considering canna bis - ball publishing...mind and a curiosity to explore the cannabis industry...

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FROM FOOTBALLTO FARMING Ayoung man's journeyinto hydroponics

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FIELD-GROWNLETTUCE Whichones work inhydroponic systems?

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GROWINGORGANIC? Theseare the best fertilizers

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October 2015 CONTROLLED ENV I RONMENT AGR ICULTURE

ConsideringCannabis THE SCIENCE ANDPRACTICALITY OFGROWING CEA’STRENDIEST CROP.WILL YOU BECAUGHT UP IN THE“GREEN RUSH”?0

Reader Service Number 200

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Whether you’re morally for or against the use ofcannabis products, it’s one of the fastest-growing indus-tries in the U.S. and it’s increasing impact on the horti-culture industry is undeniable. As more states legalize itscultivation for medicinal use (or even recreational use)and decriminalize its possession, the once-taboo cropisn’t raising as many eyebrows. The so-called “greenrush” is providing jobs for skilled growers and boostingbusiness for greenhouse manufacturers and growingsuppliers.

All that said, we decided to put cannabis cultivationin the spotlight for this issue’s cover story. This isn’t the

first time we’ve broken from the mold andpushed the boundaries of the traditional hor-ticulture industry. In June 2011, GrowerTalkswas the first trade publication in our industryto openly discuss cannabis—a feature storyManaging Editor Jennifer Zurko won a presti-gious national award for.

Four years later, cannabis cultivation ismore widespread and the topic is less likelyto ruffle as many feathers—we think.

Not knowing exactly where this storywould take me, I set out with simply an openmind and a curiosity to explore the cannabisindustry objectively and try to answer somequestions I thought my readers would be cu-rious about.

Naturally, I began my journey to learnmore about the industry in Burlington, Ver-mont, the place I call home. Vermont has asmall, but tightly regulated, medical cannabisprogram and it’s possible the state legislaturewill legalize the recreational use of mari-juana in 2016. I interviewed several growersand a dispensary owner here in Vermont andreached out to other growers, consultantsand suppliers throughout the country. The re-sult is a straightforward and unprejudicedlook at some of the opportunities and chal-lenges of cultivating cannabis in today’s in-dustry. Read all about it on page 10.

Of course, this issue of Inside Grower isalso packed full of the practical informationyou’ve come to expect. You’ll learn moreabout biocontrols for tomato plants (a.k.a.the “bug-eat-bug” approach); managingpythium in hydroponics; field lettuce vari-eties that also perform great in the green-

house; organic fertilizers and much more.We hope you enjoy this publication of Inside Grower.

As always, we welcome your questions and feedback.

issue of Inside Grower four years ago, we’vemaintained a focus on the cultivation of ediblecrops in controlled environments—and we’llcontinue to do so moving forward. Althoughit’s rarely discussed in traditional horticulture,

we all know that much of the same technologyand techniques used in indoor production of

tomatoes and leafy greens (and evenornamentals) are also used in the cultivation

of cannabis, a.k.a. marijuana.

Since sending out the first

Annie WhiteMANAGING EDITORfeedback: [email protected]

From Your Editor

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EDITORIAL EDITOR Chris Beytes MANAGING EDITOR Jennifer Zurko CONTRIBUTING EDITORS Annie White Jennifer Duffield White CONTRIBUTING WRITERS Anne-Marie Hardie David Kuack Neil Mattson PRODUCTION MANAGER Kathy Wootton CREATIVE DIRECTOR Chris Truesdale PHOTOGRAPHER Mark Widhalm COPY EDITOR Sue Olsen

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DEPARTMENTS 4 | From Your Editor6 | Insider

31 | New Products

FEATURES 10 | Considering Cannabis | by Annie White, Photos by Michael Tallman

The science and practicality of growing CEA’s trendiest crop.

16 | Lettuce Tell You What to Grow | by David KuackUniversity of Arkansas researchers trialed 65 lettuce varieties to determine theirpotential for production in greenhouse hydroponic systems.

20 | Growing Greenhouse Tomatoes in Containers | by Neil MattsonA good way to jump into producing finished greenhouse vegetables from beddingplants is to grow tomatoes.

24 | From Football to Farming | by Anne-Marie HardieA young go-getter turned his love for horticulture into a career with a strong futurein hydroponics.

26 | Thoughts on Using Organic Fertilizers for GreenhousePlants | by Douglas Cox Growing organic? Here are your best choices.

28 | Biocontrols for Tomato Plants | by Scott CrearyThe best parasitic weapons to use to defend your tomato crops.

32 | Hydroponic Production & Pythium | by Helen Margaret Griffiths You can still experience root rot even when you’re not growing in soil. Learningthe symptoms and how to prevent Pythium can be a crop lifesaver.

CONTROLLED ENVIRONMENT AGRICULTURE

October 2015

ON THE COVERAs more states legalize its cultivation for medicinaluse (or even recreational use) and decriminalize

its possession, one of the fastest-growingindustries in the United States isn’t raising asmany eyebrows, even in our traditionally more

conservative horticulture industry. Turn to page 10 to read more.

Photo by Michael Tallman.

New York Greenhouse Project toCreate 100 Labs for Kids by 2020Started in 2008 by a small group of public school parents and educa-tors, The Greenhouse Project continues to work towards their ambitious

goal of having 100 greenhouse project classrooms built by the year 2020.Originally inspired by New York Sun Works Science Barge, the proj-

ect’s founders believe that urban farms on school rooftops in the NewYork City area can serve as highly influential classrooms.

To date, 26 greenhouse project classrooms have been created at localschools by the non-profit New York Sun Works. Fifteen more localschools will be getting greenhouse project classrooms during thisschool year. The program is aiming to have 100 built by 2020.

Most of the greenhouse project classrooms are built as traditionalgreenhouses to accommodate a hydroponic urban farm and environ-mental science laboratory. They typically include solar panels, hydro-ponic growing systems, a rainwater catchment system, a weather stationand a vermicomposting station.

Grade school children grow food while learning hands-on about nu-trition, water resource management, efficient land use, climate change,biodiversity, conservation, contamination, pollution, waste managementand sustainable development. The laboratory operates as an integratedpart of the school’s curricula.

In addition to enhancing a school’s science curriculum, the green-house laboratory greatly enriches arts and social studies by connectingnature to culture. Students learn the relationship between humans andthe environment, and gain a greater appreciation of sustainable develop-ment and its direct relationship to cultural diversity.

Want to help support this effort to connect urban kids with green-

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Insider

Move Over Jell-O, Hospitals areGrowing Veggies by the AcreMore and more hospitals, once known for their abundance of Jell-O fla-vors and soggy fries, are tearing out the deep fryers and partnering withlocal farms to give their cafeteria menus healthful makeovers. Some hos-

pitals are even starting their own farms.Jodi Helmer at civileats.com recently high-lighted two hospitals that are farming in

earnest, greenhouses and all.Joining the staff of medical pro-

fessionals at St. Joseph Mercy in Ypsilanti, Michigan, is Dan Bair, afull-time farmer. He manages about

25 acres of arable farmland (previouslylawn) and three 30 ft. x 96 ft. hoophouses

on the hospital’s campus. All year round, Danand his farm volunteers grow fresh produce tosell at the hospital’s farmers’ market and to in-clude in patient meals. You can visit their web-site at www.stjoesannarbor.org/thefarm. At St. Luke’s Hospital in Bethlehem, Pennsylvania,

new moms are sent home from the hospital with a bas-ket of fresh organic produce grown just outside on the

hospital’s own farm. Started last year, the farm doubled insize this year, expanding to 10 acres and 30 varieties of fruits and vegetables.

St. Luke’s partnered with the Rodale Institute to make their farmingdreams come to fruition. The non-profit, organic farming gurus helpedplan and design the farm, hire a farmer and manage operations.

Sounds great, right? Well, the unfortunate reality is that growing or-ganic produce on a small on-site farm is more expensive for the hospi-tals than purchasing it through a food service supplier or sourcing itlocally from other farms. According to Jodi’s article, it took a $125,000 ofcapital investment to start the farm at St. Luke’s, and after two growingseasons, the farm is operating at a loss. They hope to break even in 2016.

Most Americans Could be Fed Entirely by Local FoodNew research shows that more than 90% of Americans could be fed en-tirely by food grown or raised within 100 miles of their homes.

The research, led by University of California—Merced Professor El-liott Campbell, used farmland mapping data and land productivity infor-mation to compare the potential calorie production of existing farms tothe population of American cities. Studying the farms and populationwithin a local radius, they were able to determine what percentage ofthe population could be supported entirely by food grown locally.

The researchers found surprising potential in major coastal cities. Forexample, New York City could feed only 5% of its population within 50miles, but could feed as much as 30% within 100 miles. The greater LosAngeles area could feed as much as 50% within 100 miles.

More people could eat entirely locally if they switched to a plant-based diet. For example, local food around San Diego can support 35%of the people based on the average U.S. diet, but as much as 51% of thepopulation if people switched to plant-based diets.

The popularity of “farm to table” has skyrocketed in the past few yearsas people become more interested in supporting local farmers, but El-liot’s research suggests that there’s enough farmland that eating locally

doesn’t have to be a passing fad. However, as hismaps suggest, careful planning and policies areneeded to protect farmland from suburbanizationand development.

The research didn’t specificallylook at greenhouse farming as an

option to grow more food locally, especially in urban areas.

You can find andpurchase the full re-search paper in theJune 2015 peer-re-viewed publicationFrontiers in Ecology and the Environment.

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P. Allen Smith toPromote SakataVegetable SeedBrandSakata Seed America has an-

nounced a new partnershipbetween the company’sHome Grown Vegetable di-vision and P. Allen SmithGarden Home. Sakata

Home Grown is now the offi-cial vegetable seed brand of P. AllenSmith. Furthermore, P. Allen hasidentified a collection of Sakata varieties and branded it under the P. Allen Smith Home Grown SeedCollection.

P. Allen is an award-winning de-signer, gardener and lifestyle expert.His television programs, “GardenHome,” “Garden to Table,” and “Gar-den Style,” air on hundreds of sta-tions nationally.

“A return to the vegetable gar-den is a welcomed trend, which isgood for the well-being of our-selves, families and communities,”says P. Allen. “It may not be possibleto grow an entire garden, but grow-ing just a few things makes a difference.”

Sakata Marketing Manager Ale-cia Troy says the company looks for-ward to the exposure P. Allen willbring to gardening and healthy eat-ing with the P. Allen Smith HomeGrown Seed Collection.

“Our partnership with P. AllenSmith is an exciting step towardconnecting with consumersthrough education and passion,”adds Alecia.

P. Allen Smith also has partner-ships with Bonnie Plants, ProvenWinners, Jobes Organics and LeCreuset.

LumiGrow Offers New Lighting Control SystemLumiGrow, Inc., a California-based leader in greenhouse spectrum control systems, recently introduced whatthey’re calling the most advanced lighting control system in horticulture.

It’s called SmartPAR and it offers growers the same kind of control over the light environment as theyhave over most other parts of the greenhouse and indoor growing environments.

