WERA77: Managing Invasive Weeds in Wheat

(Multistate Research Coordinating Committee and Information Exchange Group)

Status: Active

WERA77: Managing Invasive Weeds in Wheat

Duration: 10/01/2014 to 09/30/2019

Administrative Advisor(s):

NIFA Reps:

Statement of Issues and Justification

Weeds are major pests in wheat-based cropping systems across the United States, with herbicides comprising approximately 85% of the pesticide use and 20 to 30% of input costs for producers. While this chemical control-centered approach to weed management has successfully helped secure income for local communities and provided food sources for billions, dense weed infestations still result in significant losses in crop yield, crop quality, and harvesting efficiency. More recently, the selection and spread of herbicide-resistant weed biotypes, including several species exhibiting multiple-herbicide resistance, further threatens the economic sustainability of the wheat production enterprise.

Among the most difficult to manage grass weeds in wheat-based cropping systems are downy brome (Bromus tectorum), jointed goatgrass (Aegilops cylindrica), feral rye (Secale cereale), ryegrass species (Lolium spp.), cheat (Bromus secalinus), wild oat (Avena fatua), rattail fescue (Vulpia myuros) and ripgut brome (Bromus diandrus). These weeds thrive due to their biological and ecological similarities to wheat and the existence, for several species, of herbicide-resistant biotypes. Furthermore, management decisions, such as 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.

Predominant broadleaf weed species in wheat-based systems include Russian thistle (Salsola tragus), Canada thistle (Cirsium arvensis), kochia (Kochia scoparia), common lambsquarters (Chenopodium album), blue mustard (Chorispora tenella), field pennycress (Thlaspi arvense), prickly lettuce (Lactuca serriola), and wild mustard (Brassica kaber), among others. With available herbicides, producers have been able to control these broadleaf weeds and avoid extensive yield loss. Unfortunately, the recent selection and spread of herbicide resistance, including glyphosate resistance in kochia, is making cost-effective chemically-based control of these broadleaf 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.

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

The goal of 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 weed management in wheat.


  1. Evaluate current and alternative approaches to manage weeds in wheat-based cropping systems with special emphasis in the prevention and management of herbicide resistance.
  2. Coordinate research associated to the development of integrated weed management tactics to reduce the spread and impacts of glyphosate resistance in wheat-based cropping systems.
  3. Share information on the genetics, biology, ecology, and integrated management of herbicide resistance among members of the WERA 077 Multistate Research Coordinating Committee and Information Exchange Group.
  4. Develop and disseminate educational outreach/extension programs 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 regularly 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 into assessing current and alternative programs to reduce the spread an impact of glyphosate and multiple herbicide resistance. Targeted weed biotypes include, but are not limited to, Group 9 (glyphosate) resistant K. scoparia, multiple herbicide resistant A. fatua, and Group 2 (ALS) resistant B. tectorum and S. cereale. 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, participant will present and discuss results of the specific projects conducted at respective states. Examples of the research conducted at different states will include, but are not limited to, 1) integrated management of A. cylindrica, 2) molecular characterization of K. scoparia and A. fatua resistance, and 3) assessment of existing and proposed technologies for weed control and crop safety. The information shared during the meeting will allow the development of improved management strategies with an ultimate goal of 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 decrease the selective pressure and spread of herbicide resistance, (2) coordination of efforts to establish Best Management Practices (BMPs) for problem 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 appropriated, 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.

Expected Outcomes and Impacts

  • Technical bulletins, news releases, and web-based material will provide growers and agricultural professional updated information on integrated approaches to manage weeds, with special emphasis on 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 wheat-based systems.
  • Augmented understanding of the physiological and ecological mechanisms responsible for herbicide resistance will improve growers’ tactics to minimize the spread and impact 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, the WERA 077 Project 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.org) serves as a comprehensive research and education warehouse of information on the ecology and management of this invasive weed. This group has also produced numerous multi-state research articles on the management of weeds in small grain-based systems and developed local education programs on weed problems in wheat.

Future activities will build on the foundation set by the program in past years. Specifically, peer-reviewed research papers will explore: 1) different aspect of the integrated management of agricultural weeds in wheat-based 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 at 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 including 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 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: No standing subcommittees are employed and subcommittees are appointed as necessary by the chair to accomplish specific tasks.

Literature Cited

Avila-Garcia, W. V., E. Sanchez, A.G. Hulting and C. Mallory-Smith. 2012. Target-site mutation associated with glufosinate resistance in Italian ryegrass (Lolium perenne L. ssp. multiflorum) Pest Management Science. 68(9):1248-1254.

Ball, D. A., S. M. Frost, and A. I. Gitelman. 2004. Predicting timing of downy brome (Bromus tectorum) seed production using growing degree-days. Weed Sci. 52:518-524.

DePrado, R., J. Gonzalez-Gutierrez, J. Menendez, J. Gasquez, J. W. Gronwald, and R. Gimenez-Espinosa. 2000. Resistance to acetyl CoA carboxylase-inhibiting herbicides in Lolium multiflorum. Weed Sci. 48:311-318.

