Control of Big Sagebrush (Artemisia tridentata) with Pelleted Tebuthiuron

Ground applications of pelleted tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} at 0.6 kg ai/ha (20% formulation) reduced big sagebrush (Artemisia tridentataNutt. # ARTTR) density by an average of 84 and 92% after 28 months, whereas 1.1 kg/ha killed 94 and 97% of the plants when applied in January or May, respectively. Total standing crop of grasses was unaffected 4 months after tebuthiuron applications. Significant increases in grass production occurred during the second and third growing seasons following tebuthiuron treatment. Desirable forage grasses such as galleta [Hilaria jamesii(Torr.) Benth.], blue grama [Bouteloua gracilis(Wild. ex H.B.K.) Lag. ex Griffiths], and crested wheatgrass [Agropyron cristatum(L.) Gaertn.] generally increased in tebuthiuron-treated plots, whereas sand dropseed [Sporobolus cryptandrus(Torr.) Gray # SPECR] and ring muhly [Mulenbergia torreyii(Kunth.) Hitchc. & Chase] production remained unchanged in comparison with untreated areas.