Crop and Weed Response to Diuron in the Rain Forest Zone of Ghana
A series of experiments were carried out to evaluate a residual herbicide containing 800 g kgG1 Diuron present as 3-(3,4-Dichlorophenyl)-1,1-dimethylurea water dispersible granules for weed management in 2012. The experiments assessed the effect of Diuron on selected annual weeds, cowpea and maize when applied pre and post-emergence. The rates of Diuron evaluated ranged from 0-2.0% for potted weeds and trays and 0-4% for phyto-toxicity and field tests. Data taken included damage caused to potted weeds and crops, crop emergence, leaf chlorophyll content, survival and dry matter accumulation of cowpea and maize at 6 weeks after application. The results show that 1% Diuron solution easily controlled the weed species present with the exception of Rottboellia granularis and Commelina diffusa. When applied pre-emergence, Diuron killed all the cowpea and maize plants that emerged within 2 and 3 weeks after sowing, respectively. With the exception of the 4% solution, early post-emergence application was found not to be lethal to cowpea and maize although rates above 2% affected both growth and dry matter accumulation of these crops. It was, therefore, recommended that Diuron at 1.0% solution (2 kg haG1 in 200 L of water) be used for early post-emergence weed management in cowpea and maize in the forest zone of Ghana and places of similar agro-ecologies.