Brief Summary of Minutes of Annual Meeting

The annual meeting of the WERA77 regional committee was held on March 10, 2025. Participants included weed scientists, agronomists, extension specialists, and postdoctoral researchers from land-grant universities across the western United States. The meeting served as a venue for sharing updates on ongoing herbicide resistance research, coordinating collaborative efforts, and planning future activities under the multistate research framework focused on managing invasive and herbicide-resistant weeds in wheat-based cropping systems.

Personnel and Administrative Updates

The meeting opened with administrative updates, including changes in personnel funded through the Pacific Northwest Herbicide Resistance Initiative (PNWHRI). Olivia Landua joined the team in early 2025, though her position was briefly disrupted due to federal funding uncertainty. Efforts to fill new weed science positions in Pendleton and Pullman were partially successful: while the Pendleton position did not result in a hire, two new hires were made in Pullman—one agronomist and one weed scientist. These positions were subsequently frozen due to federal budget cuts, and plans to expand staffing may be postponed until the following fiscal year.

Collaborative Research and Protocol Development

Significant progress was reported on multi-state efforts to develop and validate herbicide resistance screening protocols. Collaborators are working across state lines to standardize the evaluation of weed populations for herbicide resistance. These efforts include greenhouse and field-based studies to ensure consistency in defining resistance thresholds and establishing scientifically sound methodologies. Key challenges discussed included variability in lighting, application carrier volume, and weed growth stage at the time of herbicide application. Olivia Landua led discussions on these technical differences, and the group agreed on follow-up studies to harmonize methods.

Nick Bergmann of Washington State University described ongoing work to involve farmers more directly in the resistance screening process, particularly for sorghum and small grains. Farmer-led sampling and data collection efforts are helping ground the research in practical needs and increasing grower engagement with resistance management strategies.

Technology and Equipment Acquisition

The group reported substantial expansion of regional capabilities through the acquisition of new hardware. More than 30 hammer mills have now been deployed in the Pacific Northwest for harvest weed seed control (HWSC) as a management tactic. Though HWSC shows promise in reducing seed return for key weed species, discussion revealed that 60-80% of weed seeds often escape harvest by shattering prior to combine entry. Efforts are underway to quantify weed species-specific seed retention and develop best management practices for HWSC integration.

Other technological additions include Phenospex sensors for non-destructive measurement of plant growth under different environmental and herbicide stressors, and a range of temperature, light (including UV), and soil moisture sensors to support hydrothermal modeling of weed emergence. Cameras and weather stations have been installed at research sites to track real-time weed emergence and refine predictive emergence models.

State Reports and Research Highlights

Participants presented brief but detailed updates from their respective states:

• Washington: Continued work on integrated weed management (IWM) and chemical rotation strategies. Researchers emphasized the need to manage group 1 and 2 herbicide resistance more effectively and noted legal and safety concerns with certain mechanical weed destruction tools (e.g., weed chippers). A social science collaboration is underway to evaluate grower adoption of resistance strategies and to improve communication between scientists and stakeholders.
• Oregon: Researchers are investing in understanding the role of tillage in weed management, especially as tillage remains unpopular but occasionally practiced. Herbicide resistance screening in Italian ryegrass and downy brome continues, with recent findings identifying EPSP copy number increases as a mechanism of glyphosate resistance. The Willamette Valley is a hotbed for multi-mechanism resistance, especially to groups 1, 2, and 9. Oregon researchers also noted success in expanding herbicide screening in clover and fine fescue systems, and they have recently launched a large-scale survey to assess the impact of the PNW Herbicide Handbook.
• Idaho: Researchers have now completed three years of wild oat collections to assess herbicide resistance, with significant variability in resistance due to dormancy effects. Screening indicates strong resistance to multiple herbicides, including Osprey Extra, Aggressor, and Clethodim. Resistance to Axial is also present but less widespread. Researchers expressed concern over the lack of varietal tolerance screening. Additional screening of lambsquarters, pigweeds, ryegrass, and cheatgrass is underway. Crop rotation trials involving alfalfa are being evaluated for their weed suppression potential.
• Nebraska: Ongoing work on application timing and crop response to Aggressor and Beyond herbicides. Cody Creek, the new chair-elect, will coordinate regional extension publications and research updates moving forward.
• Colorado: Focused on using IWM to “pull cultural levers” that influence weed seed dynamics, especially in wheat/pulse rotations. Researchers are evaluating the potential of winter peas as a viable rotational crop and exploring the interactions between cover crops, soil water dynamics, and weed suppression. Work on glufosinate timing and humidity sensitivity is ongoing.
• Wyoming: Investigating wheat as a cover crop for sugar beet systems. Preliminary data show it is competitive and easy to terminate, though risks include potential wheat streak mosaic virus transmission. Additional research is needed on disease risks and cost-effectiveness.
• Utah: Conducted a baseline survey to determine the geographic extent of kochia resistance. Glyphosate-resistant downy brome was confirmed in southern Utah, alongside other problem species such as Japanese brome. Drone-based image detection technologies are being piloted for forage corn weed control and herbicide application precision.

