Burndown Herbicide Programs and Weed Potential of Cover Crops

1. Burndown Herbicide Programs and Weed Potential of Cover Crops Rich Hoormann EC Region Agronomist

2. Cover Crops and Weed Potential • Rye • Wheat • Oats • Red clover • White clover • Lespedeza • Medics • Crimson clover • Other legumes • Hairy vetch • Rape • Radish • Turnips • Winter peas • Brassica • Annual ryegrass • Summer annual grasses • Barley

3. Burndown Recommendations

4. Purdue University: Keith D. Johnson Forage Specialist

5. 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

6. 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 14-21 days after the glyphosate. Atrazine also needs rain to activate. Cornell

7. Annual Ryegrass Control as Influenced by Rate and Application Timing(graph adapted from Lins et al. 2005)

8. 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).

9. Competition of Ryegrass Michael Plumer Natural Resources Management

10. Determine Growing Point

11. Timing of Burndown & Adjuvant

12. Purdue University: Keith D. Johnson Forage Specialist

13. 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

14. 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

15. 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

16. Balance is difficult Balance is difficult

17. Thanks for your time