Controlling Winter Annual Bromes in Pastures with Herbicides

Controlling Winter Annual Bromes in Pastures with Herbicides April 1, 2016

Cheatgrass, downy brome, wild oats. Last fall’s moisture is making these early weeds a big problem in pastures this spring, reducing pasture quality and carrying capacity.

What can you spray to get rid of winter annual weeds like these?

Before deciding to spray, realize that the seed of these grasses lasts several years in the soil. That means you need to plan to repeat any spraying for at least a couple years.

In pastures dominated by warm-season grasses, one option is to spray 1 pint per acre of glyphosate, like Roundup®, early this spring after the weedy bromes green up but before warm-season grasses start growing.  This should solve the problem for this year and knock out other early weeds like bluegrass without harming your warm-season grasses.

Another option is to use 4 to 6 ounces of Plateau herbicide or its generics and get similar results. With Plateau, residual herbicide activity also will control some later emerging weeds.

If your pasture is cool-season grass, the job is tougher. Both glyphosate and Plateau harm cool-season grasses. Gramoxone may be a better choice but don't spray until the weedy bromes are about to form seed heads. Gramoxone will kill all the green top growth it contacts. This includes your good grass; good perennial grasses will start to regrow after a couple of weeks while the weedy grasses will be killed, eliminating their seed production this year. Obviously, this is a pretty drastic choice so use it only in your worst pastures.

Once you’ve gotten rid of the weeds, be sure to graze in ways that maintain the vigor and competitiveness of your desired grasses.