\^0L. 9, NO. 9 The University of Arizona Cooperative Extension SEPTEMBER1998

Cochise County Master Gardener

The University of Arizona and U.S. Department of Agriculture cooperatino.

Garden Basics:High Desert Garden

Fair

Join the Cochise County MasterGardeners Association on our next

adventure — The High DesertGarden Fair, Saturday, September12, 9:00 am to 3:00 pm, at TheUnivereity of Arizona SierraVistaCampus, 1140 N. Colombo. Freeto the public, the fiiir will provideinformation and products to makeoutdoor and gardening lifestylesmore enjoyable.

Among foe numerous vendors attending will be Bisbe^ACE Hardware Nurseiy, Arizona SoapCompany, Dimnond JK Nurseiy,Desert Blossom, Kazzam NaforeCenter, San Pedro House-Booksand Gifts, Recycling Info Boofo,Sierra Vista Area Gard»iers

Club, Spadeft)ot Nurseiy,Southeastern Arizona Bird Observatory, Sustainable Systems Support, Third World Fkmd Arts,Tunwr Trucking Landscape Materials, Hie University of ArizonaBookstore, Valley Rentals, Water-Wise, Zamp County Nursery,Dick and Jane's Vqgetable Stand,and Cochise County Master Gardeners Association with water

probes, t-shirts, and a DesertLandscaping CD-ROM for sale.You will also be able to tour foePlant Sciences Center located atfoe U. ofA.canq)us.

There will be three fiee semi

nars during foe day. Leam aboutProper Planting Techniques from9:30 am to 10:30 am. During foepresentation. Master Gardner,DeForest Lewis, will show youhow it's done by planting a planton foe U. of A. grounds. SandyAndersrm will talk about benefi

cial snakes for foe garden in herRapturous Reptiles seminar from11:30 am to 12:30 pm. There willbe snakes on display. Frcsn 1:30pm to 2:30 pm, leam about nativeplants ofthe highdesertat foeNatives - Naturally} seminar. Additionally, foe Sierra Vista AreaGardeners Club will be givingtheir own gardening presentationsthroughout the day at foeir booth.Leam how to collect and save

seeds frcsn foe garden at 10:00 -10:30; 12:45 - 1:15; and 2:30 -3:00 and plant propagationtechniques will be demonstrated at10:45 -11:15; 11:45 -12:15; and12:45 -1:15.

See you there!Chert MeltonMaster Gardener

Meeting ReminderCochiseCounty Master Gardoi-

ers Association meets September2, 5:00 pm at foe Mona BishopGallery Room at foe Sierra VistaLibrary. Discussions will include:foe High Desert Garden Fair, foeSan Pedro House project. National Publics Lands Day-foeBuf&lo Soldier Trail project, andfoe 1999 High Desert Gardening& Landscaping Conference. AllMaster Gardeners and Associates

are invited to attend.

Fall Plant SalesOctober3&4

Tucson Botanical Gardens

TcfoonoChul Park, TucsonDesert Survivors, Tucson

October 16 - November 1

BoyceThompsonArboretum,Superior

October 24 & 25

Desert Botanical Garden, Phoenix

1140 N. ColombOt Sierra Vista, AZ 85635(520) 458-8278, Ext. 141

Cochise County Cooperative Extension450 HaskeU, Wiiicox, AZ 85643(520)384-3594

TtiE Victual

Cacccncc-

How Much Water is Enough?

When we finished last month, wehad discovered how to find values

for potential evapotranspiration(ETo) using AZMET data. Thismonth I want to discuss how we

can put that information topractical use. Specifically, I wantto answer the question; How muchwater is enough? Before I continue,however, I want to emphasize thatmy purpose is not to explain a "bythe numbers" system for wateringyour plants. Rather, I want you todevelop a ^ for how much waterit takes to keep your plants happyand healthy.

