Weeds pose a serious threat to Oregon agriculture. They reduce yields, lower seed and grain quality, and can keep shipments from meeting market standards. This challenge is statewide although its impacts vary by region.
The statewide assessment provides the roadmap to target research, testing and Extension education where they will deliver the greatest benefit.
In Western Oregon’s grass seed systems, growers struggle with annual bluegrass, Italian ryegrass and roughstalk bluegrass. In Eastern Oregon’s dryland wheat, downy brome and Russian thistle are persistent problems. Costs are rising as more weeds develop herbicide resistance, reducing the effectiveness of spray programs and leaving growers with fewer effective tools.
Oregon lacked a statewide snapshot of which weeds cause the most harm, what weed control costs look like, and which tools and trainings would help the most. Without that picture, it was hard to target research and Extension efforts where they would have the biggest impact.
Oregon State University Extension Service faculty seek input from industry to help shape and prioritize their Extension and research priorities. Victor Ribeiro, Extension specialist in weed science, led the first statewide needs assessment focused on weed management in field crops.
Ribeiro, an assistant professor in the Department of Crop and Soil Science in the College of Agricultural Sciences, designed an eight-question survey and shared it through industry groups, OSU Extension Service meetings and social media from October 2024 to February 2025.
The survey results are published in the journal Weed Technology. A total of 184 people responded, most of them growers and crop consultants from across the state. The survey asked about problem weeds, weed control costs, concern about herbicide resistance, and preferred ways to receive information and training.
Because 74% of responses came from Western Oregon, the results reflect that region more strongly.
The survey produced clear, actionable guidance for research and outreach:
- Annual bluegrass, Italian ryegrass and roughstalk bluegrass were the most reported grass weeds. Wild carrot was the leading broadleaf concern. Regional patterns were distinct — ryegrass and bluegrass dominated in Western Oregon, while downy brome and Russian thistle were more common in Eastern Oregon.
- Most respondents reported weed control costs of $125 to $250 per hectare. Added labor for hand-pulling and spot spraying, along with repeat applications when products fail, contributes to higher costs.
- 58% of respondents said they are very concerned about resistance and 39% are somewhat concerned. Several key species in Oregon have populations that no longer respond to commonly used herbicides.
- The most requested support was new herbicide technologies. Many also asked for nonchemical approaches and more information on weed biology and integrated strategies. For learning, field days were the top choice, followed by workshops, webinars and website posts — a mix that supports both hands-on and flexible options.
The findings help OSU Extension and the Oregon Agricultural Experiment Station focus efforts that matter most to growers and advisors:
- Concentrate research and demonstrations on annual bluegrass, Italian ryegrass, roughstalk bluegrass and wild carrot.
- Expand herbicide evaluation and resistance monitoring so growers know what works, where and why.
- Promote integrated weed management — combining cultural, mechanical and chemical tactics to slow resistance and protect yields and quality.
- Deliver information in the ways stakeholders prefer, with strong field-day programming supported by workshops, webinars and practical online resources.
With this statewide assessment, Ribeiro provides the roadmap to target research, testing and Extension education where they will deliver the greatest benefit — helping Oregon producers protect crop value, meet market standards and keep farms productive for the long term.