FIELD EVALUATION OF NEEM SEED EXTRACTS FOR THE CONTROL OF MAJOR COWPEA PESTS IN NORTHERN GHANA

Abstract

Field studies were conducted at the Experimental Farms of the CSIR-Savanna Agricultural Research Institute (SARI), Nyankpala, Northern Ghana, during the 2004 cropping season, to evaluate the effect of aqueous neem (Azadirachta indica A. Juss) seed extracts at 5%, 10%, 15% and20% on major insect pests namely; Aphis craccivora Koch., Megalurothrips sjostedtri Tyrb., Maruca vitrata Fab., and a complex of pod- and seed sucking bus and their effect on grain quality and fodder yield of copea (Vigna unguiculata L. Walpers). The incidence and abundance of all the target insect pests were significantly affected in a dose-dependent manner by the neem seed extract treatments. Cowpea grain y8ield was significantly higher in all neem-treated plots than the control plot. The 15% neem seed extract treatement proved as effective as that of the 20% in increasing the grain yield of the cowpea crop. However, none of the neem seeed extract treatements was comparable to the synthetic inseciticide (Karate) in terms of copwera grain yield. Grain quality obtained from the 15% or the 20% neem extract treatements was however as high as that obtained from the Karate insecticicde treatment. Cowpea fodder yield was found to decrease with incraing concentration of the extract, with the 5% extract treatment recording the highest fodder yield. Cost-benefit analysis from the grain and fodder yields indicated that the 15% extract treatment recording the highest fodder yield. Cost-benefit analysis from the grain yields indicated that the 15% and 5% neem extract treatments respectively, gave the best cost-benefit ratio. This seemed to suggest that 5% and the 15% neem seed extract treatments were the most profitable for use in controlling the mjor field pest of the cowpea crop for maximum economic returns in cowpea as fodder and grain, respectively, in the stud area.The Savanna Agricultural Institute (SARI) has made it and objective to develop a more comprehensive Integrated Pest Management (IPM) strategy for cowpea farmers in the savnna ecology of Ghana, using low-cost and residue-freee natural insecticides. The use of aques oextracts fro, neem seeds is thus, a possible innovation in this direction. The implication attempt to further contribute to knowledge in the use of neem se detracts in the control of cowpea pest in Ghana.