Spring 1996
Soil
utions
Vol.7,No.1 PublishedbyAgronomyUnit
Crop Diagnostics - Beware the Pitfalls
DeeAnnBenard, PlantPathologist
W
hena specialistgoesintothefieldand diagnosesaproblem,it
oftenlooks soeasy.But beware: diagnosing mostcropproblemsismoredifficult thansimplynoticingoneortwo symptomsinafield.Knowledgeofthe cropandvariety,fieldhistory,recent environmentalconditions,patternof theproblem,etc.arenecessary before evenattemptinga diagnosis.Looking forother, lessobvious,symptomsis alsoimportant,particularlyifthe initiallyobservedsymptom(s)canbe attributed to anumberofpotential causes.Knowingthesymptoms associatedwitheachofthepossible causescan help the novice
diagnosticianknowwhatelse tolook forwhenfacedwithaproblem.
Wind damagecanbeusedtoillustrate
someofthecomplexitiesofcrop diagnostics.Oneofthesymptomsof winddamageinbarleyislodging.But lodgingmayhaveother causes,such asphosphorus,potassiumorcopper deficiency,excessnitrogen,eyespot (alsoknownasstrawbreaker), oreven
haildamage.It isimportanttoknow informationsuchasthefieldhistory andthe recent environmental conditions.Askingtherightquestions can helpdeterminethecauseofthe problem. Questionstoanswerin this caseinclude:“Dorecentsoiltests suggestapossiblefertilityproblem?”,
“Hasitbeenvery windy?”,“Hasthere beenhail?”,“Hastheweather been coolandmoist,whichfavourseyespot development?”.Knowingtheother symptomsassociatedwith each possiblecause can help the
diagnosticianknowwhatelse tolook for: e.g.,isthereshattering?
(associatedwith wind);does the lodgingoriginatefrompointswell abovetheground?(associatedwith haildamage);dotheculms havea charredappearance?(associatedwith eyespot);isthereapurplepigment?
(phosphorusdeficiency);isthere excessivetillering?(potassium deficiency);oristhere lushgrowth?
(excessnitrogen),oristhestrawweak andtheheadsempty?(copper deficiency).
Accurate diagnosisisalsoimportant withproblemsthatareeasilyconfused withoneanother;thediagnostician especiallydoesnotwanttoconfusea harmlessproblemwithamoreserious one.Forexample,copperdeficiencyin barleymaybeconfused with eyespot, take-allorroot rotssuchascommon
root rot/seedling blightorbrowning rootrot.Carefulexaminationcan help intheir differentiation.Whiletake-all israreinAlbertabarley,eyespot/
strawbreaker,copperdeficiencyand someofthe rootrotsarefairly
common. Theycanbequitedamaging andcontrolmethodsvary.Asidefrom knowingthe varioussymptoms associatedwitheach problem, sometimesthere aresimplediagnostic teststhatcanbeperformedinthe field.Forexample,a diagnostic test to distinguish take-allfromotherroot rotsistowashthe rootsandstrip
awaytheouterlayers;in take-all,the centralvascularcylinderwillappear brownto black.
Oncethecauseoftheproblemis
known,thediagnosticianmustknow
theeconomicimpact.Forexample,a producermightnoticesomeplants thatdon’tlookquiteright.Howdoes heorsheknowit’saproblem?Fast andcorrectdiagnosisfollowedbythe appropriateactioncansometimes meanthedifferencebetweenagood cropandonethatisunsalvageable.It
cont’donpage2
This Issue
CropDiagnostics-Bewarethe
Pitfalls 1
KarnalbuntintheU.S. 2
FertilizingSpringWheat for
YieldandProtein 3
ComparingApplesand Oranges 4
Optimizing BarleySilage
ProductioninAlberta 5
TimetoControlWinter
AnnualWeeds 7
CaringforAlberta’s Air 7
FertilizingPeasinAlberta 8
IrrigatedBean Agronomic
ResearchinSouthernAlberta 9
Meetthe Specialist 10
“Don’tLeaveittoCleavers” 10
DearAggie 11
Liberia
AGRICULTURE,FOODAND RURALDEVELOPMENT
CropDiagnostics (cont’d) canalsomeanthedifferencebetween unnecessary,expensive chemical applicationandthesamecropquality andyieldwithout chemicalapplication.
