Weed competition in irrigated cotton (Gossypium barbadense L.) and groundnut (Arachis hypogaea L.) in the Sudan Gezira

Abstract

Summary:Losses of crop yield due to weed competition in unweeded plots averaged nearly 60% of weed‐free yields in cotton and 70% in groundnuts. Weed competition was not directly related to weed groundcover but was dependent on the seasonal growing conditions. The critical period of weed competition in both crops was the 6 weeks between 4 and 10 weeks after crop emergence. During this period cotton could tolerate up to 25% weed groundcover without appreciable loss in crop yield. Groundnuts could tolerate not more than 10% weed cover before yield loss occurred. A main factor in achieving standards of weed control within these limits was preventing the early growth of monocotyledonous weed species: pre‐sowing application of trifluralin and benfiuralin provided this over a wide range of growing conditions.