Herbicide resistance is one of the most pressing issues facing Pacific Northwest (PNW) farmers. Because weeds continually evolve to survive current herbicide technologies and practices, managing herbicide resistance now requires more than new chemistry. It takes collaboration, creativity, and commitment across state lines. That unified effort is exactly what the Pacific Northwest Herbicide Resistance Initiative (PNWHRI) hopes to achieve.
Launched through the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) and the region’s three land-grant universities — Washington State University, Oregon State University, and the University of Idaho — the PNWHRI brings together more than 25 scientists, extension specialists, and industry partners. Funding support also comes from grower commissions and commodity organizations across Idaho, Oregon, and Washington, including the Washington Grain Commission (WGC).
The initiative’s overarching goal is simple but ambitious: to reduce the threat of herbicide-resistant weeds across the PNW’s cereal-based cropping systems and safeguard the long-term productivity, profitability, and export reliability of regional grain.
From monitoring weed seedbanks to applying machine learning, PNWHRI’s research network spans experimental farms and farmer-cooperator fields across all three states. The 2024 Annual Report highlights major achievements:
- Rotation and seedbank studies. Long-term trials in Washington, Oregon, and Idaho show that diversified rotations — especially those including alfalfa — can reduce weed seedbanks by up to 94%, providing a proactive tool against resistant populations.
- Resistance surveys. Regional screening has confirmed widespread resistance in species like downy brome, Italian ryegrass, and Palmer amaranth, underscoring the urgency of integrated management.
- Technology and innovation. New tools such as machine-learning weed-seed identification, infrared seed-deactivation systems, and GIS-based resistance mapping are giving researchers and farmers better data and faster decisions.
- Co-innovation with growers. Farmer led “co-innovation” groups are testing harvest weed seed control mills and exploring new rotational crops like grain sorghum for dryland systems.
At this year’s PNWHRI annual meeting in Moscow, Idaho, Casey Chumrau, WGC CEO, represented the commission and experienced the initiative’s collaboration firsthand. “Washington, Oregon, and Idaho researchers, extension professionals, and
industry partners are fully committed to this unified effort. No one is working in isolation,” Casey said. “The diversity of approaches shows just how multifaceted our fight against herbicide-resistant weeds has become.”
Casey also expressed appreciation for long-time contributors, Dr. Ian Burke and Dr. Drew Lyon, whose work has shaped PNW weed-science programs for more than a decade. Both will be moving on to new opportunities by the end of 2025, leaving a lasting legacy of innovation and mentorship in regional weed management.
Through continued research, grower engagement, and shared commitment, the PNWHRI is positioning the Pacific Northwest as a national model for collaborative, science-based solutions to herbicide resistance. To explore ongoing projects, partners, and resistance-tracking maps at the county level, visit pnwhri.org
This article originally appeared in the November 2025 issue of Wheat Life Magazine.
Jake Liening
Marketing Development Specialist, Washington Grain Commission