“We know our customers need every advantage they can get to maximize yields without increasing thesize or expense of their operation,” said Kevin Wells, CEO at LumiGrow. “The SmartPAR system is the next stepin helping LumiGrow customers do just that.”

The patented system’s software and hardwarework together to offer complete spectrum con-trol, allowing growers to target plants with thekind of light they need when they need it.

LumiGrow says SmartPAR can be used to:l Create separate lighting zones to differentiate production areasl Remotely control the spectral output of zones to improve crop yield, productivity and energy efficiencyl Monitor the lighting system using real-time feedback for fixture maintenance and facility managementl Adjust light levels as needed when crop needs and available sunlight changes

Fresh Produce Reaching More Low-Income FamiliesA sharp increase in Supplemental Nutrition Assistance Program (SNAP) benefit redemptions through farm-ers and farmers markets suggests more fresh produce is reaching low-income families in the U.S.

SNAP participants spent $18.8 million of their benefits (also known as “food stamps”) last year at road-side farm stands, farmers markets and directly from local farmers. That’s a six-fold increase since 2008. Thereare also eight times as many SNAP-authorized farmers now (over 6,400 vendors) than in 2008 (753 vendors).USDA provides free wireless equipment to qualifying farmers and farmers markets, enabling them to acceptSNAP via electronic benefit transfers (EBT).

Additionally, in May, USDA announced the availability of $3.3 million in Farmers Market SNAP SupportGrants to help farmers markets serve SNAP participants.

USDA also recently awarded $31.5 million in funding to local, state and national organizations to support

New “Sticky Peat”from A.M.A. PlasticsA.M.A. Plastics, in partnership with BVBSubstrates of The Netherlands, has a newproduct for North American growers.Called BVB Impress, it’s described as a newversion of “sticky peat” that’s suitable forpress block production and as a germina-tion mix in plug trays.

“BVB Impress uses white peat with amixture of other 100% organic materials

with no chemical additives, making it airier and more water absorbing for better roots; more dimension-ally stable so it holds its shape; and importantly, much lighter for lower handling and transport cost,” ex-plains the company in a press release for the new product.

They say that BVB Impress is suitable for propagation of many crops in both greenhouse and fieldproduction. Crops include, but aren’t limited to: lettuces, cabbage and other cole crops, cut flowers andherbs.

A.M.A. supplies propagation substrates, trays and equipment to a diversity of growers. They also offerwholesale distribution across the U.S. and Canada of hydroponic growing supplies for professional veg-etable growers, including BVB Sublime Substrate, Stonewool, Coir, Tomato Clips and Truss Supports,Twines, CO2 Tubing, poly ground cover, picking shears, and turnkey Dry Hydroponics lettuce/leafy veg-etable systems.

You can learn more about BVB Impress on A.M.A’s YouTube Channel.

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Insider

Philips Opens New High-TechFarming Research FacilityPhilips has opened a new state-of-the-art farming research facility at theHigh Tech Campus in Eindhoven, the Netherlands. At the GrowWise

Center, Philips will research customized LEDlight growth recipes to help indoor growersmaximize their yields year-round.

The new facility, said to be one of thelargest indoor farming research facilities inthe world, aims to optimize growth recipes forleafy vegetables, strawberries and herbs.Philips says they’re also interested in research-ing ways to grow more carbohydrate-richcrops indoors, such as wheat and potatoes.

The research center features four-layered mechanized planting racksin each of its eight climate-controlled rooms resulting in a total growingsurface of about 2,500 sq. ft. Each growing layer at the facility isequipped with Philips GreenPower LED lighting, which can be cus-tomized for various lighting treatments. Philips says that LEDs are highlyenergy efficient and produce less heat, meaning they can be placedcloser to plants for more uniform illumination.

Learn more about Philips’ LEDs on their YouTube channel.

Growtainer 2.0 More Productive,Efficient and AffordableThe new and improved Growtainer 2.0 will launch soon, according to

Glenn Behrman, presi-dent of GreenTechAgro. The Growtainer isa patent-pending grow-ing system containedwithin a specially de-signed and modifiedinsulated shipping

container. Developed for food production, horticulture or floriculture,the Growtainers offer efficient, climate-controlled environments forgrowing.

Growtainer 2.0 has been completely re-designed to be more afford-able, more efficient and more productive, ultimately offering a faster return on investment. It comes with a moveable and adjustable propri-etary Growrack system designed by GreenTech Agro and manufacturedin Holland.

Glenn says that Growtainer 2.0 can produce two to three times asmuch produce compared to other container-based products in the mar-ket today. They’re available in lengths of 40 ft. or 45 ft. and can be customdesigned for any climate.

“GreenTech Agro is finally ready to talk to investors and choose twoor three distributors,” says Glenn. “I said at Indoor Ag [Conference inMarch 2015] that I wouldn’t sell a Growtainer unless it was perfect. Andversion 2.0 is perfect.”

For more information, visit www.growtainers.com or email

The U.S. is slated to see an impressive array of new or expanding greenhouse vegetable operations in thenear future, according to Greenhouse Vegetable Consultant Gary Hickman. Gary says that over 670 acres ofgreenhouse vegetable production is in the planning stage or already under construction. This represents a30% increase in total greenhouse vegetable production in the U.S.

Also according to Gary’s data, Canada could see 98 new acres spread among three proposed projectsand Mexico could see 111 new acres spread among four projects.

Details on all of these proposed projects, including the name of the company and Internet contact/infor-mation link, are available in Gary’s June 2015 North American Greenhouse Vegetable Producing Companiespublication. Also listed in the publication are over 730 current North American growers, with information

and contact links. The website, with ordering information for this publication, is available at www.cuestaroble.com.

Organic Agriculture MoreProfitable to FarmersA new comprehensive study recently publishedin the Proceedings of the National Academy ofSciences, finds organic agriculture is more prof-itable for farmers than conventional agriculture.

In spite of lower yields, the global studyshows that the profit margins for organic agricul-ture were significantly greater than conventionalagriculture.

Researchers from Washington State University conducted a review of44 studies, spanning over 40 years, 55 crops and 14 countries on five con-tinents. The authors say this is the first large-scale synthesis of the eco-nomic sustainability of organic farming compared to conventionalfarming.

The study found that the premiums paid to organic farmers rangedfrom 29% to 32% above conventional prices. Even with organic cropyields as much as 18% lower than conventional, the breakeven point fororganic agriculture was a 5% to 7% premium.

Organic agriculture currently accounts for only 1% of cropland glob-ally, but the study says that there’s room for organic agriculture to expandand, with its environmental benefits, to contribute a larger share in feed-ing the world sustainably.

Read the full study at www.pnas.org/content/112/24/7611.abstract.

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Projects Plannedin 18 U.S. States

Six Fish Species for Commercial AquaponicsIt seems like Tilapia is the typical fish of choice to grow alongside plantsin an aquaponic system, but are there other options? Indoor Ag, in con-junction with Aquaponics Consultant Sarah Taber, recently created aninfographic comparing six fish species for commercial aquaponics.

Aquaponics is a food production system that combines growing veg-gies hydroponically with aquaculture (raising fish in tanks). Aquaponicsuses a symbiotic environment to grow veggies and fish together. By-prod-ucts of the fish serve as nutrients for the plants.

Traditionally a backyard or hobby pursuit, the commercial aquapon-ics industry is growing rapidly thanks to technology advances and de-mand for local sustainable food.

The six fish species reviewed in the infographic include tilapia, barra-mundi, sturgeon, hybrid striped bass, trout and Pacific salmon. The bene-fits, disadvantages and growth rates of each fish are discussed.

Sturgeon is one of the species that could be a strong contender for acommercial aquaponic system. Considered a sustainable alternative forswordfish, sturgeon grows quickly, has little competition in the marketand it’s optimum temperature is also optimum for plants. Its biggest dis-advantage is it’s not well recognized in the marketplace yet.

Cover Story

It’s one of the fastest-growingindustries in the United States.Some people call the phenom-ena “the green rush” and thoselooking to cash in “ganjapre-neurs.” TIMEmagazine calls it“the highly divisive, curiouslyunderfunded and strangelypromising world of pot science.”Here, we’ll simply call it

cannabis cultivation. No puns.No ganja jargon. This is just anopen-minded and objectivelook inside the industry ofgrowing a unique plant—cannabis. Whether you’re morally for

or against its widespreadusage, from a strictly businessstandpoint, the cannabis grow-ing market deserves some at-tention. ArcView, a cannabisindustry research firm, predictssales of legal marijuana willreach $3.5 billion this year, upfrom $2.7 billion in 2014 and$1.55 billion in 2013. Another report by a pro-

marijuana research and advi-sory firm, GreenWave Advisors,says that if all 50 states and thefederal government legalizecannabis, the annual sales forboth medical and recreationalmarijuana could reach $35 bil-lion by the year 2020. To putthat in perspective, the esti-mated annual sales of green-house tomatoes are $400million in the U.S. As more states legalize its

cultivation for medicinal use(or even recreational use) anddecriminalize its possession,the once-taboo cannabis leafisn’t raising as many eyebrows,even in our traditionally moreconservative horticulture industry.

The great legalconundrumEven though cannabis wascultivated and used through-out the majority of U.S. history,the plant was designated as aSchedule I drug in 1970, mean-ing that it has high potentialfor abuse and addiction, hasno medicinal value and pos-sessing it could land you inprison. Other Schedule I drugsinclude heroin and LSD.(Schedule II drugs, which aredescribed as having less abusepotential, include cocaine andmethamphetamine.) Nearly half of all states have

re-evaluated marijuana’s statusas a dangerous substance. Asof press time, 11 states haveboth a medical marijuana lawand have decriminalized pos-session of small quantities.Eight additional states havemedical marijuana laws andfive additional states haveeliminated jail time for pos-sessing small amounts of mari-juana. Four states (Colorado,Washington, Oregon andAlaska) have legalized mari-juana use for adults—bothrecreational and medicinal.Recreational marijuana istaxed and regulated similar toalcohol in these states. The problem is state laws

don’t trump federal law. It’s stillentirely within the scope ofthe federal Drug EnforcementAgency (DEA) to raid andprosecute marijuana growers,even if the growers are abidingby the laws of the state inwhich they operate. The unlaw-ful distribution or possessionwith the intent to distributemarijuana is a federal felony.The possession of 1,000 plants

could theoretically put agrower behind bars for 10years to life. “We get up and go to work

each day and sometimes it’seasy to forget that what we’redoing is still federally illegal,”explained Shayne Lynn, execu-tive director of a Vermont med-ical marijuana dispensary. (Seecase study on page 14.)The DEA continues to con-

duct raids, even in states withlegal medical and recreationalmarijuana programs, but inthis legal tug-of-war overcannabis, it’s believed theagency is yielding someground. Growers who workclosely with their state regula-tory agencies to ensure com-pliance have less concernabout a DEA raid than some-one not in good standing withthe state. The raids that makeheadlines typically stem fromsome kind of non-compliance(i.e., growing too many plantsor illegally diverting irrigationwater).Of course, this legal conun-

drum creates an unusual land-scape for running a business.Finding a bank willing to loanyou money or an insuranceagency willing to insure yourcrop and property is nearly im-possible. Many businesses areforced to operate in cash only.According to a fact sheet fromMarijuana Business Daily, lessthan 1% of financial institu-tions are willing to do businesswith the cannabis industry.

