Nontarget effects of the herbicide tebuthiuron on mycorrhizal fungi in sagebrush semidesert

The effects of the herbicide tebuthiuron (0.36, 0.6, and 1.01 kg/ha in pellet form) on nontarget organisms, vesicular-arbuscular mycorrhizal fungi, were observed in sagebrush semidesert in central Utah. Only the highest level of tebuthiuron application showed any significant effects on mycorrhizal fungi compared to the untreated control. The introduced annual Bromus tectorum L. had both a reduced percent mycorrhizal root infection and reduced spore density in its rhizosphere with the highest herbicide level. The herbicide did not significantly affect mycorrhizal root infection of Sitanion hystrix, a short-lived perennial grass, at any level of application. There was no significant effect of any level of tebuthiuron on germination of mycorrhizal spores collected 6 months after herbicide application.Published with the approval of the Director, Utah Agricultural Experiment Station, as Journal Paper No. 3777