19, U34, U37, U38, U40, U45, U54, U55, U56, U63, U64, U65

Iphiseius (=Amblyseius) degenerans - a predatory mite for western flower thrips and pest mites - U09, U15, U24,U40, U41, U54, U64

Lysiphlebus testaceipes - a parasite for aphids - U03, U12, U39, U55Orius insidiosus - a general predator - C07, U40, U64, U67Orius tristicolor - minute pirate bug, a general predator - C06, C07, U03, U10, U12, U22, U35, U39, U47, U55Orius spp. - a general predator - C05, C07, U05, U06, U09.U12, U14, U16, U18, U19, U20,U24, U34, U37, U38,

U39, U41, U45, U52, U54, U55, U56, U57, U65

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Scolothrips sexmaculatus - sixspotted thrips, a predator for mites and thrips - U39Thripobius semiluteus - a parasite for thrips - C04, C07, U03, U05, U19, U22, U27, U38, U39, U40, U47, U52,

U55, U64, U67

Scale and Mealybug Parasites and Predators

Aphytis melinus - a parasite for red scale - C02, C05, C06, C07, U02, U03, U05, U09, U10, U11, U12, U16,U19, U22, U27, U31, U34, U35, U37, U38, U39, U40, U45, U46, U52, U55, U56, U58, U64

Chilocorus kuwanae - a predator for euonymus scale - U55Chilocorus nigritus - a predator for various scales - U55Cryptolaemus montrouzieri - mealy bug destroyer, a predator for various scales and mealybugs - C03, C04, C05,

C06, C07, C09, C10, U01, U03, U05, U09, U10, U11, U12, U16, U18, U19, U20, U22, U24, U27,U34, U35, U37, U38, U39, U40, U41, U44, U45, U47, U50, U52, U54, U55, U56, U57, U58, U63, U64,U65, U67

Leptomastix dactylopii - a parasite for citrus mealybug - C03, C04, C05, C07, C08, C10, U12, U19, U24, U38, U40,U41, U55, U56, U64

Metaphycus helvolus - a parasite for black scale - C02, C06, C07, C10, U03, U05, U10, U19, U34, U38, U40,U45, U46, U52, U55, U56, U64

Microterys nietneri (=flavus) - a parasite for brown scale -U46, U55Rhycobius (=Lindorus) lophanthae - a predator for various scales - C03, C04, C05, C07, U18, U34, U37, U38,

U40, U55, U56, U64

Aphid Parasites and Predators

Adalia bipunclata - twospotted lady beetle, a predator - U28Aphelinus abdominalis - a parasite - C05, U24, U40, U41, U54Aphidoletes aphidimyza - a predator - C01, C02, C04, C05, C06, C07, C09, C10, U03, U05, U09, U18, U19, U22,

U24, U31, U32, U34, U37, U38, U39, U40, U41, U45, U46, U47, U48, U52, U54, U55, U56, U64, U65,U67

Aphidius colemani - a parasite - C05, U20, U31, U40, U41, U54Aphidius matricariae - a parasite - C01, C04, C07, C10, U09, U24, U27, U31, U34, U37, U38, U39, U45, U47, U54,

U55, U56, U64, U65Chrysoperla (=Chrysopa) carnea - common green lacewing, a predator - C02, C04, C05, C06, C07, C09, C10,

M03, U02, U03, U05, U09, U10, U12, U16, U19, U22, U24, U27, U29, U30, U31, U34, U37, U38, U39,U42, U44, U46, U48, U52, U55, U56, U57, U58, U64, U65, U67

Chrysoperla (=Chrysopa) comanche - Comanche lacewing, a predator - U10, U11, U12, U16, U19, U22, U34,U38, U39, U46, U55, U56, U57, U58, U64, U65

Chrysoperla (= Chrysopa) rufilabris - a green lacewing, a predator - C02, C06, C07, U03, U05, U06, U10, U12,U14.U16, U17, U18, U19, U20, U22, U29, U34, U37, U38, U39, U40, U42, U45, U46, U47, U52, U55,U56, U57, U58, U62, U63, U64, U65, U67

Chrysoperla & Chrysopa spp. - green lacewings, predators - C07, M01, M02, M04, U01, U04, U06, U07, U12,U13, U16, U21, U32, U33, U35, U36, U38, U39, U46, U55, U57, U58, U64, U65

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Coccinella septempunctata - sevenspotted lady beetle, a predator - U29Deraeocoris brevis - a true bug, a predator - C01, U56, U64Diaeretiella rapae - a parasite - C06, C07, U03, U39, U55Hippodamia convergens - convergent lady beetle, a predator - C02, C04, C05, C06, C07, C09, C10, U01, U02, U03,

