Abstract
Cowpea [Vigna unguiculata (L.) Walp.] is a potential crop in the Delaware, Maryland, and Virginia (Delmarva) peninsula region, U.S.A., which is a drought-prone area with predominantly sandy soils. Insect pests could cause significant losses in the seed yield if not controlled. There is no information on the number of minimum sprays for the management of cowpea pests 10 this region. Studies were conducted to evaluate the effect of minimum number and timing of insecticide sprays. The number of sprays varied from one to two. The sprays were started at 5% flowering and 5% podding stages, followed by second spray applications after 15 days. The results showed significant increase in the seed yield of cowpea in treatments which received the insecticide sprays. Also, there was a significant reduction in infestation of cowpea pod borers in the insecticide treatments compared with the control, especially in the second experiment which was sprayed with a mixture of insecticides (cypermethrin + dimethoate). However, in the first experiment which received spray application of endosulfan, the infestation percentage of insecticide treatment was similar to the control, probably due to lack of residual effect of endosulfan. It was concluded that one spray application at 5% podding could provide significant increase in the seed yield of cowpea and could also reduce the percentage infestation of pod borers. The number of pod sucking bugs and corn earworm larvae was also significantly reduced in the spray treatments. The minimum spray application needs to be integrated with other insect pest management practices such as time of planting and host crop resistance. Also, threshold levels for key pests need to be evaluated.
