Burndown Herbicide Programs and
Weed Potential of Cover Crops
Rich Hoormann
EC Region Agronomist
Cover Crops and Weed Potential
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Rye
Wheat
Oats
Red clover
White clover
Lespedeza
Medics
Crimson clover
Other legumes
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•
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Hairy vetch
Rape
Radish
Turnips
Winter peas
Brassica
Annual ryegrass
Summer annual grasses
Barley
Burndown Recommendations
Hairy Vetch
Red Clover
Crimson Clover
Alfalfa
Annual rye
winter wheat
No-Tillage burndown
Herbicide
Cover Crops
2,4-D
0
0
7
8
8
9
Aim
1
0
-
-
-
-
Aatrex
6
6
4
3
5
7
Balance Pro
-
-
-
-
-
-
Bavnvel/Clarity
0
0
9
8
9
9
Basis
-
5
5
5
5
5
Canopy EX
-
1
4
5
5
-
Distinct/Status
1
1
8
8
8
8
Glyphosate
9
9
4
3
6
6
Gromoxone Max
7
6
4
9
4
8
Sencor
9
9
4
3
5
5
Septer
4
4
3
2
5
3
Spartan
-
-
-
-
-
-
Valor
-
-
-
-
-
-
Valor XLT
-
6
4
4
4
-
Purdue University: Keith D. Johnson Forage Specialist
Annual Ryegrass Control
• Tillage very effective
• Mowing after
bloom/before complete
seed development
– Variable success
– Some seed may be
produced
• Plastic mulch smothered
– Smaller easier to control
•
Michael Plumer Natural Resources Management
Annual Ryegrass
• Annual ryegrass volunteers are particularly undesirable in small
grains, so special care must be taken if they are part of your
rotation. It can be controlled with tillage and/or herbicides. When
tilling, plow under and disk as soon as conditions permit.
• The timing of herbicide applications is important to control
ryegrass. Apply glyphosate at 3 pt/ac when the grass is 6-9 inches
tall, day temperatures are > 50 F and the weather is sunny.
• A second or third application may be necessary to burn down
ryegrass.
• Simazine can be added to the tank mix but requires rain to activate,
• Atrazine should not be tank mixed with other herbicides. Apply 1421 days after the glyphosate. Atrazine also needs rain to activate.
Cornell
Annual Ryegrass Control
as Influenced by Rate
and Application Timing
A. Ryegrass
Application
Timing
Late Tiller
Second Node
Boot
Early Flower
(graph adapted from Lins et al. 2005)
Roundup
Glyphosate
PowerMax
Rate (lb ae/A) Rate (fl ozs/A)
A. Ryegrass
Control (%)*
0.375
11
40
0.75
22
59
1.5
44
75
0.375
11
29
0.75
22
46
1.5
44
66
0.375
11
43
0.75
22
67
1.5
44
86
0.375
11
58
0.75
22
79
1.5
44
88
*Results summarized across 6 locations in 3 states
More Thoughts on Annual Ryegrass
(Lolium multiflorum) as a Cover Crop
• For control prior to corn, I would prefer to see a
burndown herbicide like glyphosate or Gramoxone
applied in combination with a photosynthetic inhibitor
like Atrazine or Princep
• Annual ryegrass is one of the worst weeds of wheat
production in the southeastern and mid-Atlantic states.
• Glyphosate-resistant biotypes of annual ryegrass occur
in Mississippi and Oregon (and other countries as well).
Competition of Ryegrass
Michael Plumer Natural Resources Management
Determine Growing Point
Timing of Burndown & Adjuvant
Purdue University: Keith D. Johnson Forage Specialist
Hairy Vetch
• WORDS OF CAUTION: Hairy vetch contains many hard
seeds with 15 to 30 percent common. These hard
seeds can remain in the soil for several years, then
germinate to develop into unwanted plants. Vetch is an
especially serious weed plant in wheat. Thus it should
never be permitted to mature and set seed.
• Glyphosate alone was relatively ineffective at
controlling hairy vetch in corn;
• (1) Paraquat, (2) Paraquat + 2,4-D, (3) Paraquat +
dicamba, (4) Glyphosate, (5) Glyphosate + 2,4-D, (6)
Glyphosate + dicamba, (7) 2,4-D, (8) Dicamba.
• California Data
Hairy Vetch control
• 2,4-D, Banvel or their mixtures should be used
• Note - if hormone sensitive crops are
following the cover crop, apply hormone
sprays in the fall to avoid injury. OMAFRA
Rye
• Control on time. Incorporate before seed set. May
regrow if tilled before boot stage, typically early May.
• Mow in the spring after all the tillers are past the boot
stage but before the plants have headed out.
• For no-till planting, roll at heading.
Wet warm spring weather can cause quick growth and
make incorporation difficult. Apply glyphosate at 1
lb/ac ai. for effective control of rye. Cornell
Balance is difficult
Thanks for your time