U05, U08, U09, U10, U12, U13, U14, U18, U19, U21, U22, U24vU25, U26, U29, U30, U32, U33, U34,U35, U36, U37, U38, U39, U40, U43, U44, U45, U46, U47, U48, U49, U52, U54, U55, U56, U62, U63,U64, U67

Lysiphlebus testaceipes - a parasite - U03, U12, U39, U55Macrolophus caliginosus - a predator - C05, U09, U41, U54Orius insidiosus - a predator - C07, U40, U64, U67Orius tristicolor - minute pirate bug, a predator - C06, C07, U03, U10, U12, U22, U35, U39, U47, U55Orius spp. - a predator - C05, C07, U05, U06, U09, U12, U14, U16, U18, U19, U20, U24, U34, U37, U38, U39,

U41, U45, U52, U54, U55, U56, U57, U65

Whitefly Parasites and Predators

Chrysoperla (=Chrysopa) carnea - common green lacewing, a predator - C02, C04, C05, C06, C07, C09, C10,M03, U02, U03, U05, U09, U10, U12, U16, U19, U22, U24, U27, U29, U30, U31, U34, U37, U38, U39,U42, U44, U46, U48, U52, U55, U56, U57, U58, U64, U65, U67

Chrysoperla (=Chrysopa) comanche - Comanche lacewing, a predator - U10, U11, U12, U16, U19, U22, U34,U38, U39, U46, U55, U56, U57, U58, U64, U65

Chrysoperla (=Chrysopa) rufilabris - a green lacewing, a predator - C02, C06, C07, U03, U05, U06, U10, U12,U14, U16, U17, U18, U19, U20, U22, U29, U34, U37, U38, U39, U40, U42, U45, U46, U47, U52, U55,U56, U57, U58, U62, U63, U64, U65, U67

Chrysoperla & Chrysopa spp. - green lacewings, predators - C07, M01, M02, M04, U01, U04, U06, U07, U12,U13, U16, U21, U32, U33, U35, U36, U38, U39, U46, U55, U57, U58, U64, U65

Delphastus pusillus - a predator for sweet potato whitefly - C01, C04, C05, C07, C10, U03, U05, U09, U12, U15,U18, U19, U24, U34, U37, U38, U39, U40, U41, U53, U54, U55, U56, U57, U60, U63, U64

Delphastus spp. - predators - C07, U39, U55, U64Deraeocoris brevis - a true bug, a predator - C0 1, U56, U64Encarsia deserti (=luteola) - a parasite for sweet potato whitefly - U03Encarsia formosa - a parasite for greenhouse whitefly - C01, C02, C04, C05, C06, C07, C08, C09, C10, U01, U02,

U03, U05, U09, U10, U12, U14, U16, U18, U19, U20, U22, U24, U27, U29, U30, U32, U34, U35, U37,U38, U39, U40, U41, U44, U45, U46, U47, U48, U52, U53, U54, U55, U56, U57, U58, U63, U64, U65,U67

Encarsia spp. - parasites - C07, U02, U03, U09, U15, U16, U39, U46, U55, U64Eretmocerus californicus - a parasite for sweet potato whitefly - U40Eretmocerus spp. - parasites - C05, U05, U09, U20, U39, U41, U45, U55Macrolophus caliginosus - a predator - C05, U09, U41, U54

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Predatory Mites

Galendromus annectans - for pest mites - U03, U15, U19Galendromus (=Metaseiulus, =Typhlodromus) occidentalis - western predatory mite for spider mites - C01, C04,

C05, C06, C07, C10, U01, U03, U05, U06, U10, U11, U12, U15, U16, U18, U19, U22, U23, U27, U32,U34, U35, U37, U38, U39, U40, U41, U44, U45, U46, U47, U51, U52, U54, U55, U56, U57, U58, U63,U64, U65, U66

Hypoaspis (=Stratiolaelaps) miles - for fungus gnats and flower thrips - C01, C06, C07, C10, U03, U05, U09, U19,U34, U37, U38, U40, U45, U54, U55, U56, U63, U64, U65

Iphiseius (=Amblyseius) degenerans - for western flower thrips and pest mites - U09, U15, U24, U40, U41, U54,U64

Mesoseiulus (= Phytoseiulus) longipes - for spider mites - C07, C10, U03, U05, U10, U12, U15, U18, U27, U29,U32, U34, U37, U38, U40, U46, U47, U48, U51, U52, U55, U56, U63, U64, U65, U67

