Is That Wheat or a Field of Cheatgrass?

Downy Brome in wheat field.

What happened? Wheat fields throughout Eastern Washington are full of downy brome (a.k.a cheatgrass). Many of those that aren’t, are full of Italian ryegrass. Why didn’t herbicides perform better than they did this year? Was it the weather, late applications, or are herbicide-resistant weed biotypes more prevalent than before? We would like to know the answer.

Dr. Ian Burke, with partial support from the Washington Grain Commission, has been screening weeds like downy brome and Italian ryegrass for resistance to commonly used herbicides for several years. The results of his screening can be found on the Herbicide Resistant Weeds Map (Be patient, it takes a while to download).

Screening of samples slowed during COVID, but Dr. Burke is gearing back up to screen more samples this year, and he is very interested to know if the poor performance of herbicides this past year, particularly for downy brome, was due to the spread of herbicide-resistant downy brome biotypes. If your herbicide program failed to control downy brome, please consider collecting some downy brome seed from your field and submitting it to the WSU Resistance Testing Program. Instructions for submitting samples can be found at the previous link. Visit the Herbicide Resistance Resources page on the Wheat and Small Grains website for more information on herbicide resistance and what you can do to manage the problem.

For questions or comments, contact Dr. Ian Burke via email at or Dr. Drew Lyon at