Timing Key To Bringing Down Annual Ryegrass Cover Crop

Expert offers tips on burndown that kills this cover.

Published on: Feb 23, 2012

If you've got annual ryegrass in the field as a cover crop and are getting nervous as spring approaches, likely because it's you've heard horror stories about how hard it can be to kill to plant into with no-till planting in the spring. You aren't worried about getting the benefits, including deep rooting that helps loosen soils and nitrogen capture for later release, and that's what led you try annual ryegrass in the first place. Will you be able to burn it down and kill it when it's time to switch to planting mode.

Mike Plumer, a former University of Illinois agronomist who has researched cover crops for decades, says that you can, and that you shouldn't be afraid of it. Instead, determine that you are going to manage it and move forward. Plumer's decades of experience with no-till and cover crops on his own farm in southern Illinois add to his credibility as someone who knows what they're talking about when it comes to the benefits and challenges of cover crops.

The secret to bringing down annual ryegrass in a timely manner is understanding the plant and the chemicals you are applying to kill it, he says. Most people use glyphosate. To work glyphosate must be translocated in to the roots of the plant. These applications are often made during cool weather in the spring. Glyphosate doesn't work as well when it is cool because it doesn't translocate as well. This is not a place where you want to cut herbicide rates.

The biggest tip Plumer offers is to pick the warmest day you can find that features lots of sunshine. Don't spray before 8:30 t0 9 a.m. in the morning. The most crucial part is when you stop spraying annual ryegrass. He suggests that you shut down applying glyphosate by 1 p.m.

Here's why. Ryegrass itself stops translocating materials around 3:30 to 4 p.m. in the afternoon. You want to allow a four-hour window for the product to work if at all possible. So late evening or very early morning applications are doomed for success rate from the start.

Learn more in a series of articles about cover crops in the April issue of Indiana Prairie Farmer  magazine. Plumer will share more tips about managing and killing other types of cover crops.