Countywide Cooperative Weed Management Area in Idaho’s Lemhi County Solidifies Weed Program

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Rural lifestyles and agricultural roots run deep in Salmon, Idaho and throughout Lemhi County. Encompassing about 3 million acres, Lemhi County is home to miles of backcountry roads and trails, the Salmon River, and part of the Frank Church-River of No Return Wilderness (Sidebar).

About 90% of the county is federally owned with 71% managed by United States Forest Service (USFS) and 20% by the Bureau of Land Management (BLM). Rangeland and wildland resources on these public lands are important for livestock production, wildlife habitat and recreation. “Less than 8% of our county is under private ownership, so it was important to develop strong partnerships with our federal agencies to protect these lands from invasive plants and effectively manage infestations in Lemhi County,” says Shannon Williams, Extension Educator for Lemhi County.

The Lemhi County Cooperative Weed Management Area (CWMA) was formed in 1998 by the Salmon District BLM and the Salmon-Challis National Forest in cooperation with Lemhi County Cooperative Extension Service. The Lemhi CWMA encompasses the bulk of the county with the exception of the Frank Church-River of No Return Wilderness, which lies within a different CWMA. A strategic plan was ratified by participating agencies in 2001.

Williams helped formalize the partnership and explained there were three landmark events that came together to help launch the Lemhi CWMA and increase program effectiveness and capabilities. “The first important event was the availability of federal funding through Idaho State Department of Agriculture to support operating expenses and weed management programs for CWMAs. The second was developing and signing participating agreements with the Salmon District BLM and Salmon-Challis National Forest, which provided multi-year funds for weed management projects. The third positive event was hiring the first dedicated, full-time county weed superintendent in Lemhi County.”

“The mission of the Lemhi CWMA is to bring together all land owners (private, federal and state) who have responsibilities to control weeds within the boundaries of the Lemhi CWMA to develop common weed management goals,” explains Daniel Bertram. Bertram is the weed superintendent for Lemhi County and a core member of the CWMA steering committee. The financial resources provided by the CWMA partnership and strong support from Lemhi County funds the weed superintendent position and a permanent technician to supervise seasonal work crews and serve as the database manager for the CWMA.

“The participating agreements we have with agencies through the Lemhi CWMA are important for consolidating funding,” says Bertram. Participating agreements are approved for five years, which allows for program consistency. Agency funding for invasive plant management following fires, and other county, state, and federal funding for weed control goes directly to the Lemhi CWMA and can be allocated over time to more efficiently utilize dollars where and when they are needed. The Resource Advisory Committee (RAC) has been a key partner in providing funding to the CWMA for invasive plant management on private and federal lands on the Salmon River corridor. A steering committee composed of federal, state, and county natural resource managers, private landowners and agricultural and industry representatives work together to prioritize weed species and areas for treatment regardless of land ownership.

“One thing that makes Lemhi CWMA so unique is that all our invasive plant activities are done with inter-agency cooperation,” explains Diane Schuldt, wildlife biologist and noxious weed program coordinator for the Salmon-Challis National Forest. “The CWMA blurs ownership boundaries in Lemhi County and there are no territorial issues between agencies,” says Schuldt. “Another key to our success is that many of us on the steering committee have been involved with the program since its inception. We share the workload, share resources, and have same goals and objectives for our program.”  To provide additional support to the program, the USFS houses and manages the weed inventory and monitoring data for the CWMA.

A high priority project currently underway for the CWMA is to consolidate agency equipment and supplies used for weed management under one facility to more efficiently share resources. This facility would include a wash station for field vehicles, storage for herbicides and other supplies and equipment, and provide office space for seasonal employees working on invasive plant management. Lemhi County provided the land for the facility, and the CWMA steering committee is working on funding sources for construction. “Right now we have equipment and resources scattered throughout the county and it would be much more efficient and help coordination to house everything at one location,” says Bertram. “This would really help reduce our operating costs and make it easier for us to work together.”