Sometimes, thoughtheproblem might beimportant,nothingcanbedoneat thetime.It’s stillimportantto correctlydiagnose theproblem, becauseit’snotlikely togoawayon
itsown, andoftenpreventive measurescanbetakentoavoidfuture losses. Let’sexaminethepossible scenarios. Inthefirstexample,a potatogrowernotices afewpatchesof plantsalong theedgeof afieldthat havewater-soakedlesionsonsomeof theirleaves.Theweatheriscooland wet, withno changein sight.Should thisgrower beconcerned?Youbet!!
!
Thoselesionsheralda potentiallate blightepidemic,which,inamatterof days,couldwipeout theentire crop.
Immediateactionneedstobetaken:
eithercontact fungicidesneedtobe appliedor,ifthecropismature enough,itshouldbetop-killed.Inthe secondexample,abarleycropis infectedwithwhatappearstobenet blotch.Netblotchisoneofthose diseasesthatiseasilyconfused with othersimilar-lookingbutvery
Soilutionsispublishedthree times a yearbytheAgronomy
Centre,AlbertaAgriculture,Food andRuralDevelopment.Your comments oncurrent contents, ideasandcontributions for future articlesarewelcome.Forfurther informationphone,fax or writeto:
Soilutions
Alberta Agriculture,Food andRural Development
905,6909 -116Street, Edmonton,Alberta,T6H 4P2 c/o MarilynTouchette
Phone 427-6361, Fax427-1439
or
c/oJoanSeath
Phone 427-7098, Fax427-01 33
SoHutions
differentproblems, soitisespecially importanttobecarefulwith the diagnosis.Thereisafoliarfungicide thatcanbeapplied toeconomically controlnet blotchifthe barleycropis ofhighvalue,soit’simportantthatthe diagnosisiscorrect.Conversely,ifnet blotchisdiagnosedwhentheproblem
isactuallysomethingelse,an expensive but uselessapplication of fungicidecouldbe made.Evenifthe cropisn’tofhigh value(whichwould makefungicide applicationtoocostly), correctdiagnosisisstillimportant.
Actioncanbetakentoavoidfuture occurrencesofnetblotch,suchas turningunderallcropresidue, growingalternativecropsfor at least twoyears,andplantingonly treated seedofresistant varieties.
Oneproblemfacedbymanywould-be diagnosticiansisfindingthe
informationthatcantellthemwhat mightbecausing thesymptomsthey areseeinginthecrop.Thoughthere aremanysources,suchas
publications, thatdescribecrop
Karnal bunt in
T
heKarnalbuntproblemgrew worse,inMarch,whenit
turnedupindurumwheat growninArizona.The discoveryled tothe immediatesuspensionofallforeign wheat shipments bytheU.S.,the world’s biggestwheatexporter.As
infestationsturnedupinwheat growingdistrictsofTexas,New
Mexico andCalifornia,sometwo dozencountries,includingCanada, restrictedorbannedoutrightthe purchaseofU.S.wheatuntilthe outbreak couldbeeradicated.That mayproveatemporaryadvantagefor prairiewheatgrowers,whostandto pickup marketstheAmericanslose.
Butitcouldalsobecomea multimillion dollarheadacheforCanadianplant breeders.Muchofthe Canadianplant breeding industry countson multiplication plotsinthe U.S.
problemsin detail,theyaregenerally organizedbycause,so the
diagnosticianmustalreadyknowwhat heorsheislookingfor.Readingthis article,youwillhavenoticedthatmost oftheexamplesfocusonbarley.The
Soiland CropDiagnosticCentre and theAgronomyUnitareputting togetherafielddiagnosticmanualfor barley,whichcontainsinformation suchasisfoundin thisarticle,andis setupinsuchawaythat,inmost cases,anovicediagnosticianshouldbe able todeterminethecauseof a problem fromthe observable symptoms.Thismanualwillhelp Alberta barley producers,crop specialists,andothersworkingwith thecroptodiagnoseproblemsinthe field.Formoreinformation orto offer suggestions orcomments,please contact:
DeeAnnBenard SoilandCropDiagnostic Centre 6909-116St.Room905 EdmontonAB T6H4P2 Phone427-6361,FAX427-1439, E-mail[email protected].ab.ca
the U.S. leuanEvans,
PlantPathologist
southwest, the areanowunder quarantine, toproduce seedinthe winterforplantinghereinthespring.
