Herbicides for weed control in grain sorghum crops in the Northern Territory

Abstract

In experiments conducted in the 1968-69 wet season at the Katherine Research Station, Northern Territory, a number of herbicides gave good control of the grass weed Pennisetum polystachyon in grain sorghum crops. Linuron at 3 lb a.i. an acre and PCP at 20 lb a.i. an acre as pre-emergence applications effectively controlled grasses with no apparent adverse affects on the crop. With both there were significantly higher grain yields than on unweeded control plots containing an average of 1378 lb dry weight of P. polystachyon an acre. Fluometuron at 3 lb a.i. an acre late pre-emergence and early post-emergence and chlorthal at 7 lb a.i. an acre pre-emergence controlled grasses but did not increase grain yields. Further investigations are warranted with these herbicides, as banded applications to the interrow may overcome the apparent problem of crop phytotoxicity. Chlorthal at rates that gave good grass control had no adverse effect on Townsville stylo (Stylosanthes humilis). This could be an important advantage when sorghum is sown in rotation with Townsville stylo pasture or where the crop is undersown with Townsville stylo.