The ETo values we learned

jfoout last month provide the basisfor determining how much waterhas been removed by evtqro-transpiration. These numbers showthe predicted amoimt of water ininches that a reference crop (turfgrass) would use during a certainperiod of time. Of course unlessyour plants h^pen to be the sameas die reference crop, they may notuse water at die same rate as the

reference, So you must multiply thelisted ETo values by a correctionfactor called a crop coefficient topredict how much your particular

plants would have used. A goodsource of data on crop coefficientshas been compiled by die UnitedNations Food and AgricultureOrganization (FAO) and can befound at:http://agen.tamu.edu/wqit/petaiet/tools/crop/cropcoe2. html

The crop coefficients shown inthe FAO reference even take intoaccount the st^e of growdi of thecrop—initial growth, mid-seasongrowth, and late season growthbecause plants use water atdifferent rates throughout their lifecycles. Table 1 shows a fewsamples of the kind of dateavailable at the Web site.

Suppose you are growingtomatoes. According to the FAOfigures, the crop coefficient fortomatoes at mid-season is 1.2- Thatmeans that you must multiply theETo values obtained from theBonite AZMET site by 1.2 in orderto calculate how much water yourtomatoes are using. For wcample,the ETo values given for die firstweek of August at Bonite areshown in the second column ofTable 2 and die corrected valuesfor tomatoes are shown in the thirdcolumn.

What these numbers are tellingus is diat during the first sevendays in August 2.11 inches ofwater would have had to be added

to your tomatoes to make up forwhat was lost due to evapotranspiration. If any rain had fidlteiduring that period, you couldsubtract that fi'om the total. In thecase of the Bonite AZMET site, atotal of 0.02 inches of rain fellduring the period so <Hily 2.09inches of water irrigation waterwould have be^ required to makeup for what was used. To get anidea of how many gallons arerepresented by 2.09 inches, wehave to do a litde arithmetic.

Onesquare fixit is 12 inches on asideand represents 12 inches X 12inches = 144 square inches of area.To cover that area with 1 inch ofwater, requires 144 square inchesX 1 inch = 144 cubic inches ofwater. Since there are 231 cubicinches of water in a gallon, we cancalculate that 144 cubic inches ofwater represents 144 cubicinches/231 cubic inches per gallon= 0.62 gallons of water. In otherwords, it takes a litde over one-hdfgallonof water to supply 1 inchofwater to a square foot of soil.

Since my tomatoes are planted in4 feet by 4 feet squares, eachsquare covers 16 square feet.Supplying 2.09 inches of water to asquare would require 16 squarefeet X 2.09 inches X 0.62 gallonsper square footor about22 gallonsof irrigation vrater. This of courseassumes that all of the water I

delivered was

available to the

tomato plants.Does this mean

that if I had poured22 gallons of wateron each of mytrnnato squaresafter a week,without watering

(Continued on next page)

Beans, green 0.40 1.00 0.90

Carrots 0.50 1.10 0.80

Celery 0.35 1.10 1.00

Com, sweet 0.40 1.15 1,05

Cuciunber 0.35 0.95 0.75

Eggplant 0.40 1.05 0,85

Melons 0.40 1.00 0.75

Peppers 0.35 1.05 0.85

Radish 0,30 0.85 0.80

Tomato 0.40 1.20 0.65

Table 1. SomeRepresentativeValuesof Crop CoefRclents for Arid Climates

Page 2

my tomatoes would beperfect? Ofcoursenot. First, all ofthewater I supplied would not have reached the thirsty roots ofmy tomatoes. Second, my tomatoes might have expired ofthirst if I had not watered them for a week. And third, the soilin my garden probably has different water holdingcharacteristics than the soil at Bonita so might require greateror lesser amounts of water than the ETo values wouldindicate. What the numbers give me is a place to start. Ishould apply this much water and watch to see what happens.If the plants wilt, then I need to increase the amount a little. Ifthe soil remains soggy, I can probably decrease the amount alittle.

Hopefully this discussion has given you a little insight intohow much water is enough. Until next month, happy surfing.

Gary A, Gruenhagen, Master Gardener (ff%ienha@sinosa.com)

1 Aug 0.19 0.23

2Aug 0.20 0.24

3 Aug 0.24 0.29

4 Aug 0.29 0.35

5 Aug 0.28 0.34

6 Aug 0.28 0.34

7 Aug 0.27 0.32

Table 2. Adjusted £T Values for Tomatoes

smwMBeRneMiNpats

> Keep on watering!> You can always plantsomething - try cool seasonveggies> Start shopping for bulbs(Bulbs for Southern Arizonabulletin is available from theCooperative Extension offices)

Cuttings'N'

Clippings>• Cochise County Master Gardeners meet the first Wednesday ofeach month in the Mona Bishoproom at the Sierra Vista Library,5:00 pm.^ National Public Lands Daywill be celebrated in Sierra Vistaon September 26. Many activitiesare platmed. Contact City Hall fordetails.

