Introduction
Oregon agriculture is highly diverse. The state produces more than 220 commodities that range from crops to livestock (ODA 2024). Field crops play a major role in the state’s agricultural economy, providing substantial economic value and supporting both local and global markets. Major field crops include grass seed crops such as annual ryegrass (Lolium multiflorum Lam.), perennial ryegrass (L. perenne L.), orchardgrass (Dactylis glomerata L.), and tall fescue (Festuca arundinacea Schreb.); and grain crops such as wheat (Triticum aestivum L.), alfalfa (Medicago sativa L.) hay, and other staples. In 2022, grass seed and wheat were among Oregon’s top agricultural commodities, ranking fifth and sixth within the state, with production values of approximately US$639.1 million and US$431.3 million, respectively (ODA 2024). Oregon orchardgrass, fescue, and ryegrass seed represented 94%, 88%, and 84% of U.S. production, respectively, ranking first nationally, while clover (Trifolium spp.) seed crops, including crimson (T. incarnatum L.), white (T. repens L.), and red (T. pratense L.) clovers accounted for 99%, 97%, and 96% of U.S. production, also ranking first (ODA 2024).
Oregon’s field crop production spans diverse climates. Eastern Oregon, where dryland wheat is grown, has wet winters and dry summers, with annual precipitation ranging from 254 to 457 mm, and the driest areas rely on winter wheat-summer fallow systems to conserve soil moisture (Karimi et al. Reference Karimi, Stöckle, Higgins, Nelson and Huggins2017, Reference Karimi, Stöckle, Higgins and Nelson2018). The Willamette Valley in western Oregon has a Mediterranean climate with mild, wet winters and dry summers, and it receives 1,270 to 3,048 mm of precipitation annually (Harr Reference Harr1981; Russell Reference Russell2011). The valley’s fertile soil and temperate conditions support the production of grass and legume seeds, including annual ryegrass; perennial ryegrass; tall fescue; and white, red, and crimson clovers (Oregon State University 2025; Strimbu et al. Reference Strimbu, Mueller-Warrant and Trippe2021), and supply approximately one-third of the global cool-season grass seed market (Durham et al. Reference Durham and Johnson2003).
Weeds pose significant challenges to Oregon field crops by reducing yields and negatively affecting the quality of the final end-use products. For example, winter wheat grain yield in Oregon was reduced by 40% under infestations of downy brome (Bromus tectorum L.) plants at 132 m−2 (Rydrych Reference Rydrych1974). Weed seed contamination can lower the lot purity of grass and legume seeds and disrupts shipments to both domestic and international markets. Alderman et al. (Reference Alderman, Elias and Hulting2011) examined certified fine fescue (Festuca spp.) seed lots submitted to the Oregon State University Seed Laboratory from 1986 to 1995 and 2002 to 2006, and identified 95 different weed seed contaminants. The most frequent were rattail fescue [Vulpia myuros (L.) C.C. Gmel.], annual bluegrass (Poa annua L.), and downy brome, with rattail fescue being the most prevalent, detected in 30% to 61% of samples depending on the year. Similarly, Anderson and Hulting et al. (Reference Anderson and Hulting2013) surveyed 12 clover seed conditioning facilities in western Oregon during the 2013–2014 winter and found that the most common contaminants across clover species were curly dock (Rumex crispus L.), wild mustard (Sinapis arvensis L.), wild radish (Raphanus raphanistrum L.), and small-seeded vetches (Vicia spp.), particularly tiny vetch [V. hirsuta (L.) Gray] and slender vetch [V. tetrasperma (L.) Schreb.]. Weeds also affect specialty crops such as peppermint (Mentha × piperita L.) by diminishing oil quality (Hart et al. Reference Hart, Sullivan, Mellbye, Hulting, Christensen and Gingrich2010). Collectively, these examples highlight the importance of effective weed management to reduce crop competition and protect both yield and product quality.
Surveys of agricultural stakeholders provide valuable insights into perceptions, management challenges, and research needs that influence agronomic decision-making. In other states, such surveys have helped shape policy, informed herbicide resistance programs, and guided integrated weed management research. For example, statewide surveys in Nebraska evaluated weed management challenges and practices (McDonald et al. Reference McDonald, Sarangi, Rees and Jhala2023; Sarangi and Jhala Reference Sarangi and Jhala2018), while a survey in Wisconsin assessed the adoption of cover crops and their effect on weed management in cropping systems of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.], providing important stakeholder perspectives (Chudzik et al. Reference Chudzik, Nunes, Arneson, Arneson, Conley and Werle2024). Despite Oregon’s diverse field crops, no comprehensive statewide survey has been conducted to assess weed management challenges and priorities.
