Duration: 10/01/2024 to 09/30/2029

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Production of most field crops has become heavily reliant on herbicides, and long-term overreliance on herbicides as the main weed management tool has resulted in a continuous increase in the evolution of herbicide-resistant (HR) weed populations. Globally, over 500 unique cases (species x site of action) of HR weeds have been documented. Many of these weeds also occur in wheat fields in the United States. As a result, dense weed infestations result in significant losses in crop yield, crop quality, and harvesting efficiency. Estimates from North America have shown that if weeds are left uncontrolled, a potential yield loss of 26% in winter wheat and 33% in spring wheat could occur which translates into billions of dollars in lost value. HR weed populations also negatively affect weed managers, complicating their day-to-day decisions and often reducing their bottom line. For example, winter annual grass weeds in wheat affect wheat well beyond in-season competition for resources. Once grain reaches an elevator, weed seeds contribute to dockage or foreign material, affecting the cash price for the producer and the marketability and end-use quality of their crop. To maintain the economic sustainability of wheat production systems, long-term, effective integrated weed management plans must be developed and shared.

Statement of Issues and Justification

Among the most difficult to manage HR grass weeds in wheat-based cropping systems are Bromus tectorum (downy brome), Secale cereale (feral rye), Aegilops cylindrica (Jointed goatgrass), and Lolium perenne spp. multiflorum (Italian ryegrass), and wild oat (Avena fatua). These weeds thrive due to their biological and ecological similarities to wheat and the existence of biotypes that are resistant to acetolactate synthase inhibiting (ALS), acetyl CoA carboxylase (ACCase), long chain fatty acid inhibiting (LCFAI) herbicides, and glyphosate resistance (EPSP synthase). Broadleaf such as kochia (Bassia scoparia), Russian thistle (Salsola tragus), prickly lettuce (Lactuca serriola), mayweed chamomile (Anthemis cotula) are also present in the region and can be difficult to control in wheat-based cropping systems due to the presence of biotypes resistant to ALS, EPSP synthase, and auxin mimics. There are biotypes of these grassy and broadleaf weeds with resistance to multiple herbicide sites of action. Furthermore, management decisions, such as wheat-only or wheat-barley cropping systems, broadcast applications of fertilizer, planting seeds contaminated with weed seeds, movement of weed seeds by farm equipment, etc., have resulted in a steady increase in the densities of some of these weed species.

Farmers across the region are turning to tillage for weed control, an approach that could result in increased soil erosion and a loss of stored soil water, particularly in areas with easily eroded soils and limited precipitation. Additionally, in instances where an herbicide site of action is still effective, these products are used heavily, further increasing the selection pressure for resistant biotypes. While herbicides will undoubtedly remain an important weed management tool in wheat-based cropping systems well into the future, even the most ardent supporters of herbicides acknowledge the necessity of reducing reliance on herbicides through integrated weed management practices.

A comprehensive understanding of the environmental, genetic, ecological, and management factors conditioning the abundance and spread of troublesome grassy and broadleaf weeds in wheat-based cropping systems is a required step to develop best management practices to reduce their presence and impact. In this context, sharing research efforts and information, coordinating extension activities, and jointly developing integrated weed management strategies will improve our understanding of weeds and their management. Ultimately, this regional knowledge will facilitate the rapid transmission of new information to wheat growers across the western U.S.

The goal of the WERA 077 Multistate Research Coordinating Committee and Information Exchange Group is to develop a networking structure among scientists to ensure that wheat producers have access to the most accurate, non-biased information possible for economical and sustainable management of HR and troublesome weeds in wheat.

Objectives

Procedures and Activities

The WERA 077 Multistate Research Coordinating Committee and Information Exchange Group will meet annually to discuss and develop science-based information regarding the discovery, development, and integrated management of weeds in wheat-based cropping systems. Special emphasis will be allocated to assessing current and alternative weed management programs to reduce the spread and impact of herbicide-resistant weeds in the region. Research will involve molecular, physiological, and ecological characterization of herbicide resistance, weed seedbank dynamics, and mechanisms driving crop-weed competitive interactions. There will also be an evaluation of new technologies and practices such as harvest weed seed control (HWSC).

The knowledge generated in Objectives 1 and 2 will be shared among members of the WERA 077 Committee (Objective 3). To maximize participation of members of the Committee, we will coordinate our meeting with the Western Society of Weed Science annual conference. During the meeting, participants will present and discuss results of the specific projects conducted in their respective states. Examples of the research conducted in different states will include, but are not limited to, 1) integrated management downy brome, feral rye, jointed goatgrass, Italian ryegrass, wild oat, kochia, Russian thistle 2) discovery and characterization of existing or new HR weed biotypes, 3) understating the seed biology, genetic and phenotypic variation among resistant and susceptible populations, and 4) assessment of existing and proposed technologies for weed control and crop safety. The information shared during the meeting will allow for the development of improved management strategies to utilize more diversified approaches for wheat-based cropping systems while reducing the economic impact of invasive weeds on wheat growers.

To improve the efficacy of weed strategies in wheat-based cropping systems, we will develop and disseminate educational outreach/extension programs (Objective 4). This information will be disseminated among producers, crop consultants, grain merchandisers, grain processors, extension personnel, and other scientists. Examples of coordinated outreach/extension efforts include: 1) development of educational materials including fact sheets, technical bulletins, and news releases to manage HR weeds and decrease the selective pressure and spread of herbicide resistance, 2) coordination of efforts to establish Best Management Practices (BMPs) for these problematic weed species that incorporate economic and herbicide resistance management components, 3) organization of field days and Ag professional meetings, 4) web-publication of results, and 5) when appropriate, dissemination through webinars and other distant learning approaches. Collectively, this information will allow growers to understand approaches to develop integrated weed management practices tailored to the specifics of their cropping systems. Additionally, the information gathered by members of the WERA 077 Committee will be disseminated within the scientific community through the publication of peer-reviewed journal articles and presentations at regional and national professional meetings. Lastly, data collected will be used to support funding efforts that align with the committee’s objectives.

Expected Outcomes and Impacts

Projected Participation

View Appendix E: Participation

Educational Plan

Organization/Governance

Chair:

• Maintain a liaison with the Administrative Advisor, CSREES Advisor, and other organizations with related interests.


• Arrange for the annual meeting (room, overhead/slide projector, etc.) at a site chosen by the membership.


• Solicit items of business, prepare agenda, and preside at the annual meeting.


• Appoint subcommittees as necessary to carry out WERA 077 business.

Recording Secretary:

Record and submit minutes of the annual meeting to the Administrative Advisor and member participants. To provide continuity in leadership, the recording secretary becomes the chair and a new individual is elected to serve as recording secretary.

Subcommittees:

Appointed as necessary by the chair to accomplish specific tasks; no standing subcommittees would be established.

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Attachments

Land Grant Participating States/Institutions

NE, OR, UT, WA

Non Land Grant Participating States/Institutions