ManagingManaging RhizoctoniaRhizoctonia CarolCarol WindelsWindels && JasonJason BrantnerBrantner UniversityUniversity ofof MinnesotaMinnesota NWNW ResearchResearch && OutreachOutreach CenterCenter CrookstonCrookston WhyWhy isis RhizoctoniaRhizoctonia increasing?increasing? FavorableFavorable weatherweather PlantingPlanting ofof susceptiblesusceptible cropscrops inin rotationsrotations -- CropsCrops affectaffect populationspopulations ofof R.R. solanisolani inin soilsoil HowHow toto managemanage RhizoctoniaRhizoctonia onon sugarbeetsugarbeet -- PlantPlant resistanceresistance -- FungicidesFungicides -- CulturalCultural practicespractices BackgroundBackground:: RhizoctoniaRhizoctonia solanisolani Common soil fungus – worldwide Infects wide range of plants – Field crops, weeds, vegetables, ornamentals – Temperature: 55-95 0F; ideal = 70 - 85 0F – Soil moisture: variable; ideal = wet DiseaseDisease atat SelectedSelected TemperaturesTemperatures Inoculated, no fungicide 80°F 70°F 60°F 50°F Source: Dr. Melvin Bolton & M. Khan BackgroundBackground:: RhizoctoniaRhizoctonia solanisolani Common soil fungus – worldwide Infects wide range of plants – Field crops, weeds, vegetables, ornamentals – Temperature: 55-95 0F; ideal = 70- 85 0F – Soil moisture: variable; ideal = wet Survives – Infected (diseased) plants – Colonizes plant debris?? – Occurs in 0 to 6 inch depth R.R. solanisolani –– aa complexcomplex speciesspecies ComposedComposed ofof differentdifferent populationspopulations –– AnastomosisAnastomosis GroupsGroups == AGAG R.R. solanisolani AGAG 22--2:2: crowncrown && rootroot rotrot (RCRR)(RCRR) –– AGAG--22--22 IVIV && AGAG 22--22 IIIBIIIB (intraspecific(intraspecific groups)groups) RhizoctoniaRhizoctonia solanisolani AGAG 22--22 ISGsISGs knownknown toto attackattack cropscrops growngrown inin MNMN && NDND R. solani R. solani Crop AG 2-2 IV AG 2-2 IIIB Sugarbeet ++ +++ Soybean ++ +++ Edible beans ++ +++ Corn - + Wheat - - - = nonhost ++ = moderately aggressive + = slightly aggressive +++ = severely aggressive CompareCompare 19951995 toto 20072007 acresacres FROM: USDA Agricultural Statistics Service WhatWhat ISGsISGs ofof R.R. solanisolani AGAG 22--22 occuroccur inin thethe RRVRRV && SouthernSouthern Minnesota?Minnesota? ~965~965 isolatesisolates fromfrom 309309 fieldsfields (2005(2005--2008)2008) –– FromFrom sugarbeetsugarbeet withwith rootroot && crowncrown rotrot –– RRV:RRV: 460460 isolatesisolates (155(155 fields)fields) –– So.So. MN:MN: 504504 isolatesisolates (154(154 fields)fields) IdentifyIdentify toto ISGISG byby temperaturetemperature--growthgrowth –– AGAG 22--22 IIIBIIIB growsgrows atat 9595 0FF –– AGAG 22--22 IVIV doesdoes notnot growgrow atat 9595 0FF ConfirmConfirm byby molecularmolecular teststests What is the prevalence of R. solani AG 2-2 ISGs? ~ 964 isolates of R. solani AG 2-2 collected from infected sugarbeet: Red River Valley (460) So. Minnesota (504) Traditional small grain rotation Sugar beet rotated with Shift to corn/soybean last 10 yr corn/soybean since 1975 7% AG 2-2 IV 21% 23% AG 2-2 IIIB Intermediate 27% 66% 56% Prevalence of ISG in the RRV by previous crop 6% 17% 77% Wheat (230) AG 2-2 IV AG 2-2 IIIB Corn? (6) 14% Intermediate 