Gaines, T., W.B. Henry, P.D. Byrn, P. Westra, S.J. Nissen, and D.L. Shaner. 2008. Jointed Goatgrass (Aegilops cylindrical) by Imidazolinone-Resistant Wheat Hybridization Under Field Conditions. Weed Sci. 56:32-36.

Heap, I. 2004. International survey of herbicide resistant weeds. www.weedscience.org Accessed December 16, 2013.

Hulting, A. G., J. T. Dauer , B. Hinds-Cook, D. Curtis, R. M. Koepke-Hill and C. Mallory-Smith. 2012. Management of Italian ryegrass (Lolium perenne ssp. multiflorum) in western Oregon with preemergence applications of pyroxasulfone in winter wheat. Weed Technol. 26:230-235.

Kniss, A.R., and D.J. Lyon. 2011. Winter wheat response to preplant applications of aminocyclopyrachlor. Weed Technol. 25:51-57.

Kniss, A.R. D.J. Lyon, and S.D. Miller. 2008. Jointed goatgrass management with imazamox-resistant cultivars in a winter wheat-fallow rotation. Crop Sci. 48:2414-2420.

Kniss, A.R., D.J. Lyon, J.D. Vassios, and S.J. Nissen. 2011. MCPA synergizes imazamox control of feral rye (Secale cereale). Weed Technol. 25:303-309.

Kuk Y. I., N. R. Burgos, and R. E. Talbert. 2000. Cross- and multiple resistance of diclofop-resistant Lolium spp. Weed Sci. 48:412-419.

Lehnhoff, E., B. K. Keith, W. E. Dyer, R. K. Peterson, and F. Menalled. 2013. Characterization of multiple herbicide resistance in wild oat (Avena fatua) and its impacts on physiology, germinability, and seed production. Agron. J. 105:854-862.

Lehnhoff, E., B. Keith, W. Dyer, and F. Menalled. 2013. Does multiple herbicide resistance modify crop-weed competitive interactions? Impact of biotic and abiotic stresses on multiple herbicide resistant wild oat (Avena fatua) in competition with wheat (Triticum aestivum). PLoS ONE 8(5): e64478. doi:10.1371/journal.pone.0064478.

Liu, M., A. G. Hulting and C. Mallory-Smith. 2013. Characterization of multiple-herbicide-resistant Italian ryegrass (Lolium perenne L. ssp. multiflorum). Pest Management Science (In Press).

Lyon, D. J., R. N. Klein, and G. A. Wicks. 2002. Rye control in winter wheat. Univ. of Neb. Coop. Ext., NEBGUIDE. G02-1483-A, 1484p.

Mallory-Smith, C., A.G. Hulting, D.Thill, D. Morishita, and J. Krenz. 2007. Herbicide-Resistant Weeds and Their Management. PNW Extension Publication PNW 437.

Miller, S., C. Alford, and W. Stump. 2004. Feral rye - a serious threat to high quality wheat. WY Coop. Ext. Bull 1175, 8 pp.

Park, K. W., C. A. Mallory-Smith, D. A. Ball, and G. W. Mueller-Warrant. 2004. Ecological fitness of acetolactate synthase inhibitor-resistant and susceptible downy brome (Bromus tectorum) biotypes. Weed Sci. 52:768-773.

Quinn, M., D. Morishita, J. Evans, R. Whitesides, and T. White. 2007. Jointed Goatgrass Best Management Practices (BMP) Intermountain Region. Washington State University Extension Bulletin, EB2003. Available at: http://jointedgoatgrass.org

Rainbolt, C., D. A. Ball, D. Thill, J. Yenish. 2004. Management Strategies for Preventing Herbicide-Resistant Grass Weeds in Clearfield Wheat Systems. PNW Extension Publication (PNW 572). p. 8.

Schmale, D., R. Anderson, D. Lyon, and R. Klein. 2008. Jointed goatgrass: best management practices central Great Plains. EB2033. Washington State Univ., Pullman. Available at: http://jointedgoatgrass.org

Stone, A.E. and T.F. Peeper. 2004. Characterizing jointed goatgrass (Aegilops cylindrica) x winter wheat hybrids in Oklahoma. Weed Sci. 52:742-745.

White, A.D., P.W. Stahlman, and F.E. Northam. 2004. Impact of integrated management systems on jointed goatgrass (Aegilops cylindrica) populations. Weed Sci. 52: 1010-1017.

White, A. D., D. J. Lyon, C. Mallory-Smith, C. R. Medlin, and J. P. Yenish. 2006. Feral rye (Secale cereale) in agricultural production systems. Weed Technol. 20:815-823.

Yenish, J. P. and F. L. Young. 2004. Winter wheat competition against jointed goatgrass as influenced by wheat plant height, seeding rate, and seed size. Weed Sci. 52:996-1001.

Young, F. L. and M. E. Thorne. 2004. Weed-species dynamics and management in no-till and reduced-till fallow cropping systems for the semi-arid agricultural region of the Pacific Northwest. Crop Protect. 23:1097-1110.


Land Grant Participating States/Institutions


Non Land Grant Participating States/Institutions

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