The effect of tebuthiuron on the vegetation of the thorn bushveld of the Northern Cape - a preliminary report.

Abstract

Two formulations of tebuthiuron i.e. Graslan 20P and Graslan 40P are currently being evaluated in the Molopo area. Tebuthiuron was applied aerially at ten application rates, in combination with two application dates. After only two seasons, the chemical has already shown a reasonable selectivity for the woody species. Of these, Acacia mellifera, A. reficiens and Grewia flava are very sensitive while A. erioloba and Dichrostachys cinerea are less sensitive and Boscia albitrunca seems almost resistant to the lower application rates (<1,0 kg a.i./ha). The standing crop of grass on the treated plots increased by between 220 and 740 per cent. Changes in the total grass density and botanical composition can be ascribed to an increased density of Eragrostis lehmanniana. At this stage of the trial, its selectivity in favour of the more desirable woody species, suggest that tebuthiuron shows great promise for controlling bush encroachment in the northern cape, although a final conclusion would only be possible 5 years after its application.

Keywords acacia erioloba; acacia mellifera; acacia reficiens; boscia albitrunca; botanical composition; bush control; bush encroachment; dichrostachys cinerea; eragrostis lehmanniana; grass density; grass production; grasses; grewia flava; northern cape; selectivity; south africa; standing crop; tebuthiuron; woody species

Journal of the Grassland Society of Southern Africa.