13% 6% 29% 57% 81% Soybean (48) Potato (16) Distribution of R. solani AG 2-2 ISGs in ND and MN R. solani AG 2-2 IV present R. solani AG 2-2 IIIB present Both ISGs present ReasonsReasons forfor variablevariable RhizoctoniaRhizoctonia diseasedisease RhizoctoniaRhizoctonia controlcontrol strategiesstrategies CorrectCorrect diagnosisdiagnosis ofof rootroot rotrot problemproblem –– SymptomsSymptoms –– ContactContact agriculturistagriculturist –– MayMay requirerequire lablab analysisanalysis Rhizoctonia FROM: Suagrbeet Advancement: On Farm Research and Demonstration NonNon--typicaltypical RhizoctoniaRhizoctonia AphanomycesAphanomyces RhizoctoniaRhizoctonia controlcontrol strategiesstrategies CorrectCorrect diagnosisdiagnosis ofof rootroot rotrot problemproblem –– SymptomsSymptoms –– FieldField historyhistory –– AssessmentAssessment ofof diseasedisease severityseverity AssessmentAssessment ofof severityseverity ofof RCRRRCRR Severity of Description No.plants/ % RCRR (aboveground symptoms) 1,000 ft row Diseased* Scattered plants here and there, Light < 25 1.4% occasional small patch Easily seen when walking, Moderate 25 – 170 1.4 - 9.7% patches randomly found Plants or patches found every Severe > 170 >9.7% few steps *Assume 175 plants /100 ft row From: Mr. Steve Poindexter, Michigan State University Extension Michigan has a high tolerance for “pain” with this disease RhizoctoniaRhizoctonia controlcontrol strategiesstrategies PlantPlant varietiesvarieties withwith partialpartial resistanceresistance –– YieldYield andand profitabilityprofitability –– SlowSlow downdown buildupbuildup ofof pathogenpathogen inin soilsoil PlantPlant earlyearly –– SoilSoil isis << 6060--7070 0F,F, avoid/minimizeavoid/minimize infectionsinfections 20092009 RhizoctoniaRhizoctonia –– specialtyspecialty varietiesvarieties (A(A––C)C) Variety RCRR* Roundup Ready Crystal 770 RR (+ Aph) 2.0 Conventional Hilleshog 3035 Rz (+ Aph) 1.9 SESV H46714 2.4 Beta 1301 R (+ Aph) 2.6 Hilleshog 3052 Rz (+ Aph) 3.3 *Moorhead, MN & Ft, Collins, CO (2007&2008) 0-7 scale, 0=healthy, 7=severely rotted Rhizoctonia control with fungicides Band rate / Total Estimated Label Fungicide fl oz/1000 ft* oz pct/A Cost/A** Timing In-furrow to Quadris 0.4 – 0.6 9.5-14.3 $29 - $43 row closure 4-leaf to Proline 0.24 5.7 $22 row closure Headline 0.4 – 0.8 12.0 $28 In-furrow *7-inch band, 22-inch rows **Based on local source DiseaseDisease SeveritySeverity ++ VarietyVariety ++ FungicideFungicide Severity of Fungicide Rhizoctonia Variety type 7-inch band* Light Moderately resistant No Susceptible 2/3 full rate * A wider band reduces effective rate A narrower band allows use of lower rate From: Mr. Steve Poindexter, Michigan State University Extension DiseaseDisease SeveritySeverity ++ VarietyVariety ++ FungicideFungicide Severity of Fungicide Rhizoctonia Variety type 7-inch band* Light Moderately resistant No Susceptible 2/3 full rate Moderate Moderately resistant 2/3 full rate Most resistant No * A wider band reduces effective rate A narrower band allows use of lower rate From: Mr. Steve Poindexter, Michigan State University Extension DiseaseDisease SeveritySeverity ++ VarietyVariety ++ FungicideFungicide