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Invasive Annuals: Early Detection and Rapid Response

Invasive annual species, such as cheatgrass, pose significant risks to Wyoming lands, and the risks are increasing as new foreign grasses are spreading across the region. These non-native grasses have a negative effect on cattle grazing resources, create a substantial risk of wildfire, and are detrimental to wildlife habitats. A combination of public, private and other organizations are working to eradicate these unwanted grasses by studying them and educating the public on how to control and combat their spread in the region.

The Northeast Wyoming Invasive Grasses Working Group held their annual field tour and educational day on June 18 in Sheridan to highlight the growing concern of medusahead and ventenata, a relatively new invasive species now found in Wyoming and surrounding states. Attended by approximately 200 people, the event provided updates to the research of these invasive grasses and their impact on Wyoming lands. A variety of speakers discussed the impacts to rangeland grazing resources and wildlife habitats. Attendees included landowners, ranchers, ranch managers, students and government employees from various organizations within and outside of Wyoming.

One of the themes stressed during presentations to the participants is early detection and rapid response. Participants were shown detailed pictures of what to look for and various methods now being used to treat areas where these unwelcome grasses have started growing.

Following the presentations, the group loaded up on buses for a hands-on tour of local areas affected by these invasive annual grasses. Tour participants were able to get an up-close look at the grasses currently invading public and private lands to learn how to identify them and assess their unique impacts in the area.

Participants learned these newer invasive species can exclude desirable native species and reduce livestock forage by up to 70%. Additionally, they pose a significant threat to our other natural resources where they can increase wildfire frequency and intensity, endangering wildlife habitats, as well as other public and private lands.

Combating these invasive grasses takes time and resources but controlling and eradicating them is critical to maintaining the natural balance of land resources. Landowners are encouraged to report any suspected invasive grasses to a county Weed and Pest office or through EDDMapS (, a multi-regional resource for reporting, tracking, mapping, identifying and managing weed species.

Landowners should also reach out to agencies such as the NRCS, U.S. Forest Service, U.S. Fish and Wildlife Service or other partner organizations to begin developing a plan to control and eliminate the grasses before they spread further across the state and the country, causing economic harm to ranchers and endangering wildlife habitats and other lands. Your local NRCS field office can help identify what other resources may be available to help.