EVALUATION OF TEBUTHIURON AS A SELECTIVE HERBICIDE FOR CONTROL OF MOUNTAIN BIG SAGEBRUSH, WYOMING BIG SAGEBRUSH, BASIN BIG SAGEBRUSH AND SILVER SAGEBRUSH

The purposes of this study were to determine: (1) the feasibility of tebuthiuron as a selective herbicide for the control of sagebrush species, (2) rates of application needed for selective sagebrush control on rangeland, and (3) the effects of the chemical treatment upon associated vegetation and subsequent forage production.;Cool season grasses were sensitive to tebuthiuron. Prairie junegrass had live canopy and live basal cover reductions with tebuthiuron applications of 0.5 lb ai/A and above. The same reductions were found in Western wheatgrass when application rates were 0.75 lb ai/A and above. Needleandthread and green needlegrass were not significantly damaged with rates up to 1.0 lb ai/A. Blue grama, a warm season grass, was resistant to any damage from rates up to 1.0 lb ai/A. Since tebuthiuron appears to be ineffective in controlling downy brome, pricklypear cactus and broom snakeweed, careful management is required to prevent these undesirable species from occupying bare areas once inhabited by the sagebrush. Good range management practices should result in eventual increased production of desirable perennial grasses.;Further research and a longterm study on the product is needed to determine how long sagebrush will be controlled with tebuthiuron, the length of time required for a range to reach species equilibrium, what total species changes take place on the range after application of the herbicide, cost effectiveness of the chemical and comparisons of tebuthiuron with other chemical treatments.;The study indicated that basin big sagebrush, mountain big sagebrush and Wyoming big sagebrush could be effectively controlled with tebuthiuron applied in either spring or fall at rates between 0.5 lb ai/A and 1 lb ai/A. It was not an effective treatment on silver sagebrush.