Field Evaluation of the Efficacy of some Plant Oils for the Management of Aphis craccivora (Koch)

The Research was conducted to evaluate the efficacy of Jatropha curcas (L.) and Azadirachta indica (A. Juss) for the management of Aphis craccivora (Koch) infesting cowpea. The experiment was laid out in a Randomized Complete Block Design. The result indicated that, of the plant oils, 2 and 3 % concentrations of J. curcas and A. indica oil gave the highest reduction in A. craccivora population and the number of leaf curls per plant. Also, significantly (P≤0.05) longer vines, a higher number of pods and a higher of 100 seeds weight were obtained from cowpea plants with the application of J. curcas and A. indica respectively, compared with their respective control. The result also indicated that the application of 1, 2 and 3 % concentrations of A. indica oil led to an average of 8.42, 39.63, and 64.31 per cent increase in the total grain yield, respectively when compared with the control, while 1, 2 and 3 % concentrations of J. curcas oil resulted in 25.39, 47.27 and 69.66 % increases in the cowpea total grain yield, respectively when compared with the control. The application of Lambda-cyhalothrin led to a 69.74 per cent increase in grain yield. Jatropha curcas oil resulted in a higher grain yield than A. indica oil and compared favourably with that of Lambda-cyhalothrin. The results suggest that both oil extracts can be used by cowpea farmers for effective management of A. craccivora infesting cowpea.