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United States Department of Agriculture

Agricultural Research Service

2007 Annual Report

1a.Objectives (from AD-416)
Improve our ability to prevent invasion of rangeland by medusahead, determine the most ecologically sound and cost-effective methods for managing medusahead using herbicides, and develop landscape-scale restoration strategies for medusahead-infested rangeland using successional management.

1b.Approach (from AD-416)
This research will build upon existing efforts to develop ecologically-based invasive weed management strategies. This research will test ecological theories that have potential to become principles that guide invasive plant management and develop those principles into methods for managing weeds. Part of this effort will focus on understanding the key species and grazing strategies that minimize medusahead invasion. Since herbicides are one of the few effective tools for medusahead, this research will attempt to define ecological and economic thresholds for applying them. Finally, the studies will test two novel approaches to restoring medusahead infested rangeland using current ecological theory to guide the implementation. Decision-support tools will be researched and developed to assist land managers in applying existing and new knowledge associated with medusahead in the Great Basin and Columbia Plateau. Replacing 5360-22000-002-00D (5/05)

4a. Grazing guidelines for preventing medusahead invasion. Managers do not have recommendations for properly grazing created wheatgrass under the threat of invasion by medusahead. We discovered that site characteristics were more important than grazing in determining whether or not medusahead invasion occurs. On shallow, clayey soils, fall grazing reduced invasion below that of spring grazing. On larger textured soils, grazing decadent plants can increase their vigor and actually reduce invasion by medusahead. This provides managers with guidelines for grazing crested wheatgrass to help prevent medusahead invasion.

Nation Program 304 Component V:Pest Control Technologies, Problem Statement D:Other Biologically-Based Control and Component X:Weed Management Systems, Problem Statement C:Integrated Weed Management In Noncropland.

4b. Integrated pest management for medusahead. Integrated pest management strategies for managing medusahead do not exist and the invasive weed continues to dominate massive areas across the western U.S. We found that medusahead control increased as imazapic rate increased to 210g ai/ha and herbicide efficacy increased with a pre-application burn. Seeded species established in the study plots, but their response to herbicide rate showed few consistent patterns; some of the seeded species showed little response to herbicide, while others appeared to establish best at different herbicide rates depending on site and whether the plots were burned or unburned. This will allow optimum amounts of herbicides to be applied on medusahead in conjunction with burning and seeding.

Nation Program 304 Component V:Pest Control Technologies, Problem Statement E:Chemical Control, Component VIII:Chemical Control of Weeds, Problem Statement C:Herbicide Efficacy and Application Technology, and Component X:Weed Management Systems, Problem Statement C:Integrated Weed Management In Noncropland.

5.Significant Activities that Support Special Target Populations
These studies may all potentially benefit small farms (including ranching families and holders of grazing allotments on public land) by maintaining the quality and quantity of the forage base, and by increasing the profitability of pasture and hay production.

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings31
Number of newspaper articles and other presentations for non-science audiences7

Review Publications
Sheley, R.L., Laufenberg, S., Jacobs, J., Borkowski, J. 2007. Restoring species richness and diversity in a russian knapweed (Acroptilon repens)-infested riparian plant community using herbicides. Weed Science 55:311-318.

Sheley, R.L., Half, M.L. 2006. Enhancing native forb establishment and persistance using a rich seed mixture. Restoration Ecology 14(4):627-635..

Sheley, R.L. 2007. Revegetating russian knapweed (acroptilon repens)and rabbitbrush (ericameria teretifolia)infested rangeland in a single entry. Weed Science 55:365-370.

Last Modified: 6/2/2015
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