Cannabis scienceTo better understand cannabiscultivation, we turned to Ph.D.Plant Biologist and cannabisexpert Monique McHenry.

Considering Cannabis

by ANNIE WHITE, photos by Michael Tallman

The science andpracticality ofgrowing CEA’strendiest crop.

Cultivation Manager Josh Drew tends tocannabis plants at Champlain ValleyDispensary’s grow facility in SouthBurlington, Vermont. He wears Method 7grow glasses, specially designed forworking with a crop under HPS lighting.

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Monique is also the execu-tive director of one of the fourlicensed medical cannabis dis-pensaries in the state of Ver-mont. However, the operationmaintains a strict “no talking tothe press” policy, so when I satdown with Monique we strictlytalked science—no business.Originating in a small region

in central Asia, cannabis is oneof the oldest known cultivars. Itsuse is documented across10,000 years of human civiliza-tion. Ironically, today, it’s one ofthe least understood agricul-tural crops. Trialing and re-searching a Schedule I drug iscomplicated at the least, and atmost, impossible. Much of what we know

today is thanks to a team of Is-raeli scientists, led by a youngorganic chemist namedRaphael Mechoulam, whoteased out the unidentifiedcompounds in cannabis for thefirst time in the 1960s. Theywere the first to isolate tetrahy-drocannabinol (THC), the psy-choactive part of cannabis,which provides a “high” to usersor a sense of mild euphoria andrelaxation. It’s just one of about100 other cannabinoids—chemical compounds that alsoprovide relief to an array ofsymptoms including pain, anxi-ety, nausea and inflammation.Different cannabis strains havedifferent levels of cannabinoids,and frequently, medical mari-juana patients prefer strainswith less THC. Monique explains that differ-

ent cultivation factors also af-fect cannabinoid production,including sex and maturity ofthe plant, length of daylight, am-bient temperature, availability ofnutrients and UV intensity. Ascultivators strive to grow consis-tent medical-grade marijuana,it’s important to understandhow cultivation methods affectcannabinoid levels. Learning and improving cul-

tivation methods is uniquely

challenging for cannabis grow-ers. They can’t turn to thewealth of peer-reviewed journalarticles or university extensionproduction guides the way atomato grower can. Frequently,they conduct their own re-search trials to evaluate differ-ent production methods.Monique says the industry

needs more research. Breedingprograms are needed to de-velop strains that are mold re-sistant and pesticide research isalso greatly needed. Severalstates require pesticide safetytesting, but little is known aboutsafe use of pesticides incannabis.

Horticultural supply industryembraces cannabisFive or 10 years ago, it may havebeen challenging to find trustedand experienced companies tohelp design, build, outfit andsupply a cannabis-growing ven-ture. But today, much of the tra-ditional horticulture industry isinvolved, sometimes quietly, inthe cannabis market. Bernie Mantay, general man-

ager of Biobest Canada andBiobest USA, says that workingwith cannabis growers isquickly becoming an importantobjective for the company.While they don’t mentioncannabis on their website,Bernie says they’ll be promotingBiobest within the cannabis industry through alternatechannels. “I think, working together,

there are excellent opportuni-ties for both the cannabis indus-try and our industry,” addsBernie.Chris Lundgren, national

sales manager for Dosatron,says he’s been regularly workingwith the cannabis industry forabout two years. Chris notes thatwhile cannabis growers areoften behind the times on grow-ing technologies, they arethirsty for knowledge.

Some companies work withcannabis growers, but prefer tokeep it on the down low. “We donot broadcast to the traditionalindustry that we are solicitingbusiness from medical mari-juana growers, but we do nothide it either,” explains one U.S.-based greenhouse manufac-turer. “Most of our clients haveasked and we tell them we havesold projects.” Other companies, such as

greenhouse manufacturersRough Brothers and GGS Struc-tures, and environmental con-trols company Conviron,advertise openly to thecannabis industry through theirwebsites. GGS says their company has

been helping cannabis growersfor many years and has estab-lished an internal team ofknowledgeable growers andmanagers for this purpose.They only supply projects to

states in the U.S. that havepassed legislation allowingmedical and/or recreationalmarijuana cultivation. (Theyalso have projects in Canada, Jamaica, Israel and Uruguay.) “Due to the amount of re-

quests we receive from cultiva-tors, we have to be vigilant thatsupply enquiries are compliantto state laws and regulations,”explains Leigh Coulter, presi-dent of GGS.

SHS Griffin Greenhouse Sup-plies says they’ve launched anew marketing campaign toconnect with the expandingcannabis market. They advertisein key cannabis industry publi-cations, as well as attend indus-try trade shows. They say they’recurrently developing a websitespecific to the cannabis andCEA markets.

From traditionalhorticulture tocannabis cultureAs more states are legalizingmedical marijuana and licens-ing growing operations, somegrowers of ornamental and/oredible crops are wondering ifthey could be successful grow-ing cannabis. Leigh Coulter says that it’s

absolutely feasible to transitionfrom ornamental/edible green-house crops to cannabis, butcautions that it’s a significantchange in business and shouldnot be approached lightly. “Cannabis is a very different

business model from ornamen-tals and traditional greenhouseedibles,” said Leigh. “Distribu-tion, marketing, financing andregulatory issues are all differ-ent, so smart growers start withbuilding a business plan for thenew cannabis reality, then find apartner like GGS who can helpput the whole package to- >>>

The cannabis crop is monitored at Champlain Valley Dispensary’s grow facilityin South Burlington, Vermont.

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Cover Story

gether: structure, mechanical,electrical, irrigation, computercontrol designed to optimizethe cannabis crop environment.”Shane Hutto, owner of Hor-

ticultural Solutions—a Denver,Colorado-based cannabis con-sulting company—helpsclients design, plan and imple-ment growing operations. Be-fore becoming a cannabisconsultant, Shane served as aNorth American technical ad-visor for Grodan, a Nether-lands-based manufacturer ofhydroponic substrates.

Shane has helped growersof edible greenhouse cropsretrofit their facilities (or ex-pand them) to grow cannabis.“It’s much easier for me to turna hydroponic tomato growerinto a cannabis grower than toturn an experienced cannabisgrower into a tomato grower,”explains Shane. “The principlesare very similar, but mostcannabis growers have neverused the level of technologyutilized in a modern tomatohouse.” Cannabis cultivation is

unique, explains Shane, in thatit involves facets of multiplecrops. Some aspects of theflowering plant require cul-tural practices similar tochrysanthemums. Other as-pects, such as pruning and nu-trition, are more similar totomato growing.Another consideration in

entering the cannabis marketis the crop’s long-term prof-itability. “I think the next fiveyears will show astronomicalgrowth, and a decade fromnow, I would expect a market

decrease and eventual level-ing off,” hypothesizes Shane.“In 10 years, I expect it will bea similar market to tomatoes—there will be slim margins andonly the biggest and best willmake worthwhile money.”If Shane’s predictions are

true, the next five years couldbe a unique time in controlledenvironment agriculture. Theindustry may see a surge ofnew growers, new-to-cannabisgrowers and a rush forcannabis information andtechnology.

From Tomatoes to CannabisChris Williams doesn’t fit the physical stereotype of a marijuanagrower. He isn’t tattooed, pierced or even a little rough around theedges. He’s friendly, professional and brings an impressive résuméof growing hydroponic greenhouse tomatoes to his job as cultiva-tion manager at Champlain Valley Dispensary in Burlington, Ver-mont.Chris, a Vermont native, became smitten with controlled envi-

ronment agriculture when he was just 19 years old. He travelednorth to Charleviox, Quebec, mentoring with the head grower atSerres LaCoste, a two-hectare greenhouse specializing in beefsteaktomatoes. After learning the ropes, Chris returned to Central Ver-mont to be the head grower at Vermont Hydroponic Produce.After growing beefsteak and cluster tomatoes hydroponically in

Vermont for six years, Chris wanted a new challenge. He went onto spend time as the head grower at BrightFarms’ one-acre green-house in Yardley, Pennsylvania, and as an assistant grower withD’Vine Ripe in Australia, managing 66 acres of glasshouse tomatoes. With his wife expecting their first child, Chris decided to return

to the U.S. in early 2015. He considered returning to Vermont Hy-droponic Produce, but was told, amiably, that he was too expensivefor the small company. Despite having never grown cannabis andknowing very little about the plant itself, he reached out to theChamplain Valley Dispensary and soon he re-launched his careeras a cannabis cultivator. “As a grower, I’ve always looked for the next best thing.

Cannabis is that thing now. It’s the cutting edge,” explained Chris,who is unabashed to talk about his leap from growing tomatoes togrowing cannabis. Chris says that while tomatoes and cannabis have different cul-

tural needs, managing the growing environment is very similar. “I’msomeone who thrives on data. I grow by numbers,” he explains.“Consistency and uniformity are important in a tomato operationand are even more important growing medical cannabis.” As medi-cine, each batch needs to be grown the same to achieve the con-sistent cannabinoid levels patients expect.As for pay, Chris says that just like any other crop, wages reflect

the scale of the operation. Right now, he’s the cultivation manager

for a small cannabis growing operation, but he’s hopeful that asthe company expands, so will his responsibilities, and so will hisearning potential. Now with a young family, safety is a consideration for Chris. As

an employee, he does not own the cannabis crop, so in the un-likely event of a legal intervention, he would not be personally li-able. Chris says he feels completely safe going to work each dayand would even feel comfortable tending to a middle-of-the-nightalarm, if need be. Multiple measures are in place to ensure the fa-cility’s security. When asked what some of those security measures are, Chris

quipped, “Well, we’re here aren’t we?” referring to the fact I was in-terviewing him in a public café and not at their growing facility.The facility is in an undisclosed location, somewhere in SouthBurlington, Vermont, intentionally in close proximity to the policedepartment. Only people with official business (press do not qual-ify) are permitted to visit the facility and all visits must obtainprior approval from Vermont’s Department of Safety, the agencyoverseeing medical marijuana operations in the state. Chris said that his family, friends and former colleagues are sup-

portive of his latest growing venture. He hasn’t faced any criticismand he jokes that probably the most common response from peo-ple who know him is “we figured it was just a matter of time.”

Cultivation Manager Chris Williams checks cannabis plants at ChamplainValley Dispensary’s grow facility in South Burlington, Vermont.

GROWER PROFILE

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14

Cover Story

Most universities are reluctant to affiliatethemselves with the federally illegal plant,so research proposals remain shelved. How-ever, the lab of Evolutionary Biologist Dr.Nolan Kane at the University of Colorado atBoulder is working on creating an ultra-highdensity genetic map of cannabis.

“This will revolutionize cannabis breed-ing, bringing the genetic tools and resourcesup to the level of all but a handful of crops,”says Nolan. The project will sequence two di-vergent lines, Cannabis sativa and Cannabis

indica, as well as 96 to 142 hybrids of thoselines, to make a very high-quality geneticmap.