Allspringwheats,rye,triticale,oats andevenbarleygrowninthatarea cannotbe importedintoCanadafor springplanting this year.
Karnalbunt,namedafteratownin India,isa fungaldiseasethatattacks wheat andtriticale.It isprimarily confinedtoMexico andAsia.Karnal bunt turns the kernelsofinfected grain into apowderysootthatsmells likerottingfish.A1-2%buntinfection willresult in rejection ofwheatfor foodpurposes. Karnal buntisdifficult to eradicate;itssporescanlay dormantin fieldsforupto5years,and then spreadonthewindorbecarried tootherfieldsby farmequipment.
Therearenofullyeffectivechemical methodsofcontrollingKarnalbunt.
Solutions
Fertilizing Spring Wheat for Yield and Protein
RossH.McKenzieand AllanMiddleton AgronomyUnit,Lethbridge
A
commonquestionwewere askedover the winterwas“Is
iteconomicaltofertilize springwheatwithadditional nitrogento obtaina protein premium?”Toanswerthisquestion, let’sbeginbyreviewing thefactors thataffectproteininspring wheat.
Theyinclude:
• soilnitrogenlevelsatthetimeof seeding
• theamountofnitrogenfertilizer applied prior toseeding orin-crop application
• soilmoistureatthetimeofseeding
• timeandamountofprecipitation during thegrowingseason,and
• temperatureandheat(degree days) during thegrowingseason.
Environmentalconditionsduring the growingseasonplay avery important role ininfluencingspringwheat proteincontent.Ifwe knewwhatthe weatherwould belikeduring the growingseasonof1996,itwould be possible togiveareasonably accurate answer.
Withthisinmind,letslookatafew scenariostoseehowproteincontent variesunderenvironmentallydifferent conditions:
• WhenavailablesoilNlevelsarelow andthereisnomoisturestress,N
ratesupto90lb/acwillbeused almostentirely toincreaseyield.At
Nratesgreaterthan90lb/ac increasesinproteinmayoccur.
• Underintermediatemoisturestress and lowtomoderatesoilavailableN
levels,theaddition ofnitrogen fertilizer willincreasebothyieldand proteinatthesametime.
• Underprolonged moisturestress withmoderatesoilnitrogenlevels, particularly laterinthegrowing
season,theaddition ofnitrogen fertilizerwillmainlyaffectprotein content buthavelimitedifany influenceongrainyield.
LetsnowlookatTable1(below) whichhas theyieldincreaseforspring wheatintheDarkBrownsoilzone, assumingthatthereis;30lb/acofNin thesoil,4inchesofsoilmoistureat thetimeofseedingand,7 inchesof precipitationduring thegrowing season.Itisalsoassumedthenitrogen fertilizer isapplied prior to oratthe timeofseeding.Table1hastwoprices fornitrogenfertilizer,350 and450/lb andassumesaspringwheatprice of
$4/bu.Theeconomicanalysissuggests thatat350/lb forN,that40lbofN/ac
iseconomical,ata 2:1return,froma grain yield standpoint.IfNwas450/lb, theanalysissuggeststhat30lbofN/ac
iseconomical,ata 2:1 return.
Tolookfurtheratthefirstscenario,at 350/lbforNfertilizer,itiseconomical toadd40lb/acofNfertilizer ata cost of$14peracre.Fromourfield researchwethinkthiswouldgive approximatelya50to60%chanceof havingaproteincontentatabout 13.5% andwould produceabout37 bu/actotalandat$4/buthiswouldgive agross returnof$148/ac.
However,ifweassumethatthe premiumfor14.5%proteinwheatwill
beanadditional750/buandifan additional20lb/acofNwereadded, thiscould increase theprobability to
75%ofhavingwheatat14.5%.The
additionalcostofthefertilizerwould be $7per acreandthiswould produce about 39.5 bu/acatavalueof$4.75/bu togiveagross returnof$188/ac.
