Cheatgrass control with herbicides to improve seeding success: renewed Interest on Rangelands

Authors: Clements, Darin - Charlie; YOUNG, JAMES - Retired ARS Employee; Harmon, Daniel - Dan

Submitted to: The Progressive Rancher
Publication Type: Popular Publication
Publication Acceptance Date: 3/21/2024
Publication Date: 4/10/2024
Citation: Clements, D.D., Young, J.A., Harmon, D.N. 2024. Cheatgrass control with herbicides to improve seeding success: renewed Interest on Rangelands. The Progressive Rancher. 24(4):26-28.

Interpretive Summary:

Technical Abstract: Public land management agencies did not drop the use of herbicides in the late 1970s because they were afraid of the environmental consequences, they dropped them because they were afraid of the comments from the highly vocal general public. Congress stopped appropriating funds for the improvement of publicly owned rangelands to avoid criticism from environmental groups. It took a good two decades to reinvigorate the need for herbicidal weed control research to add to the toolbox of range improvement practices needed to combat cheatgrass-infested rangelands. This rallying cry was loud and clear as resource managers screamed from the mountain tops that they needed a method for controlling cheatgrass on rangelands so that they could seed perennial grasses to suppress cheatgrass and wildfires. There were still individuals in the management agencies that remembered the early research of Dick Eckert, Ray Evans and James Young of the Great Basin Rangelands Research Unit based out of Reno, Nevada on the use of herbicides to control cheatgrass and seeding rangelands to perennial grasses. It was quickly recognized that as time had passed, the patents on the herbicides they were researching had run out, and the cost of renewing the registration of those herbicides was not of interest to the companies that had originally developed them. This renewed interest in research of herbicides to control cheatgrass resulted in the development and release of chemicals such as sulfometuron-methyl, commonly known as OUST, imazapic (Plateau), sulfometuron-methyl chlorosulfuron (Landmark) and indaziflam (Rejuvra). Sulfometuron-methyl was mis-applied on erodible soils in southeastern Idaho and was removed from rangeland use do to this catastrophe. Imazapic is the most commonly used soil-active pre-emergent herbicide on Intermountain West rangelands and has proven to be quite successful by controlling cheatgrass at levels of 95-98%. The repackaging of sulfometuron-methyl with chlorosulfuron proved to be quite successful by controlling cheatgrass at levels of 96-99% while at the same time improving the control of broadleaf weeds, but when the chemical company sold out, the patent for sulfometuron-methyl chlorosulfuron was not accomplished and the product went out of production. A more recent soil-active pre-emergent herbicide, indaziflam is gaining popularity on controlling cheatgrass-infested rangelands, but this herbicide has a much longer residue activity up to 3-years. The application of indaziflam on habitats with good residual perennial grass densities has proven to be very effective at reducing cheatgrass and associated weeds, while at the same time improving perennial grass stand vigor, reducing the chance, rate, spread and season of wildfires and improving forage quality. The importance of developing effective control methods on cheatgrass-infested habitats continues to be a high priority to improve seeding of perennial grasses to suppress cheatgrass and wildfires.