WERA77: Managing Invasive Weeds in Wheat

(Multistate Research Coordinating Committee and Information Exchange Group)

Status: Active

WERA77: Managing Invasive Weeds in Wheat

Duration: 10/01/2019 to 09/30/2024

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Due to ease and efficiency, a herbicide-based approach to weed management has successfully helped secure income for local communities and provided food sources for billions of people. However, these systems also have selected herbicide-resistant (HR) weed bioytpes. Globally, 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. 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.

Among the most difficult to manage herbicide resistant 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). 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). Recently, three downy brome biotypes resistant to EPSP synthase have been documented in fallow fields in Washington state. Multiple resistant Italian ryegrass, resistant to ALS and ACCase herbicides, also has been documented. Furthermore, management decisions, such as wheat only cropping systems, the use of semi-dwarf wheat cultivars, and broadcast applications of fertilizer have resulted in a steady increase in the densities of some of these species.

Herbicide resistance in downy brome and Italian ryegrass are making cost-effective chemically-based control of these weeds extremely difficult. As a result, farmers across the region are turning to mechanically-based 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 a herbicide site of action is still effective, these products are used heavily, further increasing the selection pressure for resistant biotypes.

A comprehensive understanding of the environmental, genetic, and management factors conditioning the abundance and spread of downy brome, feral rye, jointed goatgrass and Italian ryegrass grass 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 herbicide resistant downy brome, feral rye, jointed goatgrass, and Italian ryegrass in wheat.


  1. Evaluate the integration of chemical, cultural, and mechanical approaches to manage downy brome, feral rye, jointed goatgrass, and Italian ryegrass in wheat-based cropping systems with special emphasis in the prevention and long-term management of herbicide resistant biotypes.
  2. Coordinate research to develop integrated weed management practices to reduce the spread and impacts of ALS, ACCase, LCFAI, and EPSP synthase resistant downy brome and Italian ryegrass in wheat-based cropping systems.
  3. Share information on the genetics, biology, ecology, and integrated management of downy brome, feral rye, jointed goatgrass, and Italian ryegrass, including herbicide resistant and herbicide susceptible biotypes, among members of the WERA 077 Multistate Research Coordinating Committee and Information Exchange Group.
  4. Develop educational outreach/extension programs and disseminate information related to research findings on the integrated management of grass and broadleaf weeds in wheat-based cropping systems, targeting producers, crop consultants, grain merchandisers, grain processors, extension personnel, and other scientists.

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 integration of mechanical, chemical, biological, and cultural management technologies for controlling 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 ALS, ACCase, LCFAI, and EPSP synthase resistant downy brome and Italian ryegrass. Research will involve molecular, physiological, and ecological characterization of herbicide resistance, weed seedbank dynamics, and mechanisms driving crop-weed competitive interactions.

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 of downy brome, feral rye, jointed goatgrass and Italian ryegrass  2) molecular characterization of herbicide resistance, 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 with an ultimate goal of utilizing 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 herbicide resistant 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 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 committee.

Expected Outcomes and Impacts

  • Technical bulletins, news releases, and web-based material will provide growers and agricultural professionals with updated information on integrated approaches to manage weeds, with a special emphasis on management of herbicide resistant biotypes.
  • Educational outreach programs on the integrated management of grass and broadleaf weeds in wheat-based cropping systems will allow growers and agricultural professionals to develop economical and sustainable weed management programs in these cropping systems.
  • An augmented understanding of the physiological and ecological mechanisms responsible for herbicide resistance will improve growers’ tactics to minimize the spread and impact of resistant biotypes.
  • Increased knowledge of the ecological and societal factors conditioning the success of integrated weed management programs will be reflected in the publication of peer reviewed journal articles, extension publications, and accessible databases.

Projected Participation

View Appendix E: Participation

Educational Plan

Since its creation in January 2009, the WERA 077 Project and previous similar projects (WRC77, WRCC77, and WCC77) has been associated with several collaborative research and outreach activities. Examples include the development and implementation of the National Jointed Goatgrass Research Program. The program’s website (www.jointedgoatgrass.wsu.edu) serves as a comprehensive research and education warehouse of information on the ecology and management of this invasive weed. This group continues to produce numerous multi-state research articles on the management of weeds in small grain-based systems and develop local educational programs on weed problems in wheat.

Future activities will build on the foundation set by the program over the past 10 years. Specifically, peer-reviewed research papers will explore: 1) different aspects of integrated management of downy brome, feral rye, jointed goatgrass, and Italian ryegrass in wheat-based cropping systems and 2) approaches to decrease the selective pressure and spread of herbicide resistance in the Great Plains, Intermountain states, and Pacific Northwest. Additionally, research findings will be presented and published in research reports, proceedings of regional and national weed science societies, or as a thesis or dissertation.

The information gathered will be used to educate farmers and agricultural professionals on BMPs in wheat. Dissemination of extension-outreach material will be conducted in each state to allow individuals to enhance their current weed management programs. Our educational activities will include online information databases, informational meetings, extension publications, field tours, popular press articles, and other media sources, such as the eXtension website (about.extension.org).


Chair: 1. Maintain a liaison with the Administrative Advisor, CSREES Advisor, and other organizations with related interests. 2. Arrange for the annual meeting (room, overhead/slide projector, etc.) at a site chosen by the membership. 3. Solicit items of business, prepare agenda, and preside at the annual meeting. 4. 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 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 are employed.

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USDA-ARS Beltsville Agricultural Resarch Center
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