Diuron as a pre-sowing herbicide for cotton in the Ord River Valley

Abstract

When cotton is sown in the middle of the wet season on the Ord River Valley, the formation or ridges and the control of weeds present major problems. One solution would be to complete the final land preparation, including the formation of the ridges, at the end of the dry season (November), and to spray with a herbicide, such as diuron, at the end of the dry or at the onset of the wet season. Four experiments concerned with this system are described. When diuron at 1 1/2-2 lb active ingredient an acre was applied during the dry season or at the beginning of the wet, cotton sown two weeks after spraying was not damaged and weeds were controlled throughout the growing season. When diuron was applied later on in the wet season (January-February), cotton could not be sown without seedling damage until approximately six weeks after spraying. Residues from annual applications of pre-sowing diuron to the same area did not accumulate fast enough to damage subsequent cotton crops.