Severity of Fungicide Rhizoctonia Variety type 7-inch band* Light Moderately resistant No Susceptible 2/3 full rate Moderate Moderately resistant 2/3 full rate Most resistant No Severe Most resistant Full rate (1X-2X) * A wider band reduces effective rate A narrower band allows use of lower rate From: Mr. Steve Poindexter, Michigan State University Extension Medium Rhiz* Treatment RSA $/A Quadris + Proline (both at 4 lf) - - Quadris (4-6 lf) 8456 1069 Proline (4-6 lf) 8139 999 Check 7919 970 *FROM: Chad Wardner. 2008. American Crystal Sugar Co. **FROM: Dave Bailey. 2008. Sugarbeet Advancement: On Farm Research and Demonstration. Sugar Beet Growers, Michigan Sugar Company, Michigan State University, Agribusiness Medium Rhiz* Heavy Rhiz** Treatment RSA $/A RSA $/A Quadris + Proline (4 lf) - - 6585 a 952 Quadris (4-6 lf) 8456 1069 6277 ab 922 Proline (4-6 lf) 8139 999 5754 ab 841 Check 7919 970 4802 b 730 *FROM: Chad Wardner. 2008. American Crystal Sugar Co. **FROM: Dave Bailey. 2008. Sugarbeet Advancement: On Farm Research and Demonstration. Sugar Beet Growers, Michigan Sugar Company, Michigan State University, Agribusiness 70°F, Quadris trial Treated Non-treated Control Source: Dr. Melvin Bolton & M. Khan 70°F, Proline trial Treated Non-treated Control Source: Dr. Melvin Bolton & M. Khan Fungicides:Fungicides: TimingTiming && PlacementPlacement Apply at or near time of infection – Controversy over importance of soil temperature In field with moderate disease pressure – 8-10 leaf stage (before last cultivation) In fields with high Rhizoctonia disease pressure – Avoid planting (or in-furrow + 4-6 leaf) – 4-6 leaf stage + 8-10 leaf stage Too early or too late = inadequate protection Band applications more effective than broadcast Effective when infection starts at crown - but not when infection starts in soil NoteNote Quadris phytotoxic to sugarbeet when: – Any herbicide with an oil adjuvant – Microrate herbicides (+ 7 days) – Starter fertilizer: 10-34-0 in-furrow Quadris + other pesticides Proline Label – test compatibility, phytotoxicity RhizoctoniaRhizoctonia controlcontrol strategiesstrategies RotateRotate cropscrops toto minimizeminimize buildbuild--upup –– WheatWheat (barley)(barley) –– bestbest rotationrotation beforebefore sugarbeetsugarbeet –– SoybeanSoybean--edibleedible beanbean -- avoidavoid beforebefore sugarbeetsugarbeet ,, esp.esp. ifif IIIBIIIB inin fieldfield –– CornCorn –– avoidavoid beforebefore sugarbeet,sugarbeet, esp.esp. ifif IIIBIIIB inin fieldfield Soil inoculated R. solani AG 2-2 IV, IIIB & control Planted to rotation crops followed by sugarbeets Wheat Soybean Corn Not inoculated Wheat Corn Soybean R. solani AG 2-2 IV Soybean Corn Wheat R. solani AG 2-2 IIIB WhatWhat aboutabout susceptiblitysusceptiblity ofof wheatwheat toto R.R. solanisolani AGAG 22--22 ISGs?ISGs? WheatWheat –– GoodGood rotationrotation cropcrop forfor reducingreducing RCRRRCRR –– Historically,Historically, RSARSA ofof sugarbeetsugarbeet followingfollowing wheatwheat (barley)(barley) veryvery goodgood onon aa widewide rangerange ofof soilsoil typestypes WhatWhat aboutabout susceptibilitysusceptibility ofof corncorn toto R.R. solanisolani AGAG 22--22 ISGs?ISGs?