Therefore spendinganextra $7/ac onnitrogen couldreturnan additional $40/ac.
cont’donpage 4
Table1.DeterminationofeconomicnitrogenfertilizerresponseofspringwheatintheDark Brownsoilzone assumingstoredsoilmoistureis4inches+pptnis7inches,whensoiltest nitrogenis30lb/ac(0-24 inch depth).Twonitrogenfertilizercostsof350 an450/lb are used.
Fertilizeraddedisinlb/acandyieldsareinbu/ac.Theboldnumbersindicatethepointwhere marginaleconomicreturnis2:1
.
NFertilizerAdded 0 10 20 30 40 50 60 70 80 90 100
ExpectedYield AddedYieldIncrease/
25.4 29.6 32.7 35 36.8 38.3 39.5 40.5 40.5 40.5 40.5
10lb/acN 4.2 3.1 2.3 1.8 1.5 1.2 1 0 0 0
1.FertilizerCost 3.50 3.50 3.50 3.50 3.50 3.50 3.50 3.50 3.50 3.50
$0.35/lbWheat
@$4.00/bu 16.80 12.40 9.20 7.20 6.00 4.80 4.00 0 0 0
2.1
2.FertilizerCost 4.50 4.50 4.50 4.50 4.50 4.50 4.50 4.50 4.50 4.50
$0.45/lbWheat
@$4.00/bu 16.80 12.40 9.20 7.20 6.00 4.80 4.00 0 0 0
2.1
FertilizingSpringWheat
(cont’d)
When welookatthesecondscenario of 450/lb forNfertilizer,itis economicaltoadd30lb/acofN
fertilizeratacostof$13.50 peracre.
Thiswouldgiveabouta50%chanceof havingaproteincontentatabout 13.5% and would produceabout35 bu/ac,at$4/bu, for agross returnof
$140/ac.Ifanadditional30lb/acofN
wereaddedatanadditionalcost of
$13.50 peracre, thiscould increase theprobability to75%ofhaving high proteinwheatat14.5%.This should produceabout 39.5 bu/actotal at
$4.75/bu, foragross returnof$188/ac.
Therefore,spendinganextra
$18/aconNfertilizercould return anadditional $48/ac.
Thesetwoscenariosmakeitlook promisingtofertilizeforprotein rather thanyield.Remember,theprobability forreaching high proteinisaffected greatlyby weatherconditions.
Further,thepremiumpaid forNo.1 springwheatat14.5%proteinwas about800/buinthelastcropyear.If
thepremiumisonly200/buinthenext cropyear, thatwoulddramatically affecttheeconomicpicture.
Therefore,fertilizingforhigh proteinwheatisagamble and can be veryrisky.Ifyoudecideto tryit this year,doitonasmallscale,to keep yourrisk to aminimum!!
!
Soiliftfoffls
Comparing Apples and Oranges
MorePromulgations froma Plant Pathologist
I.R.Evans, PlantPathologist
henwheat,barley, oats, canolaandother crops varietiesaretestedin Alberta,they are assessedon
performancerelated to region,daysto maturityandsuitabilityforproduction underirrigation.
Thereislittlecorrelation of performancewithsuchfactors assoil
pHormicronutrientavailability.We now knowthatcerealssuchas oats, wheat andbarley are strongly influencedbysoilpH.InAlbertawe’ve got rangesfrombelow5towellover 8.Someoat cultivarswillperformbest atlowerpH’s, othersatpH’sclose to neutral.Itstandstoreasonthatifan oat varietywasselectedonhighpH
soilsitwould performoptimallyinthe
pHrangeforwhichitwasselected.
Theconversewould betrueforoat cultivarsselectedforlowpHsoilsasis
theusualcustominEuropewhere
oatsareregardedasthemosttolerant of acidsoilconditions.
CopperresearchinAlbertaindicates thatthere are considerabledifferences betweenbarleyandoat varietal responsestosoilcopperavailability.
Somebarleyandoats varietiesare relativelyyieldsensitivewhile others areveryyieldtolerant tolowsoil availabilitycopperlevels.
Isitpossible thatatsomeofourtrial siteswe maybe measuringthecopper responseofthesecultivars.In effect theirresponsetocoppermaybethe mostimportantfactorindetermining actualyield differences.