San Pedro HouseUrban Wildlife Habitat

Demonstration

Landscape Project

TheBureau of Land Management(BLM) received a grant tolandscape the area arotmd die SanPedro House, part of the SanPedro Riparian NationalConservation Area. The purposeof the grant was to provide abeautifully landscaped area thatwill reduce dust, require nowatering once established, usenative plants, be beneficial towildlife, and to serve as ademonstration garden where thepublic can get ideas. The CochiseCounty Master GardenersAssociation received a letter inJune requesting their assistanceand they haveprovidedBLM witha final landscape design. Theplants are being ordered and thegrounds are being prepped forplanting. On September 19 & 20,

planting will begin at 6:30 amtmtil it's too hot to continue! Ifyou would like to volunteer,please, bring whatever tools youmay have to include a shovel,rake, pick, watering can, andwheelbarrow. And don't forgetwater, sunscreen and a hat. A shortseminar will be pre sented onplanting techniques and why theplmits that will be used werechosen and their attributes.

This project is open to everyone—^non-master gardeners andMaster Gardeners alike so pleasecome join us for a weekend offun!The dedication of the site will takeplace September 26th for NationalPublic Lands Day. For moreinformation contact the Cooperative Extension Office.

Robert E. Call,Extension Agent, Horticulture

Carolyn Gruenhagen,Newsletter Editor

ofCw^^ve Extensim work, acts rfMay 8and June 30,1914, in cocpoation with the United States Deiiailmein Agricuhuie, James A. Christaison.ExtensK^ Collie ofA^cultuie. pe Umvosity rfArizona and Arizona Counties coiqiwatins. The Univeraity ofArizona College of Agriculture is:

..^1(^rtunify employe auth^ed to povide researdi, educational information and other services only to individuals and institutions foat function wifoout remud to serace, religion, coIot, national ongtn, age, Vietnam Era Veteran's status, ordisability. ®The information given herein is supplied with the understanding that no discrimination is intended and no endoreem^t by Cooperative Extension is implied.Any pioducts, services, or organizations that are mentioned, shown, or indirectly implied in this publication do not in^ily endorsement by the Uhiveisity ofArizona.

Page 3

Monsoon RainsHave HiddenBenefits For

PlantsThe loud crackle and thunderous

boomoflightningis now a familiarsound as our Monsoon season is in

full swing! But have you evernoticed that our summer stormsbring more than just much neededrainfall? The desert, and plants ingeneral, just seem greener after athunderstorm. And the reason: withthe rain comes a wealth of lifegiving plant nutrients.

Lightening is a potent fertilizingagent. Everytime it strikesnitrogenin the atmosphere is combined withhydrogen or oxygen to formammonium and nitrate, two formsof nitrogen. Thenitrogen thengoesinto solution in atmosphericmoisture and is washed to theground in rainfall. Plants diaiabsorb nitrogen from the groundand utilize it for growth. Since it isa keyconstituent in chlorophyll, thegreen pigment of plants, nitrog^causes a greeningofthe plant.

Physicists estimate that roughly250,000 tons of nitrogen areproduced by about 1,800 thunderstorms that occur on Earthevery day. Our summer thunderstorms can release significantamounts of nitrogen for plantgrowth here in Tucson. Thatcauses a significant part of thegreming ofplants we notice after astorm. But other constituents ofrain also contribute to thisgreening!

In theory, rain water is pure. It isfonned from evaporation of moisture largely from the ocean, butalso fix)m inland bodies of water,the soil, plants, and even animals.Condensation returns it to earth;but not before it picks up somehitch-hikers. Sulfur is one of these.

Page 4

It is possible for rain to provide asmuch as 40 pounds of sulfur peracre per year. Less in our desertenviromnent, but still when therains come so to does die sulfur.

