Disease Management in Soybeans. Sam Markell, Ph.D. Extension Plant Pathologist

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2 Disease Management in Soybeans Sam Markell, Ph.D. Extension Plant Pathologist

3 Diseases of Soybean Leaves Hardly enough to think about Stems Enough to think about Roots Enough to actively manage

4 Root Rots Take Home Messages Will increase over time Soybean Cyst Nematode Sample for it Its coming Foliar Fungicide Applications Yield benefit? White mold Not as devastating as in other crops

5 Root Rots

6 Soil moisture Soil temperature Pythium Flooded Cool (50-60 F) Phytophthora Flooded Warm (70s F) Fusarium Wet to dry Cool to warm Rhizoctonia Damp to wet Warm (70-80s F) Adapted from Robertson et al.

7 True Fungi Fusarium Dry Rot General Browning Rhizoctonia Dry Rot Red Cankers Photos Carl Bradley

8 Not true Fungi Black/wet lesions Need Wet Soil! Photo: U of Wisc Photo: Berlin Nelson

9 Courtesy of Dr. Tom Chase, South Dakota State University

10 Courtesy of Dr. Tom Chase, South Dakota State University

11 Root Rot Management Rotation Resistance genes to Phytophthora Seed Treatments Broad Spectrum Effective for several weeks Help germination and stand establishment

12 2003/04 Trial s Conducted by Bradley / Helms 8 and 6 locations Variety had rps 6 Lsd = 1 Warden RTA (fludioxonil + mefenoxam, Agriliance) SoyGard (azoxystrobin + metalaxyl, Gustafson) Yield Shield biological seed treatment (Bacillus pumilus, Gustafson)

13 Soybean Seed Treatment Study Great Bend, Richland Co.

14 Soybean Cyst Nematode

15 Soybean Cyst Nematode (SCN) #1 Soybean Disease in United States It will spread into Manitoba

16 Marett & Tylka 1954

17 Soybean Cyst Nematode (SCN) Yield reductions (15-30%) before above ground symptoms are present Once in soil you will have it forever

18 Soybean Cyst Nematode (SCN) We can manage this if. You look for it Find it early Keep egg levels low

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20 Cysts Nodule

21 Soybean Cyst Life Cycle Source:

22 Why is the Cyst Important? Soybean Cyst Life Cycle Tough structure Long term survival Moves with soil Equipment, Water, Wind, Birds, Boots, 4-wheelers, etc.. Source:

23 Soybean Cyst Life Cycle Source:

24 Why is Mating Important? High genetic Soybean diversitycyst Life Cycle Ability to change/adapt Source:

25 Soybean Cyst Life Cycle Source:

26 Soybean Cyst Life About Cycle 4 weeks Source:

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28 Richland County, ND

29 Impacts of SCN Takes away nutrients Water update disrupted Interferes with nodulation

30 How does SCN move?

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34 Texas dust storm

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37 Where is SCN?

38 SCN Survey Grower based sampling Soil sample bags distributed at County offices Distributed at SCN field days Cost covered by the ND Soybean Council Sent to the lab Data reported in egg counts

39 McGawley, Louisiana State University McGawley, Louisiana State University

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42 EFFECT OF SCN ON GROWTH OF DRY BEAN (Courtesy Berlin Nelson) Pinto bean field experiment in ,000 EGGS/100 CC SOIL CONTROL 10,000 EGGS/100 CC SOIL

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44 Low levels may/may not be false positive

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47 Looking for SCN?

48 40%

49 Rotation Recommendations SCN Hosts Dry Edible Beans Chickweed Field Pennycress Purselane Shepard s Purse Sweet Clover Wild Mustard Nelson

50 Plant Health Sam Markell, Ph.D. Extension Plant Pathologist

51 Plant Health Physiological yield benefits in the absence of disease Yield bump has been observed Predictable? Reliable?

52 Soybean Fungicide Trials (Markell, Endres, Schatz, Halley) Headline (plus NIS) Nontreated LSD Rate (fl oz/a) Crop stage Yield(bu/A) Yield(bu/A) Fargo 12 R NS 2005 Carrington 3 and 6 V2/R * 6 R NS 2005 Fargo 6 R NS 6 R NS 9 R NS 2006 Carrington 3 and 6 V3/R NS 6 R NS 2006 Colfax - Small Plot 6 R * 2006 Colfax - Large Plot 6 R NS

53 White Mold

54 White mold Fungal pathogen Sclerotinia sclerotiorum Yield loss possible Manage with an Integrated Strategy Sunflower Dry Edible Beans Canola Soybean Other Pulse Crops Flax

55 Sclerotia Canola Council Canada White Mold) Disease Cycle Apothecia Venette Ascospores use dying petals for energy source Lamey Markell Ascospores land on fallen petals

56 Conditions Favorable for White Mold Before Bloom Moist soil 1-2 inches rain 1-2 weeks before bloom During bloom Heavy and prolonged dews Temps between 59 o and 75 o Above 85 o is unfavorable

57 Rotation Managing White Mold Important, especially for other crops in rotation Cereals and corn good options Cultural Practices Tillage..? Row spacing..

58 Managing white mold Cont.. Fungicides Economic return..? If conditions are very favorable Protect the crop at early bloom (R2) Resistance Partial Resistance can be effective

59 Percent Incidence / Yield Incidence Yield Variety

60 Percent Incidence / Yield Variety

61 Percent Incidence / Yield Variety

62 S C L E R O T I N I A M A N A G E M E N T I N S O Y B E A N S Fungicide efficacy CARRINGTON, ND (2013) Variety: Dairyland DSR 0404 R2Y Row spacing: 14 inches Application A: July 27; shortly before canopy closure at R2 growth stage Application B: August 8; early R4 growth stage Application methods: 15 gal water/a; 35 psi; 8001VS flat-fan nozzles

63 Google - Carrington REC Left hand column plant pathology

64 Resources Google - Carrington REC Holly Derkson holly.derksen@gov.mb.ca Mario Tenuta mario.tenuta@umanitoba.ca Sam Markell (701) samuel.markell@ndsu.edu

65 Thank You! Questions?

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