EFFECTS OF CYPERMETHRIN + DIMETHOATE AND EXTRACTS OF PIPER-GUINEENSE AND AZADIRACHTA-INDICA ON THE PESTS AND YIELD OF COWPEA, VIGNA-UNGUICULATA

Field trials were conducted in 1988 at the University of Ibadan to determine the effects of cypermethrin + dimethoate (Sherpa Plus®), the oil extract from ripe seeds of Piper guineense Schum & Thonn and the aqueous extract of ripe seeds of Azadirachta indica A. Juss on the pests and yield of cowpea. Cypermethrin + dimethoate was consistently superior to all other treatments in substantially reducing the population densities of Megalurothrips sjostedti Trybom and of Maruca testulalis Geyer, which are serious pests on flowers and buds, and in reducing the densities of four pod-sucking bugs. Pest population densities were also reduced by foliar sprays with A. indica or P. guineense extracts. Seed yield after treatment with cypermethrin + dimethoate was 0-99 t/ha, more than double the yield from other treatments. A marginal increase in seed yield compared with the control was achieved by foliar spraying with A. indica extract. © 1990, Cambridge University Press. All rights reserved.