The first few people who tried to burn down annual ryegrass as a cover crop realized it wasn't like trying to control wheat or cereal rye. Annual ryegrass is a forage crop, and it has roots several feet deep into the soil. The challenge for those who will try burning it down in the next six to eight weeks is understanding herbicide characteristics and plant physiology.
This is one time when listening to those who have learned through the school of hard knocks, or who passed their knowledge along to other experts, will pay. Hans Kok of the Conservation Cropping Systems Initiative says that while annual ryegrass can be the toughest of most covers to kill, it can be done successfully.
The problem is that you're applying glyphosate at a time of year when it doesn't tend to be as effective on a sturdy plant that isn't yet actively growing and translocating materials to the roots. For glyphosate to take out ryegrass, it must reach the roots.
Increase your chances by checking the hardness and pH of your water, Kok says. Indiana water tends to be hard. The label recommends adding ammonium sulfate to the glyphosate mix. Limit the volume applied with water to about 10 gallons per acre, stay away from drift retardant nozzles since hardly anything else except wheat for a wheat crop is up and growing, and choose flat fan nozzles so you get a medium size droplet. The idea is to get as much coverage as possible.
You also want a pH of about 5.0. There are commercial products available that you can add to lower pH levels in the water, Kok says. You can find the test strips you need to check hardness and pH at a pool supply store.
Look for more tips on controlling annual ryegrass in the next Web item, and in the March issue of Indiana Prairie Farmer.
Thinking About A Cover Crop? Start With Developing A Plan
Taking time to design your cover crop plan will increase the successful establishment of the crop and potentially allow for improved staggering of fall harvest.