Funding the research has proven trickierthan studying, say, a tomato. Presumably forlegal reasons, the University of Coloradodoes not accept money from the cannabisindustry or people/companies explicitly rep-resenting the cannabis industry. So Nolan setup a nonprofit foundation and a bank ac-count through a separate credit union, whichcan accept donations from all people andcompanies to help fund the research.

Champlain Valley DispensaryVermont has a small, but tightly regulated medical cannabis pro-gram, and it’s possible the state legislature will legalize the recre-ational use of marijuana in 2016. The industry in Vermont is, ofcourse, just a sliver of the cannabis boom that’s happening instates like Colorado and California, but Vermont does offer aunique look at what operating a fully transparent growing opera-tion in a tightly regulated state looks like. Chris Williams and Josh Drew manage Champlain Valley Dis-

pensary’s 5,000 sq. ft. indoor grow facility—a small operation bymost standards—but are currently expanding five-fold to a new lo-cation with 25,000 sq. ft. of indoor grow space, a laboratory, pro-cessing facility and outdoor space to add greenhouse productionin the future. Unlike Chris, cultivating cannabis has been 25-year-old Josh

Drew’s career goal since starting college as an environmental hor-ticulture major at the University of Maine—Orono. Although theuniversity didn’t offer any training in cannabis cultivation, Joshtook what he learned in his horticulture, sustainable agricultureand business classes and figured out how to apply it to the plantthat fascinates him the most—cannabis. Josh has been managingand training the cultivation team at Champlain Valley Dispensarysince 2013 and has developed many of the cultivation proceduresand protocols.To keep their two dispensaries in supply, they grow 52 weeks a

year, on what they call a “perpetual grow” rotation. They grow be-tween 30 and 40 cannabis strains, with an emphasis on 10 to 15 oftheir best sellers. All are grown hydroponically in coco mediaunder 1,000-watt high-pressure sodium lighting. They’re also trial-ing plasma lighting and LEDs.As part of their integrated pest management program, they fight

pests proactively with a well-rounded palette of beneficial insects.With good IPM and strict sanitary protocols, so far, they’ve neverneeded to use a pesticide. Personal hygiene is important in the facility. The cultivation

team wears facility-specific clothing, gloves and hairnets, and rou-tinely wash their hands and step through disinfectant footbaths.Chris says the sanitary protocols are on par with what he’s seen atother large-scale greenhouse vegetable growers, but he believesthey keep their facilities cleaner than most cannabis growers.Currently, they use a commercial water-soluble fertilizer, not

specifically formulated for cannabis. Albeit expensive, they say itworks great. As they expand, they plan to start mixing their ownnutrients, allowing for more customization, and ultimately, savingmoney.Every cannabis plant in their facility has a unique code and is

tracked with the help of a computer program from cutting throughharvest—a process that takes about two and a half to four monthsdepending on the strain. This kind of tracking system is mandatedby the state. It helps monitor the crop’s consistency, which is impor-tant to patients, but it also makes it very difficult, if not impossible,for a plant or a portion of the harvest to go missing. To work in the industry in Vermont, individuals must pass a

state-mandated FBI background check. Folks with blemishedrecords won’t be hired. Josh says that members of their cultivationteam don’t necessarily need a college degree or even experiencegrowing cannabis. Most importantly, they need to be attentive to

details, patient and willing to meticulously follow the company’ssanitation and cultivation protocols. “The biggest challenge with new employees is just getting rid of

their bad habits,” says Josh. “It can be hard for some people to un-derstand that we don’t always do things the way they’re used to.We’re growing medicine and our protocols are strict.”All “mother” plants (the source of cuttings) have to be donated

to the facility by patients. Legally, that’s the only option. Cannabisplants cannot cross state lines, and currently, there is no source ofcannabis genetics in Vermont.

The business side of growing cannabisChamplain Valley Dispensary’s Executive Director Shayne Lynnlooks like any other businessman you’d find walking down ChurchStreet in Burlington. About seven years ago, Shayne started following the medical

marijuana movement in Vermont, attending meetings at the statehouse and advocating for its legalization. In short, his interest inthe industry grew, eventually leading him to apply for (and re-ceive) a license to grow and sell medical marijuana in 2012. Banks loaning money to cannabis businesses are nearly un-

heard of, so Shayne secured “contributors,” as he calls them, to in-vest in the nonprofit business he established. Two years afteropening his dispensary door for the first time, he’s grown from 80to 800 patients and has so many people interested in investing, hecan handpick the contributors he wants to work with. Shayne feels fortunate to have found a couple of credit unions

that were willing to work with his business. (In other states, manycannabis growers are cash-only businesses.) This was an impor-tant step in trying to be as transparent as possible. The bank tracksall of the money in and out of the business. There’s nothing tohide.Protecting the company’s physical assets has proven to be

uniquely challenging. He’s found that insurance companies arehesitant to work with cannabis businesses because it’s a relativelynew industry, there are still some uncertainties, and there just isn’tenough data for insurance companies to feel safe hedging theirbets. Shayne says he does have crop insurance, but he pays a lotfor a very minimal policy. Looking forward, Shayne plans to grow the business to provide

more products to more patients. If the recreational use of mari-juana is legalized in Vermont next year, a whole new market willopen up, but so will the potential for new competition.

CASE STUDY

CANNABIS RESEARCH

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An increasing number of greenhouse ornamental plant growers arelooking to expand into edible crops. There are also field vegetablegrowers who would like to expand their production to include cropsin a protected or controlled environment. Some of the easier andfaster crops for growers to try to produce in structures are lettuceand other leafy greens.

One of the issues these growers are facing is what varieties of let-tuce can be grown in a greenhouse environment. Much of the com-mercial lettuce breeding is focused on outdoor field production.Growers looking to expand their lettuce offerings beyond com-monly produced greenhouse varieties usually have to do their owntrials, looking for field-bred and greenhouse-type varieties that canbe adapted to a greenhouse environment.

EXPANDING GREENHOUSE VARIETIESUniversity of Arkansas horticulture professor Mike Evans said he’sconstantly receiving inquiries from growers about what lettuce vari-eties can be grown in greenhouses.

“At Cultivate’14, we surveyed growers who participated in one ofthe greenhouse vegetable seminars about their educational and re-search needs,” Mike said. “One of the growers’ responses was theneed for variety information.

“If you look at seed catalogs, most of the information describinglettuce varieties is based on field production, not greenhouse. So if agrower wanted to grow lettuce hydroponically in a greenhouse dur-ing the winter, there’s little information available. If a grower wantedto use nutrient film technique or deep flow floating systems in agreenhouse, there’s basically little information on how lettuce vari-eties would do in these specific production systems. Most of the pro-duction information is field-based.”

Mike said there’s also a need for evaluating lettuce varieties forfall, winter and spring greenhouse production. He said these varietyevaluations need to be done in different regions of the country tosee how they perform under different climates.

LETTUCE VARIETY EVALUATIONSUniversity of Arkansas researchers selected 65 lettuce varieties forevaluation in greenhouse production systems. A nutrient film tech-nique and deep flow floating system were used for the trials.

“Our goal with the variety trials was to generate better and morevariety information, and to determine which varieties would workbest in climates similar to ours,” Mike said. “We especially wanted tobe able to make variety recommendations across a production year.That is, varieties which work well in the fall, winter and spring.

“There are certain varieties that do well during winter, but assoon as the days start getting longer, the variety begins to bolt. Or a

variety may do well in the fall and spring, but during the lowest lightlevels of winter, it has some type of production issue.”

Mike said the information that’s been collected is for lettuce vari-eties that perform well in a glass greenhouse in Arkansas.

“These varieties may not respond the same way in Michigan, Ari-zona, Florida and Texas,” he said. “They also won’t respond the sameway in locations where the light and humidity levels are different.These trials are probably good recommendations for growers in cli-mates similar to ours.”

Lettuce varieties were grown from September through May. No

Lettuce Tell You What to Grow

University of Arkansas researchers trialed 65 lettuce varieties to determine their potential forproduction in greenhouse hydroponic systems.

by DAVID KUACK

Research

University of Arkansas researchers selected 65 lettuce varieties for evaluation in greenhouse production systems.

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crops were grown in June, July and August. Four crops were pro-duced during the fall to spring cycle.

“Some growers try to grow during the summer months by chill-ing the nutrient solution,” Mike said. “We weren’t set up for summerproduction. Having trialed 65 varieties, we will probably select 15 ofthe best-performing varieties to evaluate for summer performance.For the summer evaluations, we will have to use a different green-house set-up in order to chill the nutrient solution.”

MEASURING GROWTH RATEMike said one of major growth parameters measured was biomassproduction or growth rate.

“The quicker the plants grow, the shorter the production cycle,” hesaid. “Every day on the bench is cost to the grower. We looked atfresh weight and dry weight—two measures of growth. Some grow-ers let lettuce grow for a specific amount of time. Other growers tryto achieve a specific weight.”

Mike said the lettuce crops were grown on a 42-day productioncycle in both the NFT and deep-flow systems. At the end of the 42-day cycle, the lettuce was harvested and measurements were taken.

“Sometimes if a variety is a fast grower, the lettuce might exceedthe weight that a grower would want,” Mike said. “That tells us this va-riety could have been grown in a much shorter period of time. Or a

variety that didn’t reach a minimum weight at the end of the 42-daycycle was considered a slow grower. Fresh and dry weights wereused as a measure of how fast a variety can grow. How fast can a va-riety put on biomass? That is what growers are selling—biomass.”

Mike said there were similarities in how varieties performed inthe two production systems.

“If the varieties did poorly in NFT, they tended to perform simi-larly in deep flow, too,” he said. “If a variety did well in NFT, odds werehigh that it did really well in deep flow.”

IDENTIFYING DISORDERSMike said the two most common problems he hears about lettucefrom growers are powdery mildew and tipburn.

“Ninety percent of the calls I receive are about these two prob-lems,” he said. “We rated the lettuce varieties we trialed for tipburnand powdery mildew. Powdery mildew in our region of the countryis the disease that can often give growers fits. It can really wallop alettuce crop. We also measured the incidence of tipburn, which canbe a problem on a number of greens.”

Mike said semi-heading and heading (butterhead) types seem tobe more prone to tipburn.

“What happens is that, as these varieties start to form heads, thereis an area of high humidity,” he said. “There is this little microcli-

A nutrient film technique (foreground) and deep flow floatingsystem were used for the lettuce trials.

Lettuce varieties performed similarly in the two greenhouseproduction systems. If a variety did well in nutrient film tech-nique, it performed similarly in the deep flow system.

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mate of high humidity. If a grower is growing under real high humidity, hasstructures with poor air circulation or the nutrition levels aren’t right, a calciumdeficiency can occur. These can create a tipburn problem. We saw much lesstipburn on varieties that tend to be loose-leaf types.”

EVALUATING YEAR-ROUND PERFORMANCEHaving identified lettuce varieties that did well for fall through spring produc-tion, Mike is planning to select 15 to 20 of these varieties for a summer evalua-tion trial.