Emerging Research Themes and Collaboration Opportunities

The committee identified several cross-cutting research themes and collaborative opportunities:

1. Standardizing Greenhouse Screening Protocols: Continued discussions will focus on resolving variability in environmental conditions and application techniques across states.
2. Cover Crop Impacts: A shared research priority is quantifying the biomass and canopy characteristics (e.g., leaf area index) of cover crops and how these influence weed suppression, especially in dryland systems where data gaps remain.
3. Herbicide Use Analysis: Tracy Rauch presented a framework for tracking herbicide use by state and by year using ARM (Agricultural Research Manager) data. The group discussed potential collaborations to link these data with USGS pesticide usage databases, though funding and data access remain challenges.
4. Weed Identification Tools: Extension specialists are interested in developing visual guides and keys to help growers differentiate among problematic annual bromes (e.g., sterile brome, downy brome, ripgut brome, Powell brome), with accompanying management guidelines.

Future Meetings and Symposium Planning

The committee discussed the possibility of organizing a symposium on brome species for the 2026 Western Society of Weed Science (WSWS) meeting. This would provide an opportunity to bring together crop and rangeland researchers to publish findings in peer-reviewed journals such as Weed Science or Weed Technology. A potential speaker from the range science community will be invited to enhance cross-disciplinary engagement.

Summary and Next Steps

The 2025 WERA77 meeting showcased the increasing organizational maturity of the group, particularly in terms of cross-state collaboration, equipment deployment, and interdisciplinary research. Plans for the next year include strengthening regional protocols, continuing to map herbicide-resistant populations, advancing IWM strategies, and expanding extension and outreach activities. The chair-elect, Cody Creek, will lead efforts to compile publications and state updates for the 2025 annual report.

The WERA77 committee made significant progress during the current reporting period toward its stated objectives to address herbicide resistance in wheat-based cropping systems. Through coordinated multi-state research, technology acquisition, collaborative protocol development, and stakeholder engagement, the committee continues to produce tangible outputs and meaningful short-term outcomes that advance integrated weed management (IWM) in the western United States. Below is a summary of accomplishments categorized by outputs, short-term outcomes, activities, and milestones, with clear connections to the objectives laid out in the project proposal.

Objective 1: Continually screen weeds collected from wheat production systems for resistance to commonly used herbicides.

Outputs:

• Standardized herbicide resistance screening protocols have been refined and tested across multiple states, including new recommendations for controlling variables such as weed size, herbicide carrier volume, and environmental conditions in greenhouse assays.
• Extensive datasets of resistance profiles were generated from wild oat, Italian ryegrass, downy brome, and kochia populations across Idaho, Oregon, Utah, and Washington.

Short-Term Outcomes:

• Field-level resistance to commonly used herbicides such as Osprey Extra, Aggressor, Clethodim, and glyphosate was confirmed in several states, directly informing recommendations for chemical rotation and resistance mitigation.
• Glyphosate-resistant downy brome was newly confirmed in southern Utah, and EPSP copy number amplification was identified as a mechanism of resistance in Italian ryegrass populations in Oregon.

Activities:

• State teams conducted both field and greenhouse resistance screenings. Idaho completed its third consecutive year of wild oat collections. Utah initiated a new baseline survey for kochia.
• Teams collaborated to share resistance biotypes and screening data, with Olivia Landua and Albert Adjesiwor leading coordination efforts on methods harmonization.

Milestones:

• Achieved: Develop and deploy a standardized greenhouse screening protocol with cross-state validation by spring 2025.
• In progress: Create a shared repository of biotype resistance data for use in regional management planning (target: fall 2025).

Objective 2: Evaluate integrated approaches for managing common and troublesome weeds in wheat-based cropping systems.