Sulfur IS an important constituentin the formation of plant aminoacids.

Dust is something we have noshortage of here in the Souttiwest,but dust although a nuisanceindoors can be beneficial. Dust is

often carried thousands of miles on

die upper air currents, and comesdown to card) during rain storms.

Dust carries with it a number of

mineral nutrients necessary forplant growth. It also containsbeneficial micro organisms whichenhance plant growth. Thesolubilized nutrients can quicklyinfluence the color of foliage.Micro organisrtu aid in thebreakdown of organic compoundsinto plant nutrients. They alsocreate symbiotic rel^onships withplant roots whichaid in the uptakeofnutrients. All diis translates into

a rapid "green-up" ofplants!The level of soil b^efiting

elements and micro organisms isrelated to the origin of such dust.Ashes from forest fires ccmtain

potash, an essentid plant nutrient.Debris from volcanos, vhich cantravel world-wide contains a wealth

of essential minerals for plantgrowdi.

The number of thunderstorms we

enjoy in the Tucson area arelimited, however the beneficialeffects of rainstorms can be

botded; or at least barreled, forlater use. Rainwater can easily betrapped and stored for later use.The easiest way is to attach barrelsto the down spouts from roofgutters. Large plastic garbage canswork well. Use a dark color, likegreen or gray, to keep the light out.Keep the lid on tight to ke^ outlight, bugs, and critters. This wiUkeq) the water fiesh and preventstagnation from algae and bacteria.Cut a hole in the lid, large enoughto put the downspout through andserd the crack with caulking or ducttape. A valved exit pipe at diebottom of the barrel allows you toattach a drip system or hose forirrigating plants. If you want, youcan connect several rain barrels to

collect more water. PVC pipiiigfrom die top of one barrel toanother will allow water to

overflow from the first barrel into

the next. You can connect a

number of barrels this way.Barrels can be screened with

shrubs ifappearance is a priority.During a typical Monsoon season,

the roof of an average size housecan collect as much as 4,000gallons of rain water! You cancollect as much water as you wish,dependingon the number of barrelsyou use. An overflow pipe wellallow the excess to escape. A ruleof thumb for the Tucson area is to

have one plastic trash container (32gallon capacity) for each 6 feetlength ofgutter.

Rainwater does have real benefits

for plants. So, if after the nextthuni^rstorm you notice everythinglooks greener; it's not yourimagination! It's just MotherNature working her special magic.

John BegemanExtension Agent, Pima County

(Editor's note; In addition to hisExtension duties, Begeman mites aweeklycolumnfor the Arizona Daily Star.This article is reprinted with the author'spermission.)

Late SummerReading...A Book Review

The Eye Witness Series ofGarden Handbooks

Publisher: DK Publishing, fee,, 95Madison Ave., New York, NY

I first noticed this series ofbooksat a Tucson discount store. Therewere several: Annuals, Perennials,Roses, and Herbs. Since then Ihave also s^n Garden Herbs,Trees, and Shrubs. Prices haveranged from $8.99in Tucson to the$15.00 to $20.00 rai^e locally.

The books are well organized,informative, and best of aU, a colorpicture of each species discussed isprinted on heavy, glossy p^rer. Ihave invested in two: Perennialsand Herbs. The herbs bookcontains pictures, descriptions andinformation on 700 herbs fromaround the world. It is aimedtoward people interested inmedicinal uses, but includesculinary infoimation. The bookstarts with illustrated informationabout each

part of theplant whichmay be useful.Two pageseach are

devoted to

roots, seedsmid fixiits,bark and

wood, leaves and stems, andflowers. Several pages are devotedto each category of use for herbs,such as cooking or healing. Eachdescription includes habitat andcoded information concerningwhich plant parts are used. Thephot(^;raphs are annotated so youknow what you are seeing.Characteristics of the plant areprovided, such as when and howmany blooms. Species with

multiple usefiil varieties m:egrouped^ with both gmieral andspecific information, andnumerousphotogr^hs. There are also small"filler" articles, such as drying orharvesting leaves. The GardenHerbs bode has fewer entries andleans more toward culinaryapplications.

