What we can learn from 2019? This talk will look at agronomic warning signs and ways to be proactive going forward. Christine O'Reilly, OMAFRA

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

3. What happened?
3 Winterkill Woes

4. What happened?
4 Winterkill Woes

5. 5 PresentationName

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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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/

17. 17 PresentationName

18. 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

19. 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

20. 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

21. 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

22. 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

24. 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

25. 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

26. 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

27. I stole this slide fromJake Munroe

28. 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

29. Winterkill Woes
Which Risk Factors Can You Control?
Respect the fall rest period
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30. How forage plants grow
Forage crops grow
leaves before they refill
their root reserves

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

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

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

34. 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!

35. 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