Outputs:

• Over 30 hammer mills were deployed in the PNW to facilitate harvest weed seed control (HWSC) experiments, one of the largest regional testbeds for HWSC in North America.
• Ongoing field trials across Washington, Oregon, and Idaho evaluated the efficacy of reduced tillage, delayed sowing, and herbicide rotations.

Short-Term Outcomes:

• Hammer mills demonstrated potential to intercept up to 30–40% of viable weed seed at harvest. Findings suggest that HWSC may be more effective for species like Italian ryegrass that retain seed longer.
• Integrated use of winter cover crops (e.g., winter peas, wheat as a cover crop) was shown to suppress weeds while maintaining yield potential in dryland systems in Colorado and Wyoming.
• Use of alfalfa in Idaho as a "clean-up" crop in rotations yielded promising results for reducing persistent weed seedbanks.

Activities:

• Field-scale demonstrations were conducted with grower cooperators to test cultural practices, HWSC, and herbicide rotation regimes.
• Camera-equipped weather stations were installed to collect hydrothermal data to refine emergence models and better time IWM interventions.

Milestones:

• Achieved: Regional deployment of hammer mills for HWSC field validation (winter 2024–spring 2025).
• In progress: Finalize IWM field trials assessing interactions between tillage, cover crops, and chemical control (target: 2026 growing season).

Objective 3: Share information on the genetics, biology, ecology, and integrated management of common and troublesome weeds.

Outputs:

• Developed and distributed draft versions of brome species identification guides to help distinguish between sterile brome, ripgut brome, Powell brome, and downy brome, all common in the western U.S.
• Hosted collaborative discussions on weed ecology and genetics, including EPSP gene amplification and dormancy mechanisms in wild oat and brome species.

Short-Term Outcomes:

• Enhanced grower and extension capacity to identify problematic brome species and tailor management to life history traits.
• Provided technical training on herbicide resistance testing and data interpretation to early-career scientists across institutions.

Activities:

• Shared case studies and genetic screening results during the annual meeting and through WSWS presentations.
• Designed a brome-focused symposium for the 2026 WSWS meeting, bridging rangeland and cropland perspectives and integrating weed ecology, genetics, and management.

Milestones:

• Achieved: Launch collaborative weed ID guide initiative and collect input from extension personnel (2025).
• Planned: Publish peer-reviewed synthesis on annual bromes in western systems following the WSWS symposium (target: 2027).

Objective 4: Develop educational outreach/extension programs and disseminate information related to research findings.

Outputs:

• An evaluation survey was disseminated to assess the utility and adoption of the PNW Herbicide Handbook, which continues to be a key reference for regional growers and advisors.
• Field days, grower workshops, and WSWS presentations shared results on HWSC, resistance trends, and IWM strategies.

Short-Term Outcomes:

• Documented grower interest in safer and more effective mechanical weed control technologies, such as updated hammer mill designs.
• Stakeholder feedback led to updates in educational materials, including clarification of resistance mechanisms and best use timing for herbicides.

Activities:

• Active engagement with extension agents, growers, and agribusiness professionals through field visits, on-farm trials, and online presentations.
• Coordinated regional training sessions on weed ID, HWSC implementation, and IWM principles.

Milestones:

• Achieved: Survey stakeholders on usage and satisfaction with PNW Handbook (spring 2025).
• In progress: Develop updated training materials based on survey results and publish new extension factsheets on IWM in dryland wheat (target: fall 2025).

Linkages and Collaborations

WERA77 continued to demonstrate strong internal coordination and external partnerships. Multi-state collaborations enabled shared resources, protocols, and data. Active partnerships were maintained with:

• The Western Society of Weed Science (WSWS) for professional development and dissemination.
• USDA-NIFA-funded programs including CPPM and Western SARE.
• University extension systems and grower networks in seven western states.

New interdisciplinary linkages were also formed between weed scientists and social scientists to evaluate behavioral barriers to adoption of resistance management practices. These partnerships have led to new insights into the grower decision-making process and have informed the design of future outreach programming.

Plans for the Coming Year

In the next year, the committee will focus on completing ongoing greenhouse protocol comparisons and publishing recommendations for standard resistance screening. A collaborative publication on HWSC feasibility and weed seed retention patterns in the PNW will also be initiated. The brome symposium will be finalized, and the committee will continue building tools that support weed identification and management differentiation across species and environments. Emphasis will also be placed on synthesizing ARM data on herbicide use trends and coordinating with federal and state partners to align stewardship goals with regulatory and funding priorities.

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