Effects of Ratooning and Protection from Diseases and Birds on Seed Production in Guinea Grass

Effects of ratooning and protection from diseases and birds on seed production in guinea grass (Pannicum maximum L.) were assessed in a study from October 1986 to April 1987. Treatments included ratooning and mancozeb application with or without protection from birds (netting). Highest yield occurred with combined netting and mancozeb application. Mancozeb sp,aying without netting gave lower seed yield than netting without fungicide spraying. Seed yield, which generally decreased with ratooning, was lowest among unnetted and unsprayed crops. Prom anthesis to seed maturation lasted, on average, 9 days, and seeds borne on the upper part of the panicle matured earlier than those borne at the lower part. Disease infection became pronounced just after grain filling, and was more severe in October and November than in February and March. Fungal disease was the most prominent seed disease in guinea grass; the fungus largely responsible was Ustilago spp.