JACKSON, Wyo. — In the cheatgrass areas treated by Teton County Weed and Pest (TCWP), cheatgrass infestations have successfully been reduced to under three percent area infested.
According to Trevor Bloom, community ecologist with The Nature Conservancy (TNC) in Wyoming, cheatgrass is an invasive species that poses a major threat to wildlife habitat and local communities. Not only is cheatgrass reducing forage quality by outcompeting native plants, the invasive species is also increasing local fire risk by converting the landscape to a flammable grassland.
While cheatgrass is already widespread in Teton County, TCWP Entomologist Mikenna Smith previously told Buckrail that the invasive species is not as out of control here as it is in other parts of the state. Because of this, TCWP Assistant Supervisor Mark Daluge confirms that TCWP is aiming to exhaust the cheatgrass seedbank enough that native plant populations are able to grow back and thrive.
In 2020, 4,400 acres that had cheatgrass infestation averaging around 30 percent of the total vegetation received its first herbicide treatment. Following that initial treatment, Daluge says the infestation was reduced to around three percent of the total vegetation.
“The new areas treated in 2023 should mirror those results, and areas that were treated for the second time should continue to hold to around the three percent mark,” Daluge told Buckrail.
According to Daluge, cheatgrass seeds can be viable for five to six years. However, the 4,400 acres of cheatgrass treated for the second time (out of the 4,700 acres treated this year) should now not be able to germinate even after the residual properties of the herbicide wears off, around 2026.
“We will continue to consult with industry researchers so we can utilize the best science data, and continue to monitor our treatment sites in order to ‘stay ahead’ of the possible reinfestation of cheatgrass,” Daluge says.
TCWP uses indaziflam, also known as Rejuvra, to treat the cheatgrass. TCWP first tested this treatment in a pilot project in 2017 on East Gros Ventre Butte; Daluge says that the project had 27 monitoring transects visited yearly prior to 2020 to evaluate treatment effectiveness compared to the industry standard at the time known as imazapic. According to Daluge, indaziflam notably out-performed imazapic, and since 2020 has replaced imazapic as the industry standard.
Daluge confirms that indaziflam is not known to pose a significant toxicity risk for wildlife; what poses much more of a risk, Daluge notes, is the reduction of available native forage due to persistent cheatgrass infestations.
With regards to community safety, the U.S. Environmental Protection Agency (EPA) categorizes indaziflam as a herbicide with low toxicity effect to humans via oral, dermal and inhalation routes of exposure. Additionally, the EPA says indaziflam is not irritating to the eye or skin and is not a skin sensitizer known to cause a contact allergic reaction. While the EPA has noted that indaziflam can be toxic to mammals, in particular dogs, at doses administered in laboratory studies, concentrations of indaziflam exposed via herbicide applications are deemed “well below concentrations of concern” for those animals.
Still, TCWP has applied herbicide treatments with a 300 foot buffer from any buildings and roadways, and only properties that gave permission received treatment.
In addition to toxicity precautions, TCWP has also been partnering with TNC since 2020 to evaluate the effectiveness of reseeding areas treated with indaziflam to better revegetate native habitat after spraying. Daluge emphasizes that gaining knowledge of the most successful methods to support the local landscape is a primary goal, and adds that TCWP is even considering enhancing seed spread by utilizing their drone.
There is also preliminary research being conducted by the Biotechnology Biocontrol Agency in Italy on biological control as an alternative tool for managing cheatgrass.