The BLM, another key partner in the CWMA, contracts their on-ground weed control with Lemhi County. “This reduces the need for BLM to have extra vehicles, herbicide application equipment and seasonal employees,” explained Chris Tambe, weed coordinator for BLM. Lemhi County weed program employees work on both private and federal lands and have a government-issued driver license that allows them to operate government equipment. County employees also go through federal training to safely operate off-road vehicles. “It’s easier for the county to hire employees on a temporary basis,” says Tambe, “and we work hand-in-hand with Lemhi County to train new employees by having them work with experienced applicators. This is a win-win situation for everyone since it cuts down on duplication of equipment and resources and allows us to use our dollars more efficiently.”


Controlling rush skeletonweed as part of the Continental Divide Barrier Zone Project in Lemhi County.

Lemhi County CWMA endorses an integrated approach to managing invasive plants including prevention, public education, inventory, monitoring, and on-ground management. Early detection and control of newly invading weeds into the county is a priority for the Lemhi CWMA. The rush skeletonweed eradication program is one example that highlights the importance of partnerships. Located in a remote backcountry area about a mile from an access road, rush skeletonweed infests both BLM and USFS lands. Implementing on-ground control was challenging, but as part of the cooperative program, the BLM worked with the USFS to aerially supply tanks of water and application equipment to the treatment site. This gives county weed district and USFS weed crews a ready source of supplies to treat infestations on federal lands. The site is monitored twice during the growing season and rush skeletonweed plants controlled. Since Milestone® has not been approved for use on BLM land, Tordon® 22K at 1 quart/A plus 1 pint/A 2,4-D is applied at late bolt to flower growth stage and providing good results. “The problem we are finding on this site is that we are getting about 30 new infestations each year from seed blowing in from large populations located south and west of our county,” explained Bertram. “We still hope to contain the infestation and prevent movement into non-infested sites and across the border to Montana to support efforts of the Continental Divide Rush Skeletonweed Project.” 

Student and 4-H volunteers work together to established spotted knapweed biocontrol insectary.

Spotted knapweed is the most problematic and widespread weed in Lemhi County infesting about 65,500 acres within the CWMA. “The county treats about 1,000 acres of spotted knapweed each year and is getting excellent control with Milestone at 5 to 7 fluid ounces per acre (oz/A) or ForeFront® R&P at 2.6 pints per acre [GrazonNext® HL at 2.1 pints per acre],” says Bertram. Milestone is applied rosette to bolt growth stage or in fall and ForeFront R&P is applied when spotted knapweed is flowering to help stop viable seed production. Herbicide treatments are combined with biological control agents on larger infestations to help reduce knapweed spread. In 2010, local high school students and 4-H groups with the help of the environmental science teacher and USFS weed crews built a spotted knapweed biological control insectary. The insectary will be used as a source for biological control agents on spotted knapweed within the Lemhi CWMA and for educating students and others in the community about biological control of invasive plants.

The strength of the partnership in Lemhi CWMA is evident among its members. Each agency is quick to discuss the strengths, level of support, and commitment of the other agencies. The partners agree that, “our goal is to prevent the introduction, reproduction and spread of designated noxious weeds and invasive exotic plants into and within the entire CWMA. The only way to efficiently manage invasive plants and stretch limited resources is by working together. You can have excellent management tools, but they aren’t effective unless all the partners work toward a common goal in a planned and coordinated program.” 

Pictured left to right, three of several Lemhi CWMA partners Shannon Williams, Daniel Bertram, and Diane Schuldt.


A risk assessment for Milestone and four other herbicides by the BLM should be completed this summer. The supplemental NEPA document will be needed following completion of the risk assessments. The NEPA documents should be completed the winter of 2012. Pending completion of the necessary documents and funding, the use of aminopyralid (Milestone) and its tank and premixes will be available for use in fall of 2012on BLM lands.

Published 2011; trademark updated June 2019.

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Milestone and GrazonNext HL are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details. State restrictions on the sale and use of Milestone apply. Consult the label before purchase or use for full details. Tordon 22K is a federal Restricted Use Product.  Always read and follow label directions.©2019 Corteva