7. Forage Winterkill Woes

1. Winterkill Woes What we can learn from 2019 Eastern Ontario Crops Conference Kemptville, ON February 11, 2020 Ontario Ministry of Agriculture, Food and Rural Affairs

2. What happened? 2 Winterkill Woes

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6. Scouting for Vigour Plant Counts – your early warning system Stand Age Healthy Plants/Foot2 New seeding 20+ Year 1 12 - 20 Year 2 8 - 12 Year 3 or older 5 6 Winterkill Woes

7. Alfalfa Stand Assessment Photo:J. Bagg 7 PresentationName

8. Scouting for Vigour Stem Counts – your yield potential Yield Potential Stems/Foot2 100% 55+ 75% to 92% 40 - 50 Not worth keeping <40 9 Winterkill Woes

9. Which Risk Factors Can You Control? Select disease-resistant varieties • Bacterial wilt • Verticilliumwilt • Fusarium wilt • Anthracnose • Phytophthoraroot rot • Aphanomyces root rot (race 1) • Aphanomyces root rot (race 2) 10 Winterkill Woes DRI = 30 DRI = 35

10. Bacterial wilt • < 58% yield loss • Older stands (3+) • Cut uninfectedfields first to reduce spread 11 Photo: Alfalfa Diseases II, Plant Disease No. 8, January 1980

11. Verticillium wilt • < 50% yield loss • Shortens stand life • Typically visible in 2nd year stands • Found all over Ontario • Spores spread on harvestingequipment and in livestock manure.12 Photos:Unknown #FromTheFilingCabinet

12. Fusarium wilt • Similar appearance to Verticilliumwilt • Root rot tends to be darker than Verticilliumwilt-causedrot 13 Photos:Alfalfa Diseases II, Plant Disease No. 8, January 1980

13. Anthracnose • < 25% yield loss • Crown damage reduces stems and kills plant • Clean harvest equipmentbetweenfields to minimize spread 14 Photo: Alfalfa Diseases II, Plant Disease No. 8, January 1980

14. Phytophthora Root Rot • Usually seedling disease, weakens plants that survive • Shortens stand life • Across ON in heavy clays and poorly drained fields • Drainage & good fertilityhelp reduce impact 15 Photos:G. Peng, 1994

15. Aphanomyces Root Rot (Races 1 and 2) • Seedling disease, reduces productivity of surviving plants • Improving drainage and reducing soil compaction help mitigatesymptoms 16 Photo: https://fyi.extension.wisc.edu/forage/aphanomyces-root-rot-in-alfalfa/

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17. Which Risk Factors Can You Control? Fertilize the crop as recommended! • Current soil test (<3 years old) • Economic response to fertilizerbelow 12 ppm P or 120 ppm K • Potassiumis important for winterhardiness 18 Winterkill Woes

18. Phosphorus and alfalfa P is critical for roots and energy Deficiency shows as slowed growth, spindly plants, small dark blue- green leaves Low soil P negatively affects winter survival Arizona College of Agriculturaland Life Sciences – Cooperative Extension I stole this slide from Jake Munroe

19. 0 0.2 0.4 0.6 0.8 1 1.2 0 5 10 15 20 25 30 35 40 RelativeYield Na BicarbonateextractableP (Olsen) Relative Yield of Forages at various P soil tests Sheard, UG, 1980sI stole this slide fromJake Munroe

20. Potassium and alfalfa K – critical for enzymes, water regulation and winter survival Deficiency shows as yellow/white spots along leaf margins (older leaves) Subject to luxury consumption I stole this slide from Jake Munroe

21. 0 0.2 0.4 0.6 0.8 1 1.2 0 50 100 150 200 250 300 350 RelativeYield AmmoniumAcetate Extractable K Forage Yield Response to K at various soil test levels Sheard, UG, 1980sI stole this slide fromJake Munroe

22. Luxury Consumption and Dairy Dietary K above2% for dry and transitioncows predisposesthem to milk fever • Over-fertilizingincreases K concentration • At the same stageof maturity, grasses and legumes contain the same amount of K, except silage corn • K concentrationdeclines as plants mature • K will leach out of rained-on forage 24

23. Luxury Consumption and Dairy A = 50 lbs/acre P2O5 + 0 K2O B = 100 lbs/acre P2O5 + 300 lbs/acre K2O C = 100 lbs/acre P2O5 + 0 K2O D = 150 lbs/acre P2O5 + 100 lbs/acre K2O E = 50 lbs/acre P2O5 + 300 lbs/acre K2O 25 Source: Perdue Extension,FactsheetAY-331-W PhosphorusandPotassiumFertilizationofAlfalfa

24. Sulphur and alfalfa High uptake and removal: >5 lbs S/ton Early season demand – impact of cool, wet spring? Deficiency can have significant effect on yield I stole this slide fromJake Munroe

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26. Sulphur deficiency diagnostics Soil test – not reliable; not calibrated for Ontario Tissue test: <0.25% S indicates deficiency • Top 6 inches at mid-bud – early flower 0.34% S 0.18% S I stole this slide fromJake Munroe

27. Winterkill Woes Which Risk Factors Can You Control? Respect the fall rest period 29

28. How forage plants grow Forage crops grow leaves before they refill their root reserves

29. Which Risk Factors Can You Control? Scout to stay ahead of problems 31 Winterkill Woes

30. Other Forage Crops Birdsfoot Trefoil • Fall rest period starts 10 days earlier than alfalfa 32 Winterkill Woes

31. Other Forage Crops Orchardgrass • Historicallywinterkills25% of the time • Less persistenton wet soils 33 Winterkill Woes

32. Take Home Messages • Scout early and often! • Choose disease resistantcultivars to maintain yield and persistencepotential • Feed your alfalfa well so it can feed your livestock well • Respect the fall rest period • Scout early and often!

33. Christine O’Reilly Forage and Grazing Specialist Ontario Ministry of Agriculture, Food and Rural Affairs 322 Kent Street West, Room 105 Lindsay, ON, K9V 4T7 705-341-4899 christine.oreilly@ontario.ca Twitter: @OReilly_Ag www.fieldcropnews.com