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 – 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 ++ +++ ++ +++ 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 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) (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

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? CornCorn –– varietiesvarieties susceptiblesusceptible toto IIIB,IIIB, lessless IVIV –– NoNo aboveabove--groundground symptomssymptoms –– NoNo effectseffects onon yieldyield –– LesionsLesions onon rootsroots –– BuildBuild--upup dependsdepends onon favorablefavorable weatherweather forfor infectioninfection –– NumerousNumerous fieldfield trialstrials Non-inoculated control following corn R. solani AG 2-2 IV following corn R. solani AG 2-2 IIIB following corn WhatWhat aboutabout susceptiblitysusceptiblity ofof soybeansoybean (beans)(beans) toto R.R. solanisolani AGAG 22--22 ISGs?ISGs?

Soybean/BeanSoybean/Bean cropscrops –– SymptomsSymptoms may/maymay/may notnot bebe observedobserved –– IncreaseIncrease populations,populations, esp.esp. ofof IIIBIIIB Varieties/germplasmVarieties/germplasm notnot screenedscreened –– MayMay bebe somesome differencesdifferences amongamong currentcurrent varietiesvarieties BuildBuild--upup onon sugarbeetsugarbeet alsoalso affectaffect soybeansoybean Sugarbeet 2007, Soybean 2008 Sugarbeet 2007, Soybean 2008 Sugarbeet 2007, Soybean 2008 Sugarbeet 2007, Soybean 2008 RhizoctoniaRhizoctonia controlcontrol strategiesstrategies

LengthenLengthen rotationrotation betweenbetween beetbeet cropscrops – R. solani increasing over time Rhizoctonia control strategies

Avoid cultivation/rotary hoe unless necessary for weed control Keep soil out of crowns during cultivation

Trends in cultivation practices

Sugarbeet Variety 2008 Season Conventional Roundup Ready

% Growers who 95 32 cultivated

Average number 1.4 0.4 of cultivations

From: J. Stachler. 2009. Sugarbeet Research and Extension Reports RhizoctoniaRhizoctonia controlcontrol strategiesstrategies

Lime??Lime?? WeedsWeeds needneed toto bebe controlledcontrolled everyevery yearyear –– WeedsWeeds areare susceptiblesusceptible toto infectioninfection –– Examples:Examples: pigweed,pigweed, lambsquarterslambsquarters