Controlling Winter Annual Bromes This Fall

By Bruce Anderson

Extension Forage Specialist

Did you have downy brome, cheatgrass, or wild oats in your pasture this spring?  Although difficult, they can be controlled and your pasture revitalized.

Winter annual bromes often invade thin or overgrazed pastures in fall and early spring.  Livestock dislike grazing them, so over time they can take over and make large patches of pasture nearly worthless.

By far the most effective control method is to spray six to eight ounces per acre of an imazapic herbicide like Plateau as soon as possible in September.  This pre-emerge treatment will prevent most annual bromes from developing.

As we move into October, however, it is likely that some, or maybe a lot of these grass seedlings will have already emerged.  When this situation exists, add an adjuvant like a non-ionic surfactant or methylated seed oil to the spray mix for better control of emerged seedlings.

In warm-season grass pastures and rangeland, there is another option.  You can use glyphosate herbicides after top growth of these grasses has died due to a hard freeze or two.  This can kill emerged annual brome seedlings without harming the desirable grasses.  However, do not use glyphosate in cool-season pastures because it will injure or kill the pasture grasses as well.

These treatments may need to be repeated for a couple years to prevent reoccurrence of these weedy grasses.  But with proper grazing management and other practices, your pastures can develop thicker stands of the more desirable grasses.

It takes a long, dedicated process to recover pastures overtaken by winter annual bromes.  There are no shortcuts.

Source:unl.edu