“We want to take the best varieties from our trials and evaluate them duringa summer production run,” he said. “We will chill the nutrient solution to below70F.We would also like to look at how these varieties perform without any chilling.”

Mike wants to determine if marketable-size plants can be produced beforebolting occurs.

“We are particularly interested in finding varieties that are highly resistant tobolting,” he said. “We would like to identify lettuce varieties or other greens thatwould offer growers options for summer production. The ideal situation wouldbe for growers to be able to grow these crops without having to make an invest-ment in a chilling system. The ideal for a grower would be able to produce andmarket a crop that had enough size and weight before it bolts.”

For more, contact Mike Evans, University of Arkansas, Department of Horticulture at(479) 575-3179 or [email protected], http://hort.uark.edu/5459.php.

Some of the information presented in this article first appeared in the Hort AmericasJune 2015 Newsletter, http://www.hortamericas.com. The original article is available onthe Hort Americas Blog, http://www.hortamericas.com/hort-americas-blog.html.

Top-Performing Lettuce VarietiesThe following lettuce varieties did well in the fourgreenhouse production trials conducted at the University of Arkansas.

BUTTERHEAD TYPESAdrianaDeer TongueNancyRexSkyphos (pictured)

FANCY LEAF TYPESBlackhawkCavernetDark Red Lollo RossaNew Red FireOutredgeousRed SailsRuby Sky

OAK LEAF TYPESOscardePanisseeRouxai

ROMAINE TYPESGreen Forest

Red RosieRidgelineSalviusTruchas

DAVID KUACK is a freelance technical writer in FortWorth, Texas. He can be contacted at [email protected].

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Increased consumer demand forfresh, high-quality produce has ledsome bedding and potted plantgreenhouses to consider vegetablesfor produce sales. Greenhouse opera-tions are keen to put their facilities touse during their offseason. Doing sohas the potential to increase their an-nual net revenue by growing anothercrop to help pay for fixed expenses(such as depreciation, property taxes,insurance, management salaries).Adding in vegetable crops during theoff-season can also allow operationsto keep labor employed year-round.

The first thing to consider withany new crop is the market channelthat will be used to sell it. Some mar-ket channels include a retail store,farmer’s markets, restaurants andlocal supermarket chains. Eachgrower must carefully scrutinize thecosts of growing vegetables againsttheir potential returns. Because thisrequires a lot of data on crop laborand input needs, as well as time todevelop new markets, I’ve observedmany bedding plant growers startingwith veggies at a small-scale, ex-ploratory basis.

SUMMER TOMATOES INCONTAINERSFresh, vine-ripened tomatoes are aconsumer favorite. Tomato plantshave high light demand for decentyields, a minimum daily light integral(DLI) of 20 moles of photosyntheti-cally active radiation per square meter per day (i.e., 20 mol/m2/day).To put this into perspective, suggested DLI requirements for high-quality bedding plants are on the order of 10 to 12 mol/m2/day. Fortomatoes, yield goes down by 1% for every 1% decrease in light.Therefore, year-round production requires supplemental light inmuch of the U.S. Because greenhouses are often idle from summerthrough early fall and have high natural light during this period, it’san ideal time to grow greenhouse tomatoes. Tomato plants are typi-cally grown in rock wool slabs or containers, such as 3-gal. Dutch

buckets (Figure 1) or 5- to 10-gal.round containers.

CORNELL TRIALWe conducted a trial at Cornell Uni-versity growing greenhouse tomatoesin a production system that could beadapted readily by bedding plantgrowers, using 5- to 10-gal. containerswith potting mix and drip irrigation.We wished to determine the influ-ence of container size on the fruityield of greenhouse tomatoes grow-ing in containers. The containersused in this study were Smart Pots,durable, soft-sided fabric containersoften used in the nursery industry forroot-pruning and aeration (Figure 2).

Seeds of Primo Red, a determi-nate large beef-steak tomato, werestarted by a commercial propagatoron March 1. Seedlings were trans-planted into square 3-in. pots. OnApril 15, we established our green-house trial—too early for a beddingplant grower—but we believe theycould have transplanted and held ata higher density for some weeks untilmore greenhouse space was avail-able. Seedlings were transplantedinto Smart Pots with either a 5-, 7- or10-gal. volume. The containers werefilled with a peat/perlite-based sub-strate (Lambert LM-111). At this time,plants were placed in the green-house at a final spacing. Recom-mended plant spacing is 1 plant per4 to 6 sq. ft. (Under low light, the

wider spacing is suggested.) We chose a spacing of 1 plant per 5½ sq. ft. to give us ample

space to get to each plant. From the center of each plant, they werespaced 20 in. apart between the plants within a row and 40 in. apartbetween rows. Plants were on a drip irrigation with two emitters perplant. Plants were placed in an older glass greenhouse with fan andpad cooling. No supplemental light was used. In late May, a light ap-plication of shading compound (about 30% shading) was applied tothe exterior of the glass to help with temperature control. Our green-

Growing Greenhouse Tomatoes in Containers

A good way to jump into producing finished greenhouse vegetables from bedding plants is to grow tomatoes.

by NEIL MATTSON

Research

Figure 1. Commercial greenhouse tomatoes growingin Dutch buckets (also known as “Bato” buckets).

Figure 2. The containers used in this study—SmartPots—are a durable fabric container.

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house temperature set points were 75/63F(23/17C) day/night temperature.

Tomato plants have higher demands for mag-nesium, potassium and calcium than traditionalbedding and potted plants. Therefore, 25-lb. bagsof “complete” water-soluble fertilizer used for pot-ted flowering crops cannot typically be used asthe sole fertilizer source. Besides our standardbedding plant fertilizer 21-5-20 (which containsmicronutrients, but no calcium or magnesium),we added calcium nitrate, potassium nitrate andmagnesium sulfate (Epsom salts). Calcium ni-trate isn’t compatible with 21-5-20 because a pre-cipitate forms. Therefore, we used two stock tanksto prepare our fertilizers.

Because we had only one fertilizer injector,we alternated between the two stock solutions.During weekdays we used 150 ppm N from 21-5-20 plus 50 ppm magnesium from magne-sium sulfate. During weekends, we switchedstock tanks to deliver 150 ppm nitrogen from cal-cium nitrate and 100 ppm N from potassium ni-trate. We monitored substrate electrical conduc-tivity and pH weekly. When substrate pH wasgreater than 6.8 (optimum pH is 5.5 to 6.0), weswitched to a more acidic fertilizer 21-7-7 inplace of the 21-5-20 for a few days to bring pHback down. For a more in-depth article on fertil-izer recipes for hydroponic fruiting crops andleafy greens, see “A Recipe for Hydroponic Suc-cess” in the January 2014 issue of Inside Grower.

Although the plants we used were determi-nate, they still grew several feet high, 6-ft. in ourcase, and needed to be trained to keep them up-right. We suspended 9-gauge wire 7 ft. above eachrow and hung a spool of string from the wire tothe base of each plant. Periodically, we used plas-tic clips to secure the stem below a strong leaf tothe string, using clips about every foot of stem.

Early in the growing season, we removed lat-eral stems, or suckers, when they were 1 in. long.This encourages development of fruit instead ofvegetative growth. About two months after trans-planting in mid-June we let a few lateral stemsgrow on each plant, these provided fruit later inthe season when the main stem had stoppedproducing. If an indeterminate variety of toma-toes is used, all suckers are typically removed. Inaddition, when indeterminate plants get taller,string is unwound from the spool and plants areleaned over and lowered so you can still reachthe upper part of the plant. We removed olderleaves up to the ripening fruit. This is importantto promote good airflow to reduce disease inci-dence and to reduce habitat for insect pests. Re-garding pollination, we didn’t use a handpollinator or bumblebees to aid in pollination of

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flowers; however, these methods are reported to improve fruit yields by about 20%.Fruits were harvested three times a week at the red stage (i.e., vine ripened).

Our first fruit were ready to harvest on June 4—about 7 weeks after transplanting(Tables 1 and 2). Plants yielded 1 to 2.5 lbs. of fruit in June. Peak harvest months wereJuly, August and September, when plants produced about 6, 5 and 4.5 lbs. per month, re-spectively (Table 1).

We concluded the trial at the end of October, as plants were yielding few marketablefruit by the end. Average fruit size was about 13 oz. for the first month and 9 oz. there-after. We believe the decrease in fruit size is because later on there were many morefruits per plant to which the plant’s energy had to be divided between. Interestingly wefound that container volume of the Smart Pots significantly impacted plant yield. Cumu-lative plant yield over the entire crop season was greatest with the 7-gal. Smart Pots withan average of 24.5 lbs. per plant (Table 2). Plants in the 5- and 10-gal. containers pro-duced about 20 lbs. of tomatoes per plant. We’re unsure of the reason behind this, butwe propose that the 5-gal. containers didn’t hold quite enough water/nutrients for

Table 1. Monthly fruit yield (pounds per plant)* in response to container size.

Table 2. Cumulative fruityield (pounds perplant)* during the entireproduction cycle.

>>>

*Data are averages +/- standarddeviation of 10 plants pertreatment combination.

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our fertilizer regime, while 10-gal.containers may have held too much,thereby keeping plants more vegeta-tive and less reproductive.

Overall, our study shows SmartPots could be successfully used toproduce container tomatoes in thegreenhouse. Our methods for con-tainer tomatoes can be readilyadapted by bedding plant growerswishing to use summer greenhousespace. As with any new crop, growersshould begin with small-scale trialsto learn about the specific produc-tion system and determine if a profitcan be made given their market andcrop expenses.

Disclaimer: Mention of trademarks or brandnames is for informational purposes only anddoes not imply its approval to the exclusion ofother products that may be suitable.

NEIL MATTSON, [email protected], isAssociate Professor and Greenhouse ExtensionSpecialist at Cornell University. We thank HighCaliper Growing, makers of Smart Pots, forfunding this study.

Tomato plants from the Cornell trial (supplemental lights weren’t used).

Research


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From Football

Grower Profile

Managing a greenhouse operation may seem like alofty feat for a 25-year-old, but that’s exactly the type ofchallenge that RJ Malseed, Farm Manager of VerticallyLocal Farm, thrives on.

Growing up in Delaware, 14-year-old RJ had hisfirst taste of horticulture at his local garden center, Always the Garden. It was here that RJ worked duringhis high school years, learning about gardening andgrowing in general. Inspired by the owner Tim Ross, RJabsorbed Tim’s knowledge about horticulture, frombackyard perennials to ornamentals.

“I took on an interest right away. Something aboutplants—specifically the veggies production andplants—caught my attention,” said RJ. “I was hooked.”

Recruited to Delaware Valley College on a footballscholarship, RJ briefly contemplated majoring insports management, but quickly returned to horticul-ture. Part of the learning criteria was an internship,which would offer the hands-on experience to supple-ment the in-class experience. RJ applied at Ford HookFarm, a field trial farm run by Burpee Seed Companyduring his junior year. Here, manager Sharon Kaszanmentored him, teaching RJ about field production—including the value of crop rotation, disease and in-sect maintenance, and the impact of Mother Nature.

“Simply being on the farm and getting your handsdirty taught me more knowledge than any classroom,”said RJ.