Given the complexity and diversity of field crops and weed species in Oregon, understanding current weed management challenges, and the resource and information needs of stakeholders, is critically necessary for guiding research, extension, and education efforts. To address these needs, a statewide weed management needs assessment survey was conducted among Oregon’s agricultural stakeholders. The survey sought to identify the most problematic weed species, stakeholder resource and information needs, and preferred information delivery methods to prioritize research and outreach in Oregon field crops.
Materials and Methods
The survey targeted agricultural stakeholders involved with the diverse field crops grown in Oregon, including grass and clover grown for seed, mint (Mentha spp.), wheat, and other crops. It was made available online through the Qualtrics platform (https://oregonstate.qualtrics.com/jfe/form/SV_0MJuZY5HuoSC30W) from October 2024 to February 2025. A survey link was distributed via email to people associated with several organizations, including the Oregon commissions for Grass Seed, Clover, and Mint (approximately 800 farms), and other industry groups. Additionally, the survey was shared via social media, including LinkedIn and Twitter, although the precise number of Oregon-based agricultural stakeholders reached is unknown. The survey was also presented using a QR code at the Winter 2025 Oregon State University Extension Seed and Cereal Crop Production meetings, which occurred at three locations with 41, 68, and 95 participants, respectively, and at the Oregon Society of Weed Science meeting, which had 138 attendees. Extension agents also assisted in distributing the survey.
The survey consisted of eight questions divided into three sections: the first gathered respondents’ demographics; the second focused on resource and support needs; and the third addressed current weed management challenges and economic impacts (Table 1). Questions Q1, Q2, Q3, Q4, Q7, and Q8 allowed only one response, with cumulative totals of 100%. In contrast, questions Q5 and Q6 allowed multiple responses, resulting in totals that exceeded 100%. Both Q5 and Q6 included an “others” option, allowing respondents to write in additional weed species that were not included among the predefined choices. The data were exported to a Microsoft Excel file, with responses to each question organized into separate columns, and analyzed and presented visually using bar graphs and pie charts in R statistical software (v.4.4.2; R Core Team Reference Core Team2024). The packages dplyr (Wickham et al. Reference Wickham, François, Henry, Müller and Vaughan2023) and tidyr (Wickham et al. Reference Wickham, Vaughan and Girlich2024) were used for data manipulation, while ggplot2 (Wickham Reference Wickham2016) was employed for data visualization. Not all respondents completed every question in the survey. Surveys were included in the data set only if respondents completed at least 70% of the questions. Therefore, the sample size varied across questions, and analyses were conducted using all available responses for each question. The number of respondents (n) is reported with the results for each question.
Weed management needs assessment survey questions for Oregon field crops.
To evaluate the relationship between respondents’ occupation and their preferences for weed science topics or training, as well as their preferred methods of receiving weed management information, additional analyses were performed focusing on two main stakeholder groups: growers and crop consultants. From an extension standpoint, understanding these preferences is critical for tailoring outreach efforts that effectively meet the needs of each group. Therefore, chi-square (χ2) tests of independence were conducted to assess whether occupation influenced the selection of topics and preferred methods of information delivery (McHugh Reference McHugh2013; Sharpe Reference Sharpe2015). In addition, χ2 tests were used to compare responses from eastern and western Oregon to identify potential regional differences in weed issues and management priorities.
Results and Discussion
Respondents’ Demographics
A total of 184 respondents participated in the survey, including 86 growers, 51 crop consultants, 15 extension agents, and 32 individuals identified as “other” (e.g., researchers, field representatives, and educators). Growers and crop consultants represented 75% of the respondents, the two main stakeholder groups (Figure 1). Seventy-four percent of the respondents were in western Oregon, 26% were based in eastern Oregon. Although county-specific information was not collected, respondents from eastern Oregon represented dryland wheat-producing regions, while respondents from western Oregon represented the Willamette Valley seed production area.
Stakeholder groups among survey respondents in Oregon field crops (n = 184).