Itwouldthenbeprudentthatwhen assessingvarietiesofanycropfor yieldperformanceweshouldensure thatthemacro andmicronutrient contentsandpHofthesoils,ateach and everytestsiteareatoptimumor nonlimiting levels.
Aninterestingobservationwas madea fewyearsagowhenanaccidental doubledoseofAvadex wasapplied to wheattrialplotsinvolvingeight varieties.Thosewheatvarieties developedbeforeAvadex wasonthe marketwereseverelysetback bythe double dose.Those“newer” wheats likelyselectedbyplantbreeders, usingAvadexforweedcontrol,were verytolerant ofthe doubledose.
Avadexusedas aweedcontrol chemicalinawheatvarietytrialcould influence yieldcomparisonsbetween these “older”and“newer”wheats.
Solutions
Optimizing Barley Silage Production in Alberta
RossMcKenzie,AgronomyUnit,Lethbridge ElstonSolberg,AgronomyUnit,Edmonton pproximately 750,000to
800,000 acresofbarleysilage areproducedannuallyin Alberta.Limited research has been conductedtodetermine whichbarleyvarietieshavethebest yield potential,agronomic
characteristicsandfeedquality for silageproductioninthe varioussoil
andclimaticareasofAlberta.The
interactive effects offertilizerand precipitationfurthercomplicate the problemforfarmers attemptingto selectthe best barleyvarietiesand optimumfertilizerrequirementsfor silageproduction.
Aresearchprojectfunded bythe AlbertaBarleyCommissionandthe Alberta AgricultureResearchInstitute
wasstarted in1994todetermine whichbarleyvarietieshavethe best yieldpotentialandagronomic characteristics for silageproduction.
Thesecondobjectiveistodetermine theoptimumeconomicfertilizer
recommendationsforbarleysilage productionunderirrigationin southern Albertaanddryland conditionsintheDark Brown, Thin Black,BlackandGrayWoodedsoil areasof Alberta.
Thefivebarleyvarieties(Table1) selectedforstudy includedLeduc, Tukwa,Seebe,ACLacombeandCDC
Earl.Asixth variety,Duke was includedintheirrigatedtrials.
Eachbarleyvarietyhadpre-plant bandedNtreatmentsat0,40, 80,120, Table 1.Agronomiccharacteristics ofbarley
160 and 200 kgNha'1.Ablanket application ofseed- placedphosphate (P2O5)ata rate of30 kgha'1was
appliedwithallNtreatments.
Treatmentsof P,KandSwerealso included. All varietieswereseededto achieveaplantpopulationof250 plantsm" .
Onlytheeffectsofnitrogenonyield andprotein arediscussedhere.
Effectsof NitrogenFertilizeron Yield
Nitrogenfertilizerresponsewas dramaticatnineofthe 11 research siteswithyieldincreasesupto400%
overcontroltreatments.
Fortheirrigated sitesatBowIsland, LethbridgeandCoaldale,ACLacombe (Table2)was amongthehighest yielding varieties.Seebe andTukwa werealsohighyieldingatBowIsland andLethbridge.Lodgingoccurredat allthreeirrigatedsites,with theworse lodging occurringatBowIsland.
At Barons and HighRiver (Table2), allvarietiesperformedwellexcept
CDCEarl.AtPincher Creek, the three highestyielding varietieswere Seebe,TukwaandACLacombe. At Strathmore,Leducwassignificantly higheryieldingthan the other varietieswhichwerenotsignificantly differentfromeachother.
At Lacombe,Leduc,TukwaandAC Lacombe werethehighestyielding varieties.AtMillet,Ellerslieand
varietiesusedintheproject.
Barrhead,Seebewasconsistentlythe highestyielding variety. In1995,
TukwaandACLacombealso did reasonably wellatthese threecentral Albertasites.
Therewassignificantlodgingat
BarrheadandLacombesites.
Considering theresults ofallthe centralAlbertasites,Seebe,AC LacombeandTukwawerefrequently thehigheryielding silage varieties.
ProteinContentofDryMatter Atthethreeirrigatedsites,Bow
Island,CoaldaleandLethbridge,CDC
Earl consistentlyhadthehighest proteinlevels(Table4).Dukealso tendedtohaverelativelyhigh protein levels.