Jersey boyOne thing that RJ truly values is the knowledge thathe learns from others, recognizing that it’s these men-tors that have helped shape where he is today.

Upon graduation with a degree in horticulture andgreenhouse management, RJ had several job offers, in-cluding one from Burpee Seed. However, it was aphone call from Jerry Ambrogi, RJ’s high school foot-ball coach and owner of Ambrogi Foods in Paulsboro,New Jersey, that truly captured RJ’s attention. Jerrywanted to start a local farm that would sell directly tohis distribution company, and he was looking for anindividual to help start and run the farm. RJ jumpedon the opportunity.

It was 2012, but RJ’s new career didn’t begin on thefarm—he began working directly for the distributioncompany. Here, RJ learned the needs of the customer,both in the type and quality of product that theclients were looking for and then sell. Knowledge thatwould help RJ become aware of the quality and typeof produce that would be needed to appeal to theAmbrogi Foods distribution market. RJ was now readyto launch into developing the farm.

The farm project began in February 2013, whenJerry purchased a 7-acre old horse farm in Pilesgrove,New Jersey. “It didn’t have electric or running water;the farm still had horses on the property at the time,”RJ recalls. “Jerry said, ‘Here’s your farm. Make it

happen.’”Together with the help of Mike Saggiomo, general

manager of Ambrogi Foods, RJ began the transforma-tion from horse farm to a greenhouse operation. Thefirst few months were spent in full construction mode,from grading the land to running electricity and in-stalling a well. The end project needed to be able togrow the microgreens and hydroponic lettuce thatJerry wanted for his company, so RJ and Mike built thefacilities that would provide the optimal environmentto grow these products.

The initial build included three greenhouses—twothat were stand-alone hoophouses and one hydro-ponic greenhouse for the lettuce. The microgreens,which include arugula, cilantro, basil and a micromix,were grown in a four-level wood and chicken wiretable with 20-row seedling flats. In October 2014, man-ager Marc Sammacicci joined the team, bringing withhim his extensive greenhouse knowledge. Marchelped plan and complete the new expansion, whichincluding shifting the micro greenhouse to hydropon-ics, eliminating soil and peat moss.

“We started the houses in 2014 and ever since thenwe’ve been expanding,” said RJ. “I just finished an ex-pansion on my hydroponic greenhouse and I’m hop-ing to do my microgreens in hydroponic productionas well. “

Converting to a hydroponic system for the micro-greens would increase profitability, shared RJ, prima-rily because they no longer have to rely on using peatmoss, which had become a major expense. In addi-tion, it frees up space to experiment with other thingslike growing tomatoes inside the greenhouse year-round.

“I would love to make our whole farm hydroponic.That’s kind of the goal down the road,” said RJ.

Learning hydroponicsDespite not having a formal hydroponic education, RJbecame his own teacher, seeking out resources onlineand learning hands on.

“I didn’t think of doing hydroponics full scale untilI had the opportunity to work with Jerry and helpthem with it,” said RJ. “I did have a bit of trouble in thebeginning when we started the farm; it didn’t run assmoothly as it could. But after some hands-on trialsand tribulations, we learned what works. “

One of RJ’s first crops of hydroponic lettuce hadpythium. It was through this negative experience thatRJ not only learned how to treat the problem, butfound ways to prevent the issue from occurring in thefuture. They were able to save 60% of the crop.

“I learned from that day on to change the water inthe source tank every 10 to 14 days to keep properoxygen levels in the water for good root develop-ment,” said RJ.

A young go-getter

turned his love for

horticulture into a

career with a

strong future in

hydroponics.

by ANNE-MARIE HARDIE

25

RJ Malseed, Farm Manager of Vertically LocalFarm in Pilesgrove, New Jersey, took tohorticulture at an early age. He was recruitedto Delaware Valley College on a footballscholarship, and majored in horticulture.

Vertically Local Farm was originally a 7-acre horse farm thatdidn’t have electric or running water when RJ’s former highschool football coach Jerry Ambrogi, owner of Ambrogi Foods,bought it in 2013.

RJ sees hydroponics as the future for smallfarmers, allowing them to produce year-round with less expenditure.

26

Fertilizers

Thoughts on Using Organic Fertilizersfor Greenhouse Plants

Growing organic? Here are your best choices.

by DOUGLAS COX

For a number of years, I’ve stud-ied the use of organic fertilizersfor growing commercial green-house crops. To start, I chose toevaluate fertilizers that could bemixed and applied using meth-ods familiar to growers using tra-ditional water-soluble or granularslow-release chemical fertilizers.

Right now, I recommend Na-ture’s Source 3-1-1 liquid fertilizerand Sustane 8-4-4 granular slow-release fertilizer. Both of these arereadily available, cost effective,OMRI-certified and have goodlabel directions for greenhouses.I’ve also evaluated or am cur-rently trialing other organic fertil-izers and these are listed withcomments in the table accompa-nying this article.

Two liquid fertilizers that mayhave promise one day are Bom-bardier 8-0-0 and Espartan 2.0-3.03-2.6 manufactured by Kimitec

in Spain. At this time, these havelimited availability, are rather ex-pensive and the labels aren’t writ-ten for greenhouses. Nature’sSource, Bombardier and Espartanare plant extract fertilizers andSustane is made from poultrywastes.

My work has led me to recom-mend using different organic fer-tilizers in combination ratherthan relying on one fertilizer. Isuggest using Nature’s Sourceand Sustane together to take ad-vantages of each fertilizer’sstrengths. This would be done byincorporating Sustane in thegrowing medium at planting andthen fertilizing on a regular basiswith Nature’s Source, startingabout four weeks after planting.Combinations should be consid-ered regardless of what brands ortypes of organic fertilizer arebeing used.

Here are some more impor-tant specific recommendationson how to use organic fertilizersto grow greenhouse plants: 1. Mixing and application. Thefish fertilizers and plant extractfertilizers are sold as concen-trates and they must be diluted inwater to be safe for plants. Na-ture’s Source, Bombardier and Es-partan have a pleasant “beery”aroma as concentrates, butwithin seven days of being mixedwith water, they “spoil” and de-velop very unpleasant odors. Theodor, however, is not as bad asfish fertilizer. The nutrient value ofspoiled fertilizer is unknown andthe colonies of bacteria that de-velop may plug irrigation lines, sodiluted fertilizer solution shouldbe used as soon as possible aftermixing.

Fish fertilizer has the thickestand least consistent solution and

should be agitated before mixingwith water. Bombardier and Es-partan concentrates are “syrupy,”but mix well with water. Nature’sSource is the thinnest concen-trate, and it mixes well with waterand can pass fertilizer injectors.

Sustane is a granular fertilizerthat would be mixed with thegrowing medium before planting.It’s the easiest organic nutrientsource to use in combinationwith the liquid types. 2. Fertilizer analysis. Some or-ganic fertilizers supply only oneor two of the NPK elements. Anexample is Bombardier, which is8-0-0, so a grower using Bom-bardier would have to use otherfertilizer(s) to supply P and K. Irecommend Sustane, which hasan 8-4-4 analysis or some othercomplete NPK granular organicfertilizer.

Fertilizer Type Analysis Comments Neptune’s Harvest Organic Fish fertilizer

Liquidemulsion

3-1-5 Fish fertilizer has been widely used as organic fertilizer for many years. The emulsion needs to be mixed well to give a consistent materialfor dilution and application. Once mixed with water, it spoils and develops a bad odor. Mix fresh and use immediately. Leaf chlorosis,probably due to ammonium toxicity, is common. OMRI listed.

Plant Natural alfalfapellets

Pellet 5-1-2 Alfalfa is a legume and, therefore, is rich in nitrogen. The pellets are often used as animal feed and are similar in size and shape to woodpellets used in pellet stoves. Pellets supported the plants for about 40 days and then were exhausted of nutrients. Also, they swell whenwater is added, greatly increasing the volume of medium in a pot. Limited potential for this fertilizer.

Kimitec Bombardier Liquid 8-0-0 Bombardier is a plant extract fertilizer made from fermented sugar beet molasses. It works well with Sustane, which supplies the absentP and K. Some plants develop interveinal chlorosis due to ammonium toxicity. Chlorosis is lessened or eliminated by combining with Sus-tane. Dilute solutions spoil within 10 days.

Kimitec Espartan Liquid 2.0-3.03-2.6

Espartan is a plant extract fertilizer made from fermented sugar beet molasses. Some plants develop interveinal chlorosis due to ammo-nium toxicity and growth medium EC is rather high. Chlorosis and EC are lessened or eliminated by combining with Sustane. Dilute solu-tions spoil within 10 days.

Sustane Granular 8-4-4 Granular slow-release fertilizer made from turkey litter, feather meal and potassium sulfate. Release time is 45 days, but nutrients mayrun out a little sooner. Excellent fertilizer to combine with liquid organics, especially those with no phosphorus or potassium. OMRI listed.

Nature’s Source Liquid 3-1-1 Despite the low nutrient analysis, Nature’s Source is currently the best liquid organic fertilizer. It’s made from oilseed extract. Containerhas dilution rates expressed in familiar terms for greenhouse growers. I’ve seen no foliar chlorosis yet with this fertilizer. Nature’s Sourceis widely available and a great improvement over its predecessor Pinnacle. OMRI listed.

Verdanta Eco Vita Granular 7-5-10 I’m currently testing this granular slow-release fertilizer. It has a release rate of 100 days. The granules are composed of bone meal, soy-bean meal, cocoa shell meal, feather meal, and fermented sugar cane and sugar beet molasses. I see potential for this one. Availablefrom SHS Griffin. OMRI listed.

Verdanta PL-2 Liquid 2-0-6 I’m currently testing this fertilizer made from fermented sugar cane and sugar beet molasses. It should be a good supplement to use incombination with other organic fertilizers low in N or K. Available from SHS Griffin. OMRI listed.

Ferti-Nitro Plus Solublepowder

13.6-0-0 I’m currently testing this fertilizer as a supplement to use in combination with other organic fertilizers low in N. It’s made from hydrolyzedsoybean protein and is soluble. Google this one on the web. OMRI listed.

Organic Fertilizers Evaluated or Currently Under Trial at UMass Stockbridge School

27

3. Nutrient disorders. Plants maydevelop an overall light green oryellowed color caused by a gen-eral nutrient deficiency or, morelikely, just N deficiency. For exam-ple, if Sustane is used alone, thesymptoms might occur about 45days after planting, the end of itsrelease time. This can be pre-vented by applying an organicliquid fertilizer supplement about30 days after planting.

