Evaluation of integrated weed management practices for maize in the northern Guinea savanna of Nigeria

Field trials were conducted in 1999 and 2000 in the northern Guinea savanna of Nigeria to evaluate the potential of several weed management practices to reduce early weed competition in maize. The treatments were different combinations of the herbicide mixture metolachlor + atrazine at 5 L ha(-1), the cover crop velvetbean (Mucuna cochinchinensis), hoc! weeding at 2, 4, and 6 weeks or at 4 and 8 weeks after planting (WAP) maize, maize density: high (60,000 plants ha(-1)), medium (40,000 plants ha(-1)), low (25,000 plants ha(-1)) and a farmer's control consisting of a single weeding at 4 WAP and low maize density. Results showed that maize grain yield was significantly higher in the treatment in which either the herbicide mixture or velvetbean was combined with 40,000 maize plants ha-1 and weeded thrice. The lowest maize grain yield was obtained with the farmer's control. Weed dry matter was 60% more in the farmer's control than in velvetbean combined with 40,000 maize plants ha(-1) and weeded three times. The farmer's control was higher in weed species diversity with Setaria pallide-fusca, Vernonia galamensis, and Boerhavia erecta as the dominant species. Sporobolus pyramidalis and Thelepogon elegans were the dominant weeds in the herbicide treatment and velvetbean plots, respectively. Herbicide or velvetbean in combination with medium maize density and weeding three times (2, 4, and 6 WAP) is recommended for weed management in the northern Guinea savanna. (C) 2004 Published by Elsevier Ltd.