montana ag alert - montana state university

MontanaAgAlertCroplandDisease6July,2017

Commonpulsecropdisorders:nutrient,droughtanddisease

TheSchutterDiagnosticLaboratory(andMaryandJessica’scellphones)haveseenalotofchickpeas,peas,andlentilslookingabitpeakedthesedays.Here’sarundownofthecommonthings:

1.Yellowchickpeas.Inthebeginning,theseplantswerescatteredandweputthecauseuptodamagedseed/’chickpeasjustdothat.’Now,wholefieldsareaffected,probablyexacerbatedbythehotdryconditions.Inmanycases,thelowerpartoftheplantisyellowwhiletheupperleavesaregreen.Itisverydifficulttodigpulsecroprootsoutofcement,somanyoftherootswehaveseenarestrippedandhaveveryfewnodules.Somehaverootrot,particularlyRhizoctoniarootrot.Wearespeculatingthatnodulationmayhavebeenpoorinthespring,andwiththehotdryconditionstheplantsareharvestingnitrogenfromtheolderleaves,causingthemtoturnyellowanddropoff.Picsbelow.Rootrotwouldexacerbatethisbynotallowingwatertoflowintotheleavesaswellashealthyroots.

Yellowedchickpeas.

Lowerleavesareyellow,rootshaveveryfewnodulesandsomehaverootrot.Upperleavesaregreen.Symptomscannotbetiedtoherbicidehistory.

PreviousresearchbyPerryMillerindicatedthat‘rescue’treatmentsofnitrogen8weeksafterplantinghadnobeneficialeffectonyieldofnon-inoculatedpulses,andnitrogenappliedinJulyisunlikelytomakeitintotherootzonebecauseofgenerallylowprecipitationamounts.2.Rootrotsonallpulses:Wearestartingtoseealotofpatchesofdecliningpulsecrops.Foliagemayinitiallybeyellow,androotsarebrownorblack.Theinitialcausemayhavebeenanotherfungus,butweareprimarilyrecoveringRhizoctoniarootrotatthispointintheseason.Norecoverytreatmentsareavailable.Usegoodcroprotationpracticesandaseedtreatmentintheupcomingyears.

3.Ascochytablightonchickpea:Wheretherearegoodcropswithacanopyandmorningdews,we’reseeingalotofascochytablightpopuponchickpea.Nothingonlentilandonlyscatteredreportsonpea.Fungicidesmaybeanoptioninchickpea,seetheearlieralertforrecommendations.Thediseaseshutsdownabove25-30C(77-86F),andpodfillalsodeclineswhenwehave90Fdays,soIwoulddelayanyfungicidedecisionuntilafterthelatestheatwaveifthereisnoevidenceofdisease.Ascochytamayresurgelaterintheseasonbutpayattentiontopreharvestintervalsonalllabels.

Ascochytablightsymptomsonchickpea

4.Bacterialblightonallpulses:Bacterialblightfollowshail.Distinctlesionsstopattheveins.SeethePulsecropdiseaseguideforphotosathttp://msuextension.org/pspp/documents/DiseasesofCoolSeasonLegumes.pdf

Thereisnotreatmentforthisdisease,usecleanseedlotsinfutureyears,particularlyifthediseaseaffectsthepods.

Asalways,contactusifyouhaveanyquestionsorconcerns.--MaryBurrows,599-9966,mburrows@montana.edu--JessicaRupp,994-5572,jessica.rupp@montana.edu--ClainJones,994-5067,clainj@montana.edu