Chemical Control of Weeds in Cotton in the Sudan Gezira

Abstract

Abstract Early work on chemical weed control in the fallow towards the end of the Second World War is reviewed briefly. Attempts to use contact residual herbicides as pre-emergence applications in the early 1950s are also described. Pre-sowing applications of residual herbicides were found more phytotoxic to cotton than pre-emergence applications. The closer the time of pre-sowing application to cotton sowing, the more effective was suppression of weeds competing with cotton. Mechanical cultivations and particularly disc ploughing and rotovation to a depth of more than 15 cm were found more effective in the control of Cynodon dactylon than pre-sowing herbicide applications. Fluometuron, noruron and prometryne were found very effective as pre-emergence herbicides. Optimum rates of application were found to be only 25-50% of rates recommended for the USA and other countries. Resistant weeds included Cyperus rotundus, Cynodon dactylon, and Rhyncosia memnonia. A large-scale trial with fluometuron, covering 12...