Management of Rhizoctonia in Sugarbeet

achanda@umn.edu Office: 218-281-8625 @BeetPath Management of Rhizoctonia in Sugarbeet 2019 SMBSC Production Seminar, Willmar, MN Ashok K. Chanda Assistant professor/ Extension Sugarbeet Pathologist Northwest Research and Outreach Center, Crookston Dept. of Plant Pathology, University of Minnesota

Summary of Field Samples 2016-2018 70 63 60 50 44 45 2016 2017 2018 No. of Fields 40 30 20 36 23 19 10 0 9 3 2 3 2 1 2 2 Rhizoctonia Aphanomyces Rhizoctonia + Aphanomyces Cause of Problem Fusarium 7 Chemical

Rhizoctonia + Aphanomyces July 21, 2015

Damping-off

Crown and Root Rot

Rhizoctonia affects Yield Yield T/A 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 Resistant and Moderately Susceptible Varieties r = -0.88 y = -3.2117x + 34.468 R² = 0.7703 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Rhizoctonia Root Rot Rating

Rhizoctonia Fungus Rhizoctonia solani 13 Anastomosis groups Sugarbeet- Anastomosis groups AG 2-2 (seedling and adult) and AG 4 (seedling) AG 2-2 has intraspecific groups (ISGs) AG 2-2 IIIB and AG 2-2 IV Both ISGs cause same symptoms on sugarbeet Both occur in MN/ND (Windels, 2009)

AG 2-2 IV vs AG 2-2 IIIB RRV (460 cultures): AG 2-2 IV most common (66%) So. MN (504 cultures): AG 2-2 IIIB most common (56%) (Windels, 2010)

Management of Rhizoctonia Early planting

Management of Rhizoctonia Early planting Crop Rotation Length of rotation Weed control Crop choice

Soybeans

Soybeans No emergence with Rhizoctonia in the furrow

Navy beans

Management of Rhizoctonia Early planting Crop Rotation Crop choice Length of rotation Weed control Resistant varieties

Rhizoctonia rating scale Reynolds et al.

Rhizoctonia & Resistant Variety (~3.4) No. plants/100 ft. of row 220 200 180 160 140 120 100 80 60 40 20 0 0 20 40 60 4"ST 60 F 220 200 180 160 140 120 100 80 60 40 Soil temp. ( F) Date

Rhizoctonia & Moderately Resistant Variety (~4.0) No. plants/100 ft. of row 220 200 180 160 140 120 100 80 60 40 20 0 0 20 40 60 4"ST 60 F 220 200 180 160 140 120 100 80 60 40 20 0 Soil temp. ( F) 5/26 6/2 6/9 6/16 6/23 6/30 7/7 7/14 Date 7/21 7/28 8/4 8/11 8/18

Rhizoctonia & Susceptible Variety (~5.3) No. plants/100 ft. of row 220 200 180 160 140 120 100 80 60 40 20 0 0 20 40 60 4"ST 60 F 220 200 180 160 140 120 100 80 60 40 20 0 Soil temp. ( F) Date

Management of Rhizoctonia Early planting Crop Rotation Crop choice Length of rotation Weed control Resistant varieties At-planting fungicides Seed treatment

Seed treatments SDHI class of fungicides Single site of action (Succinate DeHydrogenase Inhibitor) Inhibit fungal respiration

Seed treatments Kabina 14 g (Penthiopyrad, 2014) Vibrance 1.5 g (Sedaxane, 2016) Systiva 5 g (Fluxapyroxad, 2017) Metlock Suite [Metconazole + Rizolex) + Kabina 7g (Penthiopyrad), 2014) From 2017, 100% seed is treated for Rhizoctonia and treatment depends on the seed companies choice

Seed treatments - 2015 250 No. plants per 100 ft of row 200 150 100 50 Non-inoculated Systiva + 15 g Stamina Met. Suite + 7 g Kabina 14 g Kabina ST 2 g Vibrance 0 0 7 14 21 28 35 42 49 56 63 70 Days after planting Untreated control

Seed treatments 2016 250 No. plants per 100 ft of row 200 150 100 50 Kabina 14 g Metlock Suite + Kabina 7 g Systiva 5 g Vibrance 1.5 g Untreated control 0 0 7 14 21 28 35 42 49 Days after planting

Seed treatments 2017 300 No. plants/100 ft of row 250 200 150 100 50 0 Untreated Kabina Metlock Suite + Kabina Systiva Vibrance 0 7 14 21 28 35 42 49 56 63 Days after planting

Benefits of seed treatments Sugarbeet seedlings are very susceptible to Rhizoctonia early on Genetic resistance is not expressed until 6-8 leaf stage Effective protection of seedling (4-5 weeks) Ease of use -It comes with seed Safety No plugged nozzles

Management of Rhizoctonia Early planting Crop Rotation Crop choice Length of rotation Weed control Resistant varieties At-planting fungicides Seed treatment In-furrow application