AtBarons,Strathmore and High River,CDCEarlhadthehighest proteinlevels,followedbySeebe and Tukwa. At mostofthesouthernsites,
Leduc hadthelowest proteinlevels.
Thissametrendwasalsoobservedat thecentralAlbertasites(Table5).
Closerexaminationofthe proteindata
showsthatwhensoilNlevelswere
low,theaddition ofonly40kgNha’1 resultedinincreaseddrymatteryield butcauseda slight tovery dramatic decline inproteinlevels.Whenasmall amountofNisadded, increased vegetativegrowthoccurs,however theplants lack sufficientNforthe entiregrowingperiod,resulting in lowerproteinlevels.
Summary
Thefirstand secondyearresults of thisstudyshowthere aresignificant differencesamongbarleyvarietiesin dry mattersilageproduction.Nitrogen and phosphatefertilizercan
dramaticallyincreasesilageyield potentialwhensoiltest levels ofthese nutrientsarelow.
cont’don page6
Variety Row Awn
Type
Lodging Resistance
Scald N
B
q l>1(
ir q - i . 1
AC Lacombe 6 Smooth Verygood Intermediate Intermediate Susceptible
Leduc 6 Rough Fair Resistant Intermediate Intermediate
Seebe 2 Rough Good Resistant Susceptible Intermediate
CDCEarl* 6 Rough Excellent Resistant Intermediate Intermediate
Tukwa* 6 Smooth Verygood Intermediate Intermediate Intermediate Duke 6 Rough Excellent Intermediate Susceptible Intermediate
*semi-dwarf
Sol\utions
Thereisoften aprofoundinteraction effectbetweennitrogenandvarietyon silageproteinlevel.
Thisworkwillcontinuein1996.At the completionofthefieldstudy,we
willseewhichbarleyvarietieshave
the bestsilageandproteinyields underdifferentenvironmentaland managementconditions.Nutrient responsecurveswillbedevelopedfor makingeconomicalfertilizer
recommendations andperhapsto predictproteinyield potential.
Theauthorsgratefullyacknowledge fundingfor thisprojectfromthe AlbertaBarleyCommissionandthe AlbertaAgriculturalResearch Institute.
RossMcKenzie -SouthandSouth Central Elston Solberg-Central
Table2. Meanbarleysilage yield(kg/ha)ofallfertilizertreatmentsatthesouthern Albertasitesin1995.
ACLacombe 17230a 14559ab 17116a 10188a 7896ab 12949a 12243b
CPCEarl 15871c 14496ab 14986be 9652b 7510be 11634b 11848b
Leduc 17018ab 13296c 15512b 10303a 7325c 12933a 12843a
Duke 16446be 13777be 14639cd - - -
*YieldsfollowedbythesameletterarenotsignificantlydifferentusingDuncan’sMultipleRangeTest.
Table 3.Meanbarleysilage yield(kg/ha)ofallfertilizertreatmentsatthecentralAlbertasites.
ACLacombe 1 1642ab 9620b 6120b 8048b
CPCEarl 9682c 8151c 5372c 7965b
Leduc 12362a 9543b 5957b 7788b
*YieldsfollowedbythesameletterarenotsignificantlydifferentusingDuncan’sMultipleRangeTest.
Table 4.Meanbarleysilage protein level(%)ofallfertilizertreatmentsatthe southern Albertasitesin1995.
ACLacombe 9.48d 9.38c 13.87c 7.27c 11.28d 9.86c 11.44c
CPCEarl 10.85a 11.49a 15.80 ab 8.75a 12.29b 11.36a 13.08a
Leduc 8.67e 9.22c 12.97d 7.01c 11.73 cd 9.29d 10.48d
Duke 10.66 ab 11.39a 15.21 b - - - -
*YieldsfollowedbythesameletterarenotsignificantlydifferentusingDuncan’sMultipleRangeTest.
Table 5.Meanbarleysilage protein levels(%)ofallfertilizertreatmentsatthecentralAlbertasitesin1995.
CPCEarl 13.66a 12.99b 9.56a 13.65a
Leduc 10.59d 10.89 de 8.72b 10.55d
*Yields followedbythesameletterarenotsignificantlydifferentusingDuncan’sMultipleRangeTest.