Interveinal chlorosis some-times occurs about halfwaythrough crop time if plants arefertilized with some liquid or-ganic fertilizers alone starting atplanting. This chlorosis is mostlikely caused by an accumulationof too much ammonium-nitrogenin the plant, so-called “ammo-nium toxicity.” Most greenhousecrops do best with a combina-tion of ammonium and nitrate ni-trogen. Unfortunately, organicfertilizers generally don’t containnitrate-nitrogen. The best ap-proach is to rely on Sustane asthe sole source of nutrients forthe first month after planting and

then start applying Nature’sSource or another liquid organicfertilizer. 4. Organic fertilizer effects ongrowth medium soluble salts(EC). Sustane is a slow-releasefertilizer and its use results in lowEC, and potentially a deficientlevel after 45 days. As for the liq-uid organics, at the same N level,the lowest EC results from Na-ture’s Source (similar to chemicalfertilizer) and then Bombardier.Espartan results in an EC signifi-cantly higher than the other liq-uid organic fertilizers, whichmight be an aggravating factor inammonium toxicity. In short, fromthe standpoint of EC, Nature’sSource is the best. 5. Overcome reduced sizecaused by organic fertilizers.Many growers who’ve used or-ganic fertilizers have observedsize reductions compared towhat they’re used to with chemi-cal fertilizers. Some growers say“raise the rate (ppm)” of organicsto compensate. If you’ve donethis and it works, carry on! Other-

wise, give it a trystarting with in-creases of 20%at a time. In-creasing therate in 20% in-crements islikely to be par-tially success-ful, but becauseof a nutrientimbalance, ammonium toxicityor some unknown factor, resultsmay be disappointing or worse. 6. Plant species-specific re-sponses. It seems that plants mayrespond differently to organic fer-tilizers. At this point in the devel-opment of organic fertilizers forcommercial greenhouse use, usethem with caution on plants youknow have exacting nutrient re-quirements or those prone to fo-liar chlorosis. Fertilizers shouldalways be tried first on a smallnumber of plants. 7. Best uses. The fertilizers dis-cussed in this article are probablybest for short-term crops of lessthan six weeks duration when en-

vironmental conditions are mostfavorable for plant growth (e.g.,April to September). Beddingplants, herbs and vegetable trans-plants are good candidates fortrying organics. Assuming theplants are of good quality andcolor, reduce or stop using thefertilizer within a week or two ofplanned marketing. This practicewill reduce the chance of ammo-nium toxicity symptoms.

DOUGLAS COX is Associate Professor ofGreenhouse Horticulture at theStockbridge School of Agriculture for theUniversity of Massachusetts in Amherst,Massachusetts.

Ammonium toxicity on petuniawith high levels of some water-soluble organic fertilizers.


28

Across the country, tomato growers areshifting their pest management strategiesto incorporate biological controls into themix. Reasons for adopting a more “bug-eat-bug” approach vary from protectingthe health of their family and workers,maintaining the vigor of bumblebee polli-nators or maximizing the market value fortheir crop by ensuring their fruit is grownin an environmentally responsible way.And avoiding the sweaty mess of spraygear in the summer is an added bonus.Regardless of the rationale, bios can beused easily, cheaply and effectively with afew phone calls, in addition to a thoroughscouting regimen.

Most growers, thankfully, only en-counter one or two of the pests that candecimate tomatoes in hoop houses orgreenhouses. They likely lock horns withthese same critters perennially andthere’s always the possibility of develop-ing new pest problems. That’s whatmakes a grower’s life interesting, anyway.Roughly speaking, the key pests oftomatoes are aphids, thrips, spider mitesand whiteflies, which commonly rear theirugly little heads in the same order. Thereare no guarantees with pest control, soit’s a loose chronology. But before we gointo too much detail about ways of killingthem, a brief interlude about sanitation.

We’re all tired of hearing about the im-portance of sanitation and I really don’twant to beat a dead horse. That said, theseverity of your pest problems this year istied to the amount of pests you’ve car-ried over from last year. Aphids andwhitefly persist often at undetectable lev-els on weeds and greens, spider mitesstay dormant on debris and structuresand thrips live everywhere—on weeds in-side and near the structure or in the soil.In addition to simply cleaning your hoophouses and greenhouses, consider solar-izing them, too. Simply close everything

up between crops and let the sun bakethe house for a week or so. That’ll killmany of the pests that were hanging outon your previous crops. And if you weregrowing any winter crops, chances arethose pests are aphids.

ADIEU TO APHIDS For aphid control, Aphidius parasites areyour first responders; call your biocontrolsupplier at the first sign of aphids. Aphid-ius are little wasps that lay their eggs in-side young aphids. Those aphidscontinue to live and grow for another sixto 10 days, after which they swell into agolden brown, papery aphid “mummy.”Seeing as the most common aphids en-countered on tomatoes are green peachand potato aphids, the two parasites in-volved here are Aphidius colemani and A.ervi, attacking the former and the latteraphids, respectively. The 2-mm-long A.colemani completes its life cycle in twoweeks, while the 4-mm A. ervi takes aweek longer. Though they develop moreslowly than their aphid hosts, one femalewasp can kill hundreds of aphids.

Judson Reid, the Senior ExtensionAgent with Cornell University’s VegetableProgram, suggests, “Once temperaturesare dependably above the 40s (F), I liketo release a mix of [Aphidius] parasites.”

Aphid parasite mixes are more expen-sive than those targeting a certainspecies, but Judson says, “We lose too

much time trying to get the aphids identi-fied.” But with a good shot from a smart-phone camera, some savvy growers canget an ID the same day. Aphid parasitesare shipped inside their mummies, sokeep the vial closed until you see thatsome wasps have emerged. Release atleast one wasp per 10 sq. ft. weekly orbiweekly (depending on temperature andaphid population) three times. As withmany winged bios, these wasps are at-tracted to bright lights and should be re-leased at dusk.

By April and May, the aphid midgeAphidoletes aphidimyza is a useful com-pliment to the slower-acting parasites.Released at a rate of one to 10 midgesper 10 sq. ft. for three consecutiveweeks, the midges can bring even estab-lished aphid populations under control.Not surprisingly, the more aphids youhave, the more midges you should planon releasing. If your aphids are undercontrol by June, usually enough preda-tors will join the party from outside tokeep cool weather-loving aphids underwraps until frost. Of course, the warmseason brings plenty of its own challenges.

TA-TA TO THRIPS With warmer temperatures, the life cyclesof other pests, like thrips, speed up, al-lowing even low populations to explodeseemingly overnight. But don’t worry—they’ve got a bug for that. According toJudson, “I would suggest people startwith cucumeris and treat transplants inthe propagation house rather than afterplanting out. It’s inexpensive enough touse preventatively and it’s likely to providesustained control.”

Judson goes on to say, “Two releasesof cucumeris have been enough to knock our thrips population down to undetectable.”

Pest Management

Biocontrols for Tomato Plants

The best parasitic weapons to use to defend your tomato crops. by SCOTT CREARY

29

Cucumeris are predatory mites thatarrive amongst wheat bran, which hostsa prey mite that the cucumeris eat untilthey disperse onto plants. These preda-tors aren’t picky eaters, but they eatnewly-hatched thrips—the only thrips lifestage small enough for the little mites totackle. When thrips hatchlings arescarce, cucumeris will munch on pollen,broad mites and spider mite eggs, allow-ing predators to establish long-term.You’ll want to release them at least twiceat two-week intervals. Once sprinkledonto the foliage, the mites disperse out ofthe bran on their own. To make thingseven easier, Judson offers, “Start bytreating the transplants in the propaga-tion house before planting out.”

To be on the safe side, you can re-lease rove beetles (Dalotia coriaria) or thepredatory mite, Stratiolaelaps (=Hy-poaspis), which will eat thrips when theydrop to the ground. The former, beingflight capable, can colonize large areasquickly and are used for structures withsoil or gravel floors. Stratios are moreuseful for localized introductions, liketomatoes grown in bags of media or inseedling trays. Both critters are intro-duced only once, at planting, and will re-main all year. Just sprinkle them on thesoil near the plants at a rate of 2 bee-tles/10 sq. ft. or 12 to 25 mites/sq. ft.Because adult thrips live as long as fourweeks, you’ll continue to see them for awhile after introducing bios, but the skiesstart to clear thereafter. Once your thripscontrols are in place, it’s time for an evenmitey-er task.

SO LONG TO SPIDER MITES I’m speaking, of course, about spidermites. Difficult to detect on hairy tomatoleaves, mites can explode to biblical pro-portions during a week of hot, dryweather. Rather than straining your eyeslooking for mites on your tomatoes, trysome indicator plants—those plants thatshow pests early and easily. Bush beansare cheap and easy indicators for spidermites. Tiny, white pinpricks (stippling) areclearly visible on the upper side of theleaf, so monitoring the beans is a cinch.One bean plant per 200 sq. ft. is plenty.You’ll want to have them up and growingby mid to late April, or a few weeks be-

fore you’ve historicallyspotted your first mites.Then watch those beanleaves for spider mitedamage. If you releasedcucumeris earlier in theyear, you may not seeany spider mites at all,but luck favors the prepared.

As always, make thecall to your biocontrolsupplier at the firstsighting. “If someonehad a mild spider miteproblem, I would rec-ommend several re-leases of Persimilis,”suggests Judson.

Persimilis are preda-tory mites that can stickaround long-term, pro-vided the beans con-tinue to host spidermites. You’ll want to re-lease them at a rate ofone mite per squarefoot every week for atleast two weeks. Afterthe predators establish,it’s likely that you won’tbe able to find spidermites anywhere but onthe beans, as the pred-ators pick off the fewspider mites they findon the tomato. Thebean plants are a greatplace to assess thenumber of spider mitesper predator and decideif the predators are ingood balance with thepest.

Predatory mites aredistinguished from theirprey by their teardropshape, cream to red coloration (nevergreen) and their speed, as they ziparound on the leaves while spider mitesmove slowly, when they move at all. Gen-erally, a ratio of 10 spider mites perpredatory mite is safe, while 20 spidermites per predator indicates anotherpredator release is in order. Keep youreyes on the lower leaves, where spider

mites are most numerous, along with ourlast pest, whitefly.

WAVING GOOD-BYE TO WHITEFLIESWhitefly adults, with their erratic flightpatterns and habit of flying up people’snoses, often catch the scout’s attentionbefore translucent green immatures. >>>

Spider mite predators are commonly sold with vermiculite to main-tain ample humidity in shipping. Sprinkle the contents of the bottleonto infested plants and leave the bottle and cap in the plants soremaining predators can disperse into the canopy.

Aphid parasites are shipped still inside their aphid “mummies.”Keep the bottle in a warm, humid, shaded place overnight or untilyou see adult wasps in the bottle before releasing in the evening.

30

If you catch them right out of the gate,the prognosis for biocontrol is good.

“It’s so easy,” says Carol Glenister,owner of IPM Labs, a biocontrol supplier.“It’s just four weekly introductions of par-asites at the first sign of whitefly. It’s inex-pensive, it’s fast and it’s effective.”

Release one wasp (Encarsia formosa)per square foot at each introduction andyou’re good to go. Just like with spidermite predators, check the pruned leavesbefore discarding them. Whiteflies withparasites developing inside turn black, soany leaves with blackened whitefly pupaeshould remain on the plant for severaldays longer.

SOME FINAL TIPS Perhaps the biggest change when shift-ing to biocontrols needs to happen inyour mind. Bios will not eradicate pests,nor should you want them to. They pro-vide gradual and constant pressure onpests, keeping pest levels at consistently

low levels. So expect to see a few un-wanted visitors every so often, especiallywhen they start coming in from outside.Calming the knee-jerk reaction to anypest sighting is a slow process, but you’llrelearn what thresholds work for yourbiocontrol program pretty quickly. Shouldpests exceed that level, you’ll need touse other tools at your disposal.

