Pest management in cowpea. Part 2. Integrating planting time, plant density and insecticide application for management of cowpea field insect pests in eastern Uganda

The focus of this study was to formulate a cost-effective pest management strategy for cowpea growers in Uganda. An initial experiment examined the influence of different times of planting and plant densities on infestation levels of the major field pests of cowpea. Results indicated that planting at the on-set of rains, at 30 x 20 cm² or 60 x 20 cm² gave better yields. Here, we studied the effect of time and frequency of insecticide application on the field pests infestations. Results showed that a single spray at budding, flowering and podding had the highest marginal returns (3.12) in comparison to spraying throughout the season (1.77) and at seedling, flowering and podding stages (2.18). The best treatments from these two experiments were combined and compared to the single control measures, and the untreated control. Cowpea grain yields and marginal returns from plots receiving combined control measures were higher than those from plots receiving only cultural or chemical control measures. Our study provides evidence that a few well-timed sprays in combination with cultural practices are not only effective but also very profitable. (C) 2000 Elsevier Science Ltd.