Resource and Support Needs
Forty-six percent of respondents expressed the greatest interest in new herbicide technologies (Figure 2). The strong interest underscores the need for a robust herbicide evaluation program to assess both labeled and experimental herbicides for crop safety and weed control efficacy across Oregon’s diverse field crops. In comparison, a statewide survey in Nebraska found that stakeholders prioritized herbicide-resistant weed management (48% of responses), with fewer respondents (23%) specifically noting a need for additional herbicide sites of action or new premix formulations (Sarangi and Jhala Reference Sarangi and Jhala2018). Continuous research and education are a crucial part of promoting best management and stewardship practices while preserving the efficacy and longevity of both new and existing herbicide technologies. Additionally, the interest in herbicide resistance (25%) reflects a growing awareness of resistance issues within the agricultural community, emphasizing the need for targeted research and outreach to help growers manage resistance and minimize its spread. Surveys and herbicide resistance monitoring programs that track and map resistant weed populations can provide valuable insights and alternative management strategies (Bobadilla et al. Reference Bobadilla, Hulting, Berry, Moretti and Mallory-Smith2021; Ribeiro et al. Reference Ribeiro, Mallory-Smith, Brunharo and Barroso2024). Interest in nonchemical weed control methods (17%) and weed biology and ecology (12%) suggest a growing interest in more sustainable weed management practices. Combining biological, cultural, and mechanical methods can help delay resistance evolution and ensure the long-term sustainability of cropping systems (Hatcher and Melander Reference Hatcher and Melander2003; Pannacci et al. Reference Pannacci, Lattanzi and Tei2017). Additionally, understanding weed biology and ecology is essential for optimizing control strategies (Bhowmik Reference Bhowmik1997; Schwartz-Lazaro et al. Reference Schwartz-Lazaro, Gage and Chauhan2021). A χ2 test of independence assessing the relationship between occupation (grower vs. crop consultant) and selected weed science topics indicated no significant association (χ2 = 6.47, df = 3, P = 0.090), suggesting that both groups shared broadly similar interests.
Topics on which respondents in Oregon field crops would like more information or training (n = 161).
Preferred methods for receiving weed management information included field days (36%), followed by workshops (22%), webinars and online courses (21%), and website posts (20%) (Figure 3). The strong preference for field days highlights the value of hands-on learning and direct interaction with experts. Interest in workshops, webinars and online courses, and website posts underscores the need for diverse educational formats to reach a broader audience, particularly those who are unable to attend field days due to time or geographical constraints. The combination of in-person and online methods reflects the growing demand for flexible and accessible learning opportunities. A χ2 test conducted on these preferences also found no significant difference between the two stakeholder groups (χ² = 6.30, df = 3, P = 0.097), indicating comparable preferences for information delivery. While traditional outreach methods remain important, stakeholders seek varied ways to access relevant information. Future outreach efforts should adopt a balanced approach, integrating in-person events like field days with remote learning options such as webinars, online courses, and website posts.
Preferred methods for receiving weed management information in Oregon field crops (n = 163).
Current Weed Management Challenges and Economic Impacts
Survey respondents identified several weed species as being particularly problematic in their fields (Figure 4). Among grass weed species, annual bluegrass (Poa annua L.), Italian ryegrass, and roughstalk bluegrass (P. trivialis L.) were the most frequently reported, with at least 52% of respondents considering them as major concerns, followed by downy brome at 39%. Other problematic grass weeds were reported by less than 15% of respondents (Figure 4). Additionally, 28% of respondents mentioned other grass weed species such as rattail fescue [Vulpia myuros (L.) C.C. Gmel.], barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], foxtail (Setaria spp.), and various bromegrasses (Bromus spp.). A χ2 test of independence indicated a significant association between region (eastern vs. western Oregon) and the grass species reported as being most problematic (χ² = 80.11, df = 6, P < 0.0001). Standardized residuals revealed that annual bluegrass and Italian ryegrass were reported more often than expected in western Oregon, whereas downy brome and jointed goatgrass were reported more frequently in eastern Oregon. Other grass species showed smaller deviations from expected counts. These results are consistent with known regional patterns: annual bluegrass, Italian ryegrass, and roughstalk bluegrass are major weeds in grass seed crops such as annual ryegrass, perennial ryegrass, and tall fescue, and in winter wheat in western Oregon’s Willamette Valley (Bobadilla et al. Reference Bobadilla, Hulting, Berry, Moretti and Mallory-Smith2021; Liu et al. Reference Liu, Hulting and Mallory-Smith2016), while downy brome and jointed goatgrass are a persistent problem in dryland wheat production areas of eastern Oregon (Morrison et al. Reference Morrison, Crémieux and Mallory-Smith2002; Ribeiro et al. Reference Ribeiro, Mallory-Smith, Brunharo and Barroso2024). Downy brome is also a problem in eastern Oregon grass seed crops, including fine fescue (Ball et al. Reference Ball, Frost and Bennett2007; Ribeiro et al. Reference Ribeiro, Brunharo, Mallory-Smith, Walenta and Barroso2023) and Kentucky bluegrass (Poa pratensis L.) (Mallory-Smith et al. Reference Mallory-Smith, Hendrickson and Mueller-Warrant1999; Park and Mallory-Smith Reference Park and Mallory-Smith2004).
