Herbaceous Vegetation Changes following Applications of Tebuthiuron for Brush Control

Abstract

Aerial applications of 2.24 kg/ha (active ingredient) of tebuthiuron pellets to mixed brush and whitebrush-dominated stands in South Texas significantly increased grass standing crops at 1, 2, and 3 years after treatment. Higher rates did not significantly increase grass standing crop over that resulting from 2.24 kg/ha; lower rates did not increase grass standing crop compared to that on untreated plots at two of three locations. The genus Chloris appears to be particularly tolerant of the herbicide, and by 2 to 3 years after application, the overall grazing value of the grass stand was improved where at least 2.24 kg/ha of tebuthiuron were applied. Forb production and diversity were decreased where 1 kg/ha or more of the herbicide was applied, and the detrimental effect on forbs increased with increasing application rate. Forb production was nearly eliminated for 2 years following application of 4.48 kg/ha of tebuthiuron but recovery of the population was evident after 3 years regardless of rate of application.