In-furrow treatments 2016 250 No. plants per 100 ft of row 200 150 100 50 Quadris I-F 10 fl oz Satori I-F 10 fl oz Xanthion I-F 9 + 1.8 fl oz Headline I-F 9 fl oz Untreated control 0 0 7 14 21 28 35 42 49 Days after planting

In-furrow treatments 2018 No. plants/100 ft of row 200 150 100 50 0 0 7 14 21 28 35 42 49 56 Days after planting Xanthion I-F 9 + 1.8 fl oz/a AZteroid I-F 11.9 fl oz/a Untreated control Quadris I-F 9.5 fl oz/a

Benefits In-furrow treatments Sanitizing the furrow (seedling + soil) More effective than seed treatments longevity up to 8-10 weeks (Windels, 2010) Risks Phytotoxicity cool weather and light soils Mixing with starter fertilizer and other chemicals Plugged nozzles

Azoxystrobin + 10-34-0 Just after mixing Quadris Satori Equation 10-34-0 Starter

Azoxystrobin + 10-34-0 10 minutes after mixing Quadris Satori Equation 10-34-0 Starter

Azoxystrobin + 10-34-0 2 hours after mixing Quadris Satori Equation 10-34-0 Starter

Seed vs In-furrow fungicides - 2015 Treatment No. harv. Roots/100 ft. RCRR (0-7) Yield RSA Seed treatments 98 3.9 20.1 6181 In-furrow treatments 127 2.7 25.5 7772 Contrast analysis p- value 0.001 0.006 0.0032 0.0148 Seed Treatments 14 g Kabina ST Metlock Suite Met. Suite + 7 g Kabina 7 g Kabina ST 2 g Vibrance In-furrow 12 fl oz Headline IF 10 fl oz Quadris IF 10 fl oz Equation IF 10 fl oz Satori IF NS = not significantly different

Seed vs In-furrow fungicides - 2016 2016 250 No. of plants per 100 ft. row 200 150 100 50 0 In-furrow fungicides Seed treatments Untreated control 0 7 14 21 28 35 42 49 Days after planting Planted late June

Seed vs In-furrow fungicides - 2016 Treatment No. harv. RCRR RCRR % Yield roots/100 ft (0-7) incidence ton A -1 RSA Mean of Seed trts. 105 2.9 19.8 16.1 3915 Mean of In-furrow trts. 126 1.5 7.1 17.5 4522 Contrast analysis P- value 0.0006 0.0001 0.0008 0.0152 0.0026 Seed Treatments 14 g Kabina ST Metlock Suite Met. Suite + 7 g Kabina 5 g Systiva 1.5 g Vibrance In-furrow 9 fl oz Headline IF 10 fl oz Quadris IF 10 fl oz Satori IF Xanthion (Headline + Integral, 9 + 1.8 fl oz/a)

Seed vs In-furrow fungicides - 2017 2017 No. of plants per 30 m of row 250 200 150 100 50 0 Seed treatments In-furrow fungicides Untreated control 0 7 14 21 28 35 42 49 Days after planting

Seed vs In-furrow fungicides - 2017 Treatment No. harv. RCRR Yield ton roots/100 ft (0-7) A -1 RSA Seed treatments 195 1.2 31.6 10708 In-furrow treatments 191 0.8 32.4 11132 Contrast analysis P- value Seed Treatments 14 g Kabina ST Metlock Suite Met. Suite + 7 g Kabina 5 g Systiva 1.5 g Vibrance 0.43 0.07 0.36 0.22 NS NS NS NS In-furrow 10 fl oz Quadris 11.9 fl oz AZteroid Xanthion (Headline + Integral, 9 + 1.8 fl oz/a) NS = not significantly different

Seed vs In-furrow fungicides - 2018 180 160 140 No. plants/100 ft of row 120 100 80 60 40 Seed treatments In-furrow treatments Untreated control 20 0 0 7 14 21 28 35 42 49 56 Days after planting Planted early May

Seed vs In-furrow fungicides - 2018 Treatment No. harv. RCRR Yield ton roots/100 ft (0-7) A -1 RSA Seed treatments 151 0.7 32.8 10440 In-furrow treatments 141 0.4 32.2 10528 Contrast analysis P- value Seed Treatments 14 g Kabina ST Met. Suite + 1 g Vibrance Met. Suite + 7 g Kabina 5 g Systiva 1.5 g Vibrance 0.01 0.01 0.5 0.5 NS In-furrow 9.5 fl oz Quadris 11.9 fl oz AZteroid NS Xanthion (Headline + Integral, 9 + 1.8 fl oz/a) Elatus 9.5 fl oz (* not registred for sugarbeet) NS = not significantly different

Management of Rhizoctonia Early planting Crop Rotation Crop choice Length of rotation Weed control Resistant varieties At-planting fungicides Seed treatment In-furrow application Postemergence fungicides

