Close-up of horseweed.

Weed Resources

Save the date for the 2024 WSU Weed Tour

June 12, 2024

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Featured Video and Articles

Integrated weed management (IWM) strategies are critical for effective long-term management of weeds in the agroecosystem. This video summarizes the biological framework for integrated weed management and summarizes an approach to developing a weed management plan.
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Pacific Northwest Herbicide Resistance Initiative

The Pacific Northwest Herbicide Resistance Initiative (PNWHRI) provides ongoing support for programs and projects focused on managing herbicide-resistant weeds across the PNW, with a special focus on cereals producing regions.

Think you know PNW weeds? See how well you do with our fun weed quiz.

Common WEEDS

Herbicide RESISTANCE Resources

Herbicide-resistant weeds are becoming increasingly common in the Pacific Northwest, threatening the economics and sustainability of farming systems. Herbicide-resistant weed biotypes are selected for and will increase in the population through repeated use of the same or similar herbicides. Italian ryegrass, downy brome, wild oats, Russian thistle, mayweed chamomile, and prickly lettuce are just a few of the many weed species with biotypes resistant to commonly used herbicides. The resources on this page will help you understand how herbicide resistance occurs, how to manage weeds to slow the rate of herbicide resistance development, and what to do if you suspect you have a resistant biotype on your farm.

Save the date for the WSU Weed Tour: June 12, 2024

Best Management Practices for Managing Herbicide Resistance (PNW754)

Abstract: Herbicide resistance is a problem that has quickly spread throughout the wheat-growing regions of the inland Pacific Northwest. Over-reliance on herbicides for the management of weeds is a major cause of herbicide resistance. Integrated weed management relies on a wide range of practices to manage weeds and slow the development and spread of herbicide resistance. This publication presents growers and farm managers with best management practices (BMPs) that can be incorporated into farming systems to manage herbicide resistance. A table toward the back of the publication (Table 3) allows readers to identify practices that are already being used and additional practices that should be implemented.

Resistance Testing Program

Submitting a sample to the WSU Resistance Testing Program is easy. View the Resistance Testing Program webpage for details about how to submit samples.

GROW is a scientist-led network coordinating research to help farmers across the U.S. fight herbicide-resistance with a greater diversity of weed control strategies. The GROW website and social media platforms provide information, videos, tools, news stories and other resources on integrated weed management options such as cover crops, increased crop competition, harvest weed seed control, weed seedbank prevention and more.

Weed Decision TOOLS & Calculators

Wheat Mechanisms of Action (MOA) Tool

Query a database of herbicide trade names, active ingredients, mechanisms of action, and Washington weed species with confirmed resistance to one or more herbicides.

Herbicide Resistant Weeds Map

See what herbicide-resistant biotypes have been identified in counties in eastern Washington and adjoining counties in Idaho and Oregon. 

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