The most problematic weed species identified in the survey for Oregon field crops: grass (n = 150) and broadleaf (n = 144).
For broadleaf weeds, wild carrot was by far the most problematic, reported by 65% of respondents. Sharppoint fluvellin [Kickxia elatine (L.) Dumort.] and Russian thistle (Salsola tragus L.) followed, being reported by 37% and 31% of respondents, respectively. Other problematic broadleaf weed species were identified by less than 30% of respondents (Figure 4). Additionally, 30% of respondents listed other problematic broadleaf weeds, including common groundsel (Senecio vulgaris L.), horseweed (Erigeon canadensis L.), thistles (Cirsium spp.), and pigweeds (Amaranthus spp.). A χ² test confirmed significant regional differences in the broadleaf weed species identified as most problematic (χ² = 147.8, df = 7, P < 0.0001). Residual analysis indicated that wild carrot and sharppoint fluvellin were reported more often in western Oregon, whereas kochia and Russian thistle were reported more frequently than expected in eastern Oregon. Other broadleaf species were also reported. Wild carrot, for example, is particularly widespread and difficult to manage in grass seed crops, field edges, and roadside ditches in western Oregon (Cole et al. Reference Cole, Affeldt, Brewster, Colquhoun and Mallory-Smith2005; Colquhoun et al. Reference Colquhoun, Fitzsimmons and Burrill2003; Mueller-Warrant et al. Reference Mueller-Warrant, Whittaker and Young2008). Sharppoint fluvellin is a problematic weed in spring-planted tall fescue in the Willamette Valley of western Oregon (Curtis et al. Reference Curtis, Hinds-Cook, Hulting and Mallory-Smith2010), whereas kochia and Russian thistle are among the most important broadleaf weeds in the dryland wheat-based cropping systems and sugar beet (Beta vulgaris L.) production, respectively, in eastern Oregon (Kumar et al. Reference Kumar, Felix, Morishita and Jha2018; Oreja et al. Reference Oreja, Lyon, Gourlie, Wetzel and Barroso2023).
When asked about their level of concern they have over herbicide-resistant weeds, 58% of respondents reported being very concerned, 39% were somewhat concerned, and only 3% were not concerned (Figure 5). Although species-specific data were not collected, it is noteworthy that most of the problematic species that respondents identified have evolved resistance to some herbicides in Oregon. For instance, Italian ryegrass has evolved resistance to at least seven herbicide modes of action, including inhibitors of acetyl CoA carboxylase (ACCase), acetolactate synthase (ALS), 5-enolpyruvylshikimate-3-phosphate (EPSPS), glutamine synthase, photosystem I, photosystem II (PS II), and very-long-chain fatty acid synthesis (Avila-Garcia and Mallory-Smith Reference Avila-Garcia and Mallory-Smith2011; Avila-Garcia et al. Reference Avila-Garcia, Sanchez-Olguin, Hulting and Mallory-Smith2012; Bobadilla et al. Reference Bobadilla, Hulting, Berry, Moretti and Mallory-Smith2021; Liu et al. Reference Liu, Hulting and Mallory-Smith2016; Perez-Jones et al. Reference Perez-Jones, Park, Colquhoun, Mallory-Smith and Shaner2005; Ribeiro et al. Reference Ribeiro, Berry, Creed, Barroso, Mallory-Smith and Gallagher2025; Stanger and Appleby Reference Stanger and Appleby1989). Similarly, downy brome has evolved resistance to four modes of action, including inhibitors of ACCase, ALS, PS II, and VLCFA synthesis (Ball et al. Reference Ball, Frost and Bennett2007; Mallory-Smith et al. Reference Mallory-Smith, Hendrickson and Mueller-Warrant1999; Park and Mallory-Smith Reference Park and Mallory-Smith2004, Reference Park and Mallory-Smith2005; Park et al. Reference Park, Fandrich and Mallory-Smith2004; Ribeiro et al. Reference Ribeiro, Brunharo, Mallory-Smith, Walenta and Barroso2023, Reference Ribeiro, Mallory-Smith, Brunharo and Barroso2024). Annual bluegrass has evolved resistance to PS II inhibitors and the VLCFA inhibitor ethofumesate (Hanson and Mallory-Smith Reference Hanson and Mallory-Smith2000; Heap Reference Heap2025), while wild oat (Avena fatua L.) populations have evolved resistance to both ACCase inhibitors and the microtubule assembly inhibitor pronamide (Heap Reference Heap2025; Seefeldt et al. Reference Seefeldt, Gealy, Brewster and Fuerst1994). Among broadleaf weeds, ALS-inhibitor resistance has been documented in prickly lettuce (Lactuca serriola L.) (Heap Reference Heap2025). Additionally, Russian thistle and kochia have evolved resistance to ALS inhibitors and to glyphosate, an EPSPS inhibitor (Barroso et al. Reference Barroso, Gourlie, Lutcher, Liu and Mallory-Smith2018; Heap Reference Heap2025; Kumar et al. Reference Kumar, Felix, Morishita and Jha2018).
