New Tool Helps Growers Identify Herbicide Mechanisms of Action

Herbicide resistant weeds are a growing concern in the Pacific Northwest, the US, and globally. One of the key tactics in the fight against herbicide resistant weeds is to alternate or combine herbicides with different modes of action; however, it is often difficult for growers to know what active ingredient(s) are in the jug they just bought and what mechanism(s) or mode(s) of action those active ingredients bring to the weed control effort.

There is a new tool available on the WSU Wheat and Small Grains website that allows growers to see what active ingredients are in the herbicides commonly used in wheat and barley production in Washington. The Herbicide Mechanisms of Action (MOA) tool allows growers to query a database of herbicide trade names, active ingredients, mechanisms of action, and Washington weed species with confirmed resistance to one or more herbicides. Growers can search by trade name to find out what active ingredient(s) are in a herbicide product, what mechanism(s) of action the active ingredient(s) represent, what chemical family each active ingredient is in, and whether there are any weed biotypes in Washington with confirmed resistance to that mechanism of action. The tool also allows growers to search the database by active ingredient, mechanism of action group, or resistant weed.

By knowing what active ingredients and mechanisms of action they are using, growers can do a better job of managing weeds in a way that slows the likely development of herbicide resistance in their weed populations. This is extremely important as there have been no new mechanisms of action introduced into the marketplace in more than 20 years. It is unlikely that any new herbicide mechanisms of action will be available soon to replace current herbicides when they stop working.

Contact Drew Lyon by email at or by phone at 509-335-2961 with your questions.
Washington State University