EVALUATION OF NEW HERBICIDES FOR MANAGEMENT OF BLACK NIGHTSHADE (SOLANUM NIRGRUM) IN PROCESSING TOMATOES

Black nightshade (Solanum nigrum L.) is a significant cost to processing tomato production. The weed is difficult to control selectively as it is a member of the same family as tomatoes (Lycopersicon esculentum Mill.). Eight field trials have been conducted in direct seeded and transplanted crops over two seasons. Pendimethalin, s-metolachlor, isoxaflutole and the experimental herbicides sulfentrazone and dimethenamid, all showed high selectivity to transplanted tomatoes with effective control of black nightshade and other weeds. Clomazone, at a rate of 480g ai ha^-1, was phytotoxic to transplanted tomatoes at some sites. A number of the herbicides, which have shown high selectivity to transplanted tomatoes, caused damage to direct seeded tomatoes. Further work with herbicides is required in direct seeded tomato crops. A permit application for metolachlor has been submitted to the National Registration Authority and a permit application for pendimethalin will be submitted once the crop residue analysis has been completed.