4-inch soil temp daily means 100 90 80 70 65 F 65 F 60 50 NWROC Wahpeton Renville 40 1-May 8-May 15-May 22-May 29-May 5-Jun 12-Jun 19-Jun 26-Jun 3-Jul 10-Jul 17-Jul 24-Jul 31-Jul 7-Aug 14-Aug 21-Aug 28-Aug 4-Sep 11-Sep 18-Sep 25-Sep Mean 4-inch soil temperature

Postemergence Application 2017 Quadris in a 7-inch band

Postemergence fungicides 2015 Quadris vs Generics RCRR Yield RSA Treatment (0-7) T/A Non-inoculated No-fungicide control 3.4 24.3 6263 R. solani-inoculated Equation @ 14 fl oz/a 1.9 d 31.0 a 8066 a Quadris @ 14 fl oz/a 2.4 d 29.9 a 7908 a Satori @ 14 fl oz/a 2.4 d 29.6 a 7790 a No-fungicide control 5.5 a 14.0 c 3411 c ANOVA P-value 0.0001 0.004 0.002 LSD (P = 0.05) Z 1.4 8.3 2284

Postemergence fungicides 2015 Band vs Boradcast Treatment (Rates per Acre) RCRR (0-7) RCRR % Incidence Yield T/A RSA No fungicide control 3.7 a 75 a 23.2 c 7324 c AZteroid @ 17.6 fl oz, 0.7 b 15 b 33.6 ab 11084 ab band Quadris @ 10 fl oz, band 0.9 b 16 b 33.5 ab 11272 a Quadris @ 14 fl oz, band 1.2 b 25 b 31.9 ab 10659 ab Quadris @ 14 fl oz broadcast 1.1 b 21 b 33.4 ab 10944 ab ANOVA P-value <0.0001 <0.0001 <0.0001 0.0001 LSD (P = 0.05) W 0.92 18.4 3.86 1451

Cultivar x postemergence interaction 30 on disease incidence - NWROC % RCRR incidence 25 20 15 10 5 0 Resistant Susceptible (4.0) (4.8) Untreated 4-leaf 8-leaf Postemergence application

Cultivar x at-planting x postemergence interaction on disease incidence - SMBSC % RCRR incidence 80 70 60 50 40 30 20 10 0 Resistant cultivar Untreated 4-leaf 8-leaf Quadris Systiva Untreated At-planting treatment % RCRR incidence 80 70 60 50 40 30 20 10 0 Susceptible cultivar (4.0) (4.8) Untreated 4-leaf 8-leaf Quadris Systiva Untreated At-planting treatment

Benefits Postemergence fungicides If you are doing a row cultivation--throwing soil onto crowns Late season disease control (rain aug-sept) If sugarbeets are following Rhizoctonia-susceptible crops in a rotation Band application (preferred) severe disease pressure Broadcast application low disease pressure Risks Work better if applied before infection

Take Home Message for 2019 Rhizoctonia risk (beets/100 ft. row at harvest) Your Variety choice Seed treatment In-furrow treatment Postemergence treatment Low (170-200) Moderate Weak Yes Yes No No No Yes Specialty < 4.0 Rhizoctonia rating Moderate 4.0 4.4 Weak > 4.4

Take Home Message for 2019 Rhizoctonia risk (beets/100 ft. row at harvest) Your Variety choice Seed treatment In-furrow treatment Postemergence treatment Low (170-200) Moderate Weak Yes Yes No No No Yes Moderate (130 170) Specialty Moderate Weak Yes Yes Yes No No No Yes/No (History) Yes Yes

Take Home Message for 2019 Rhizoctonia risk (beets/100 ft. row at harvest) Your Variety choice Seed treatment In-furrow treatment Postemergence treatment Low (170-200) Moderate Weak Yes Yes No No No Yes Moderate (130 170) Specialty Moderate Weak Yes Yes Yes No No No Yes/No (History) Yes Yes Severe (less than 130) Specialty Moderate Weak Yes Yes Yes No Yes Yes Yes Yes Yes

Summary- Rhizoctonia Management Seed treatments provide excellent early-season protection In-furrow applications Similar to seed treatments under low disease pressure Better than seed treatments under high disease pressure May reduce stands under cool and dry soil conditions Seed/in-furrow treatments can broaden the window to apply postemergence application (4 to 8 leaf stage) Postemergence application is most beneficial under moderate to heavy disease pressure especially if beets are following soybeans or edible beans Generic formulations of azoxystrobin are effective

Acknowledgements Sugarbeet Research and Education Board of Minnesota and North Dakota Grower cooperators Scott Pahl, Germains Seed Technology Seed, chemical, and allied industries American Crystal Sugar Company quality lab Minn-Dak Farmers Cooperative Southern Minnesota Beet Sugar Cooperative

Thank you! Jason Jeff Pratibha Hal Katie Alec Claire Karen Tim Muira Brandon Amanda Dr. Ian MacRae Tim