Pesticides and bios aren’t mutuallyexclusive. In fact, due to the increasedadoption of integrated methods, manynew pesticides are target-specific andcompatible with many beneficial critters.Check with your biocontrol supplier toensure that your chemicals are biocon-trol-friendly and if their use is warranted.Keep in mind that chemical control takesa back seat to biological control onceadopted and should be used as a last re-sort. But you can rest assured that thisisn’t your biocontrol supplier’s first rodeo.Because tomatoes are such widespreadhigh-value crops, tomato biocontrol has

been fine-tuned over many decades andwe know what to expect by this point.

For most growers, not needing tosweat it out under layers of Tyvek andrespirators isn’t a tough sell. Talkingabout your biocontrol program resonatesextremely well with the public, especiallygiven how educated and inquisitive con-sumers have become about their food.Bumblebees will buzz your praises, whilenaturally-occurring beneficial insects—including pollinators—will become moreabundant through the year. Over thecourse of the year, you’ll see healthier,more robust and productive plants, asthey won’t be stressed by spray phyto-toxicity.

And finally, your wallet—especiallywhen labor and equipment costs are fac-tored in—will be healthier and more ro-bust, too.

SCOTT CREARY is an Entomologist at IPM Labs, Inc.in Locke, New York.

Pest Management


31

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Growing plants using a hydroponic system isn’t new; it has along history, which many believe started in the city of Babylonwith the famous hanging gardens. Commercial hydroponic pro-duction started in the 1940s and today, due to the tremendousprogress made in technology, every aspect of the operation canbe computer-controlled (i.e., temperature, humidity, carbon diox-ide, light, fertilizer, etc.).

Growers venture into hydroponic production for a number ofreasons, which include year-round local production, reducedcarbon footprint and avoiding root diseases that are often limit-ing in field and greenhouse production. With the ability to controlmany parameters associated with plant growth, shouldn’t it bepossible to have the perfect crop every time? Unfortunately, thisis not the case.

WHAT CAN GO WRONG WHEN GROWING HYDROPONIC CROPS?Although the diversity of root diseases observed in hy-droponic production is less than in soil-grown sys-tems, root diseases associated with Pythiumspecies are still a problem for most crops.Once the organism is introduced into thesystem, disease can development rap-idly and result in significant crop loss.This is particularly true with closed hy-droponic systems and can happen inmost crops. Professor Emeritus GaryMoorman from the Department ofPlant Pathology and Environmental Mi-crobiology at Penn State University said,“In my experience, just about any plantgrown hydroponically is at risk to certainspecies of Pythium.” He said that he’d re-cently detected Pythium aphanidermatum in hy-droponically grown tomato, lettuce, spinach and arugula.

Professor Emeritus Michael Stanghellini of the University ofCalifornia—Riverside and Gary agree that if a grower gets a dis-ease outbreak, it’s importance to accurately identify the organ-isms involved and “identify to the species level.” For assistancein pathogen identification, growers are encouraged to contacttheir regional co-operative extension educator. There are manyspecies of Pythium found in greenhouse situations, but Pythiumaphanidermatum and Pythium dissotocum are the most com-monly observed, serious plant pathogens in hydroponic sys-tems. Why is it important to know? The rate at which Pythiumspecies populations develop is affected by temperature, with P.

aphanidermatum being the prominent species at 73 to 80F (23to 27C), whereas P. dissotocum is prominent at 62 to 73F (17 to23C). Michael said that he’s even seen Phytophthora species inhydroponically grown lettuce, but “it is often not recognized asthis,” he said.

WHY IT’S A PROBLEM IN HYDROPONIC SYSTEMSUntil relatively recently, Pythium species were considered fungi.Even though their mycelial growth and nutrition resemble fungi,their morphological characteristics and findings from molecularstudies support the notion that they’re more closely related towater molds. Both the open and closed hydroponic systems cansupport rapid Pythium growth, although it’s generally thoughtthat the closed system is more conducive, as it’s recirculatingthe nutrients.

Oospores are the main survival structures of P. aphaniderma-tum and P. dissotocum. They can germinate to form germ tubes,

which then may infect roots.Oospores produce sporangia thatbear thin-walled vesicles from

which zoospores are released (Figure 1) and arethe big problem. Zoospores are motile, unicellu-lar, propagative bodies measuring in the case ofP. aphanidermatum 14 micrometers long and 9micrometers in diameter (approximate). Thismotile phase can last for up to 24 hours dur-ing which time through chemical signaling thezoospore locates a root, encysts and infects it.The reproductive capabilities of thesezoosporic pathogens are enormous, which isone of the main reasons that an epidemic can

occur so very rapidly under hydroponic conditions.

HOW TO COPE WITH PYTHIUM IN HYDROPONIC PRODUCTION

Keeping Pythium species out of a hydroponic system is clearlymost desirable. Growing varieties with resistance to Pythiumspecies would be ideal, but currently, no vegetables varietieswith such resistance suitable for hydroponic production areavailable.

Starting with disease-free transplants is important and pro-ducers growing their own transplants can have greater controlover the production than if they buy in transplants—particularlyas plants on delivery may appear healthy and yet be infectedwith Pythium at the initial stage of infection when there are nosymptoms. (The grey-brown root coloration doesn’t appear untillater.)

Pest Management

Hydroponic Production & Pythium

You can still experience root rot even when you’re not growing in soil. Learning the symptoms and how to prevent Pythium can be a crop lifesaver.

by HELEN MARGARET GRIFFITHS

32

Figure 1. P. aphanidermatum zoosporesreleasing from vesicle.

Photo

credit:

Eric Carr, Cornell University.

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WHAT ARE THE ENTRY POINTS FOR PYTHIUMSPECIES INTO A HYDROPONIC SYSTEM?There are a number of possible ways the organism can enter ahydroponic system. Soil is a way Pythium species spread, andeven though hydroponic production is a soil-free growing sys-tem, soil can still be brought into a facility if care isn’t taken withcleanliness of foot wear, clothing and equipment.

Surface water, such as rivers, ponds and reservoirs, are majorsources of Pythium inoculum and should not be used in hydro-ponics. Well water is usually considered safe. Gary says thatchlorinated water is by far the most commonly used. Having acourse filter in place is good because, according to Gary, remov-ing particles is important, as from his experience, Pythium canbe associated with the particles—particularly in ebb-and-floodsystems.

Fungus gnats (Bradysia spp.) and shoreflies (Scatella stag-nalis) are common in greenhouses and it’s been shown that theadult shorefly can be involved in the transmission of P. aphani-dermatum and, therefore, insect control is important.

WHAT ARE THE OPTIONS IF AN INFECTION OCCURS? Rarely in hydroponics are growers able to consistently producecrops entirely by avoidance of Pythium; usually a number of dis-ease-control methods have to be implemented to try to controlwhat can become a challenging situation if a Pythium epidemicbecomes established. And as Michael said, “There is no cure.”Searching for fungicides isn’t going to result in a grower findingproducts, as there are none registered for use in hydroponics.

Biosurfactants may be useful for control. Michael, who spentmany years researching them, said that as long as the zoosporepopulation is low, such products can be effective. Gary alsoworked with them in ebb-and-flood systems and agreed thatthey work, provided that infection isn’t being caused by

mycelium. The biosurfactant Zonix is la-beled for use in most states (Californiaregistration expected fall 2015) for hydro-ponics and is OMRI approved.

Eliminating zoospores can be accom-plished by ozonation, sonication, heat,UV and filtration. Some systems are cheaper to implement thanothers and UV requires iron to be added back into the nutrientsolution. David de Villiers, a research scientist at Cornell Univer-sity’s controlled environment agriculture department, reminds thegrower of the real problem when he said, “Killing Pythium is veryeasy, but you have to be able to get at it. Zoospores in the nutri-ent solution can be eliminated with any of the techniques, buttrying to eliminate the pathogen from the plants is not possible.”

At this point, the grower has to provide supportive care to theplants and reduce further stress if a crop is going to be obtained.Oxygenation is one of the few practical measures available togrowers when root rot is well advanced. Temperature of nutrientsolution affects the concentration of dissolved oxygen availableto the roots of the plants. As the temperature of the solution in-creases, the concentration of oxygen declines and, therefore,keeps nutrient temperatures as low as possible—which is criticalfor the wellbeing of the plants, particularly if the roots have beencompromised by infection.

Using temperature of the nutrient solution to regulate the rateof Pythium development is a possible control method dependingupon the crop. David says that their approach at Cornell with re-search using baby-leaf crops is to grow so quickly and at a lowenough root zone temperature that the P. aphanidermatumdoesn’t have time to reproduce itself. This works for crops likespinach, but lettuce growth falls when temperatures fall below75F (24C). Purchasing specific equipment for temperature regu-lation may be outside of the budget of a small producer, but

Figure 2. Roots of hydroponicallygrown sweet pepper (Capsicumannuum) seedlings infected withPythium aphanidermatum. Close-upof healthy roots (far left) besideroots showing the progression ofthe disease over time.

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as Michael said, “Thereare plenty of innovativegrowers who would beable to design and buildtheir own cooling system.”

Optimizing the tem-perature of the nutrientsolution for hydroponicplant growth is also im-portant for producinghigh yields from hydro-ponics. Coralie Sopherat the University ofGuelph in Canadademonstrated that inhigh temperature-pre-

disposed sweet pepper plants to P. aphanidermatum (Figure 2).

DISMANTLING AND CLEANING Views vary on how often a hydroponic system should be cleanedand this will need to be determined by the individual producer,type of system and level of disease being experienced. Some ofthe large tomato producers have a yearly/bi-yearly clean as partof their operating procedure. The job is labor intensive and will

generate a large volume of waste liquid. Choice of cleaners aremany, but David says that they use 70% alcohol for sanitization.Even though Clorox works well, they find it unpleasant, and someother products can leave residues.

PREVENTING PYTHIUM Start with healthy plants with robust root systems and be ex-tremely diligent about cleanliness. In addition, optimize the grow-ing conditions for the particular crop aiming to eliminate stress.

Vermicompost has been used to increase the vigor of soil-grown plants and at least one hydroponic grower found it helpfulin producing basil in floating beds with improved resistance toPythium (Figure 3). A research project called “Using Vermicom-post to Improve the Profitability of Hydroponic Spinach Produc-tion” funded by USDA SBIR is underway at the company WormPower (www.wormpower.net) in collaboration with Cornell Univer-sity and may generate information useful to producers.

Each producer will need to determine which methods bestsuit their situation, as all treatment methods have pros and cons.

Please note: The specific directions on fungicide labels must be followed and supersedeany statements in this article if there’s a conflict. Any reference to commercial products,trade or brand names is for information only.

HELEN MARGARET GRIFFITHS is a freelance writer in the Finger Lakes area ofCentral New York.

Pest Management

Figure 3. Roots of basil plants grown infloating beds. Plants grown with Worm Power(right) showed significant improvement inroot structure, basil quality and quantity.

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