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 s trategy for cowpea growers in Uganda. An initial experiment examined the in fluence of different times of planting and plant densities on infestation l evels of the major field pests of cowpea. Results indicated that planting a t the on-set of rains, at 30 x 20 cm(2) or 60 x 20 cm(2) gave better yields . Here, we studied the effect of time and frequency of insecticide applicat ion on the field pests infestations. Results showed that a single spray at budding, flowering and podding had the highest marginal returns (3.12) in c omparison to spraying throughout the season (1.77) and at seedling, floweri ng and podding stages (2.18). The best treatments from these two experiment s were combined and compared to the single control measures, and the untrea ted 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 f ew well-timed sprays in combination with cultural practices are not only ef fective but also very profitable. (C) 2000 Elsevier Science Ltd. All rights reserved.