Growth and yield in maize/cassava intercrop as affected by interactions of weed control methods

The response of food crops to integrated weed management involving the used of pre-emergence herbicides, hoe-weeding and live mulch of herbaceous cover plants in a maize/cassava intercrop was investigated at the Teaching and Research Farm of the University of Ilorin between 2002 and 2004. The experiment consisted of eight main treatments and six sub treatments. The main treatments were made of the application of two of pre-emergence herbicides (Primextra and Galex each at 2.5kg a.i./ha alone, or with one or two supplementary hoe-weeding at 6 weeks after planting (WAP) or 6 and 12WAP), a hoe-weeded check (hoeing at 3, 6 and 12WAP) and a weedy control. The sub treatments consisted of five legume cover crops (Pueraria phaseoloides, Stylosanthes guianesis, Mucuna pruriens var. utilis, Mucuna preta and Mucuna jaspeada) and a no legume cover plot as control. Data were collected for the vegetative and reproductive parameters for both crops. Results showed that the various treatment combinations supported good vegetative growth in maize except at 9WAP where plots treated with Galex alone under the mucuna species produced significantly shorter plants as in weedy plots. However, cassava plant height was significantly higher in plots with 3 hoe-weeding under S. guianensis cover and Galex + 2HW without legume (NL) cover at 12 and 16WAP respectively, compared to other treatment combimnations. Maize grain yield was significantly higher in the treatment combination involving Primextra with two hoe-weeding under M. pruriens var. utilis cover for both years while average cassava fresh tuber yield was significantly higher in the combination involving Primextra with two hoe-weeding under Pueraria Phaseoloides. Maize grain yield and cassava fresh tuber yield in treatment combinations of the two pre-emergence herbicides alone under the various cover crops produced yields that were not significantly different from what was obtained in weedy plots.