Herbicides for the control of grass weeds in pastures of Townsville stylo (Stylosanthes humilis)

Abstract

The use of herbicides to control annual grasses in pastures of Townsville stylo (Stylosanthes humilis) was studied at Katherine, N.T. The herbicides chlorthal, trifluralin, benefin, sindone B, and siduron all controlled the annual grasses Digitaria adscendens and Brachiaria ramosa. The outstanding herbicide was chlorthal, which at 6 lb a.i. an acre pre-emergence gave a Townsville stylo dry matter yield of 3250 lb an acre compared with 1130 lb an acre for the unweeded control and 2440 lb an acre for the handweeded control. At maturity there was no grass in the chlorthal plots and 1940 lb an acre in the unweeded control plots. The data suggest that, without defoliation during the growing period, total suppression of Townsville stylo can be expected when the grass population at establishment exceeds 37 per cent of the total plant population.