The Right Chemistry for Annual Ryegrass Termination

As mentioned in the last blog post, terminating annual ryegrass is a crucial step in the management of this cover crop. Here are some tips for making sure it’s done properly the first time:

1. Wait until the ryegrass has fully broken dormancy from the winter.

2. Apply in the daytime, when the temps are consistently above 55 degrees during the day. Best results occur when the soil temps are above 45 degrees. Apply during the day so as to give the plant a minimum of 4 hours of daylight – preferably in sunny weather…NOT with rain predicted – to absorb the herbicide (glyphosate).

3. Don’t scrimp on chemistry – apply glyphosate at 1.25-1.50 lb a.e./a with ammonium sulfate and surfactant before the end of April. Coming back again is both costly and risky…annual ryegrass can build a tolerance to glyphosate and you don’t want to tempt fate. Get it done right the first time.

Follow label directions carefully with respect to pH and mixing order. It is important when adding ammonium sulfate, buffering agents or water conditioners that they be added to the full spray tank of water and agitated for 3-5 minutes before adding the glyphosate. This is to ensure that the calcium, magnesium, iron and other dissolved minerals in the water do not interfere with the glyphosate activity.

5. Early termination of the cover crop makes control easier and reduces the amount of residue into which you’ll plant corn or soybeans. Early control also facilitates soil dry-down, allows for significant decomposition of annual ryegrass residue and release of nutrients for uptake by the corn or soybean crop.

6. Some growers have found it easier to plant into the annual ryegrass first and then apply a burndown. Warmer weather conditions improve glyphosate activity and planting into green vegetation has been successful, and is often easier than planting into a “half-dead” cover crop.

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