The per^als book is similar,except tiiat the organization of thebook is keyed to plant size, bloomseason and color. This can be alittle fhistrating at first to thoseaccustomed to tiie WesternGarden Book listing by botanicalname, but the index is great andother qualities of the publicationquickly make upforminor changesrequired by the user. The colorpictures include multiple photographs ofvarieties ofmore popularspecies. Eadiplant description haslots of information in an uncluttered format.

Theonly major drawback I havefound is that the books aresomewhat specialized. You won'tfind trees and perennials in thesame volume. However, if you areconcentrating ononeaspect of yourgarden and need an informativewell-prepared reference, tiie Eyewitness publications I have seenare worth serious consideration.

GretchenKentMaster Gardener Associate

The Agent'sObservations

are my Afghan(Pinus eldarica)

^^iiHiPThe trees are deepwatered on a regular basis. Thereare no signs of damage from

insects or disease. What can I doabout tillsproblem?

tiie summer

witii hi^many

^. Jpine tree species willP^naturally shed some of

their older needles. However, ifthe new terminal growth is turningbrown, then some action needs tobe taken to remedy thesituation.Control: Normal, proper wateringshould continue throughout thegrowing season. Some tiiink thatthemonsoon rains produce enoughwater for good growth. This isusually not the ease. Rain isinconsistent both in timing andamount. Another wateringproblem is with larger pine trees.When yoimg trees are planted, adrip system or other wateringsystem is installed to supply theneeds of a young tree. Perhaps oneor two emitters are placednear thetrunk. This is sufficient while thetree is yoimg, but not as the treegrows older. Emitters must bedoubled iqi or replaced with higherflow emitters and spread outlaterally to encourage extendedroot growth. I have seen matureevergreen trees blown over by astorm when the ground was wet.Always the tree has had anunderdeveloped root system. Thecause was poor water applicationthat did not encourage extendedroot growth.

Mi*;!®

mm

IteSi

'mm.

ft months

have a Golden.J Delicious apple treellli irregular largeRwithmm

places the spotsare turning brown and

dying. Some of tiiese affectedleaves are falling to the ground.What is causing this and what canbe done to stop it in the foture.?

(ConUrmed on nextpage)

Pages

ARIZONA COOPERATIVE EXTENSIONU.S. DEPARTMENT OF AGRICULTURE

Cochise County450 S. Haskeli Avenue

WiUcox,AZ 85643-2790OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE $300

Address Correction Requested

£3L leafblotch, also called. ^ leaf spot or leaf drop.

Golden Delicious is' particularly suscepti

ble and this condition is restrictedto this cultivar and others with its"blood-line." This disorder ischaracterized by irregular necroticblotches in mature leaves that develop rapidly, usually within 12to 24 hours. The leaf fiist turnspale green and yellow andthen darkens to a deepbrown. The size of the affectedarea remains constant once visible symptoms appear. The size ofthe necrotic area is restricted bylarger veins which are not affected. Mature leaves, in the mid-shoot region, are usually affectedfirst. Young vigorous trees appearless severely affected than older.

more slowly growing trees. Leaffall can be rapid once symptomsoccur, sometimes within 4 to 7days. Severity of the disease varies greatly from year to year.V^iation can be great amongtrees in the same orchard or yard.Necrotic leaf blotch is a physiological disorder related to air temperature, light intensity, luid soilmoisture. It is most severe whena cool, rainyperiod of 4 to 5 daysprecedes several hot sunny days.A hormonal imbalance is thought

BULK^TEPOSTAGE & FEES PAID

USDA

PERMIT N(kG268

to be the cause since sjrmptomsare enhanced by gibberellin (aplant hormone that is needed forcell enlargement) and inhibitedby abscisic acid (another planthormone that causes leaf and fhiit

fall).Control: Zinc oxide appliedevery two weeks ftom bud breakuntil harvest is effective in reduc

ing disease incidences. Also,healthy, vigorous trees producedby good watering, fertilizing,fruit thinning, and pruning practices contribute to decreased inci

dences ofnecrotic leaf blotch.

Source: Compendium of Appleand Pear Diseases, 1991. TheAmerican Phytopathological Society, Page 88.

Robert E. CallExtension Agent, HorUculture