Overall concern about herbicide-resistant weeds on respondents’ fields in Oregon field crops based on survey responses (n = 149).
In addition to their level of concern about herbicide resistance, respondents were also asked about the average cost of weed control per hectare in their fields. Thirty percent reported an average weed control cost of US$125 to US$250 per hectare, while other respondents reported varying costs across different ranges (Figure 6). The increasing prevalence of herbicide-resistant weeds may be contributing to rising weed control costs. As resistance reduces the efficacy of commonly used herbicides, growers are often forced to implement alternative management strategies that are more labor intensive and costly. In Oregon, for example, growers frequently rely on practices such as spot spraying with backpack sprayers or hand-rogueing to remove weed escapes that survive herbicide applications (Walenta and Spring Reference Walenta and Spring2023). While these methods help prevent further seed production and the spread of resistant weeds, they significantly increase operational costs due to greater labor, time, and resource demands.
Average cost per hectare that respondents report spending on weed control in Oregon field crops (n = 141).
For perspective, these costs are higher than reported in other states and in past surveys. In a 2015 survey in Nebraska, weed management costs in glyphosate-resistant crops were US$90 per hectare for corn and US$81 per hectare for soybean (Sarangi and Jhala Reference Sarangi and Jhala2018). More recent data from a follow-up survey also in Nebraska indicate slightly higher costs, with average weed management in glyphosate-resistant corn and soybean reported at US$101 and US$115 per hectare, respectively (McDonald et al. Reference McDonald, Sarangi, Rees and Jhala2023). The higher costs in Oregon likely reflect both the increasing prevalence of herbicide-resistant weeds and the additional labor and application costs associated with alternative management strategies, including hand removal and spot spraying.
The survey findings highlight current challenges in weed management in Oregon and underscore the need for continued research, education, and outreach. A comprehensive approach that integrates herbicide evaluation, resistance monitoring, and nonchemical weed control strategies will be essential in providing support to stakeholder groups. Additionally, offering a variety of educational opportunities, including field days, workshops, and online resources, will help ensure that stakeholders have access to the latest information and tools they need to improve weed management practices and sustain the long-term productivity of Oregon’s cropping systems.
Practical Implications
The survey results provide timely direction for addressing weed management concerns indicated by Oregon field crop producers. The results indicate that research and control efforts should focus on key problematic species such as annual bluegrass, Italian ryegrass, roughstalk bluegrass, and wild carrot. Widespread concern about herbicide resistance highlights the need to diversify management strategies. Stakeholders also expressed interest in alternative methods and emerging herbicide technologies, indicating a willingness to adopt new solutions. To support these needs, ongoing initiatives such as the Herbicide Evaluation Program, which identifies and tests new herbicides in collaboration with growers, industry partners, and the IR-4 program, and the Herbicide Resistance Monitoring Program, which investigates and tracks the origin and spread of resistance in Oregon, provide critical guidance. In addition, collaboration through the Pacific Northwest Herbicide Resistance Initiative will strengthen regional programs aimed at managing herbicide-resistant weeds across the region. Extension efforts aligned with these programs through hybrid training modules, Oregon State University field days (e.g., the Hyslop Farm Field day in western Oregon and Dryland Field Day in eastern Oregon), and online resources, including the Field Crops Weed Science Webpage, the Weeders of the West Blog posts, social media platforms (LinkedIn and X), can further engage stakeholders and support the adoption of more effective and sustainable weed management practices.
Acknowledgments
We thank the respondents for their time and valuable contributions to understanding the weed management challenges and needs throughout the state.
Funding
This research received no specific grant from any funding agency, commercial or not-for-profit sectors.
Competing Interests
The author declares no competing interests.
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