Cheatgrass control with herbicides to improve seeding success: the development years

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

Submitted to: The Progressive Rancher
Publication Type: Popular Publication
Publication Acceptance Date: 2/21/2024
Publication Date: 3/5/2024
Citation: Clements, D.D., Young, J.A., Harmon, D.N. 2024. Cheatgrass control with herbicides to improve seeding success: the development years. The Progressive Rancher. 24(3):32-34.

Interpretive Summary:

Technical Abstract: Weed control has been a concern of farmers since agriculture began. The use of herbicides to control weeds only came into wide use in the first half of the twentieth century. The first half of the twentieth century produced new herbicides and new methods of administering them. Scientists tested a variety of compounds and formulations to test on the control of various plants and plant types, and some of this testing was quite extreme. The real big breakthrough in herbicide development occurred in the 1930s when the phenoxy compound that regulates plant growth was discovered. This discovery resulted in the development of the very popular 2,4-D (2,4-dichlorophenoxy acetic acid), which initiated a revolution in chemical weed control. The characteristic that made 2,4-D unique as an herbicide was its’ physiological selectivity; it acted only on broadleaf plants. Therefore, it could be applied on cereal grain crops (grasses) without harming them, yet selectively killing the competing broadleaf weeds. Similarly, it could be applied to excessively dense stands of big sagebrush to release the remnant stands of perennial grasses. Early researchers, however, faced the challenges of using herbicides to kill cheatgrass, while not injuring the perennial grasses needed to suppress cheatgrass. Pioneer researchers, Ray Evans and Richard Eckert, with the USDA-Agricultural Research Service, Great Basin Rangelands Research Unit were tasked with the application of numerous herbicides to control cheatgrass, while at the same time increasing perennial grasses. From 1958 through 1966, Evans and Eckert conducted research trials using eighteen different soil active herbicides at seven separate locations in Nevada and northeastern California. One of the soil active herbicides that Evans and Eckert identified as a good candidate was atrazine. They summarized their findings as “activity of atrazine was long enough for consistent season long control of downy brome (cheatgrass) under conditions that existed on all years of the study. Atrazine also controlled a wide spectrum of weeds found in these experiments.” All requirements for registration of atrazine for herbicidal fallows on rangelands were met or exceeded. Within the natural constraints of the Great Basin environment for perennial grass seedling establishment, grasshopper infestations, droughts, trespass cattle and Mormon cricket outbreaks, the atrazine fallow was an unqualified success for seeding for big sagebrush/bunchgrass communities converted to cheatgrass dominance. Due to increased environmental concerns, Congress stopped appropriating funds for the improvement of publicly owned rangelands to avoid criticism from environmental groups. The private ranching sector should have welcomed the new technology as a means of converting their own rangelands from cheatgrass dominated to perennial grass dominated rangelands to provide dependable forage as well as reduce wildfire risks associated with cheatgrass. Public land management agencies responded to the new national environmental review regulations, not with compliance, but by trying to avoid them. Coupled with reduced funding for range improvement practices, this policy replaced range improvement practices with grazing management. 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.