Neoseiulus (=Amblyseius, =Phytoseiulus) barkeri (=mckenziei) - for thrips - C06, C07, U03, U05, U24, U27, U37,U40, U45, U46, U53, U55, U57, U63, U65

Neoseiulus (=Amblyseius) californicus - for spider mites - C05, C06, C07, C10, U01, U03, U05, U06, U10, U12,U15, U18, U22, U27, U29, U31, U32, U34, U35, U37, U38, U40, U46, U47, U48, U51, U52, U53, U55,U56, U57, U57, U63, U64, U65, U67

Neoseiulus (=Amblyseius) cucumeris - for thrips, cyclamen and broad mites - C01, C02, C04, C05, C06, C07, C08,C09, C10, U03, U05, U09, U16, U18, U19, U20, U22, U24, U31, U32, U34, U35, U37, U38, U40, U41,U45, U46, U47, U48, U51, U52, U53, U54, U55, U56, U57, U63, U64, U65

Neoseiulus (=Amblyseius) fallacis - for European red and twospotted spider mites - C01, C07, C10, U11, U12,U31, U40, U53, U55, U56, U60, U63, U64, U65

Phytoseiulus macropilis - for spider mites - U15, U40Phytoseiulus persimilis - for spider mites - C01, C02, C04, C05, C06, C07, C08, C09, C10, U01, U02, U03, U05,

U06, U09, U10, U11, U12, U14, U15, U16, U18, U19, U20, U22, U23, U24, U27, U29, U31, U32, U34,U35, U37, U38, U39, U40, U41, U45, U46, U47, U48, U52, U53, U54, U55, U56, U58, U61, U63, U64,U65, U67

Various species of predatory mites - U04, U49

Aphidius testaceipes, a braconid wasp parasite of aphids

125

ANSWERS TO REVIEW QUESTIONS

APPENDIX C

Section 1

1. True2. d3. True4. biological, cultural, mechanical5. True6. True7. d8. True

Section 2

1. True2. True3. d4. False5. take down hanging plants before treatment, do

not use highly toxic pesticides in hanging bas-kets, only treat overhead plants in the next aislenot directly above you, apply the pesticide whilebacking away and use the least toxic methodsavailable

6. False7. False8. they are unaware of the routine hazards inside

greenhouses9. d10. by establishing a totally separate display and

sales area where no pesticides are applied11. False

Section 3

1. False2. temperature, humidity, ventilation, heating sys-

tems and volatilization3. True4. d5. an irrigation water containment and recycling

system, prevents escape of pesticides and nutri-ents from the greenhouse.

6. c7. False8. b9. True

Section 4

1. scouting, pest identification, timing treatmentsand record keeping

2. b3. False

4.5. False6. d7. True8. c9. b

126

10. True11. Sanitation12. To reduce insect, weed and disease pest

reinfestation13. False14. a15. screens, vacuuming, pruning and roging16. False17. False18. d19. b20. nonspecific, broad mode of action

Section 5

1. True2. False3. c4. True5. False

Section 6

1. d2. True3. False4. b5. True6. False7. c8. True9. False10. False11. d

Section 7

1. True2. False3. chloropicrin, Vorlex, Vapam, Telone and

Basamid4. a & c5. False6. True7. c

Section 8

1. b & c2. True3. b4. False5. d6. gradual change in light intensity and duration of

light7. d8. c9. True10. True11. c12. False13. Botrytis & Chrysanthemum leafminers14. b15. False16. False17. True18. d

Section 9

1. True2. b3. False4. a5. False6. d7. True8. True9. c10. True11. True12. b13. True14. b15. d16. False17. True18. undersides of leaves19. True20. d21. True

127

22. True23. d24. b25. True26. True27. a & c28. b29. True30. True31. False32. a33. False34. cube of potato tuber on the soil35. True36. True

Section 10

1. d2. True3. True4. False5. c6. True7. True8. b9. False10. d11. False12. True13. adequate air circulation, relative humidity be-

low 90%, don’t over crowd plants, remove deador diseased plant material, don’t leave large stubsor joints and remove senescent flowers

14. b15. True16. True17. b18. True19. d20. d21. True22. See pages 91 and 9223. False24. c

25. False26. False27. See pages 93 and 94

Section 11

1. True2. True3. mowing, herbicide application, mulches, steam

pasteurization, fumigation and hand weeding4. True5. d6. False7. True8. improved horizontal air flow, sanitation (clean-

ing benches), ground cover fabrics