Evaluation of the electrodynamic spraying technique for cowpea pest control

Eight electrodynamic (ED) insecticide formulations were compared with an emulsifiable concentrate for the control of major cowpea pests. All insecticides except one were double product formulations. The results showed that, in general, the ED formulations gave better control of the insects and produced better grain yields than the emulsifiable concentrate (P < 0.05). A cost-benefit analysis revealed also that the use of the electrodynamic spraying technique could result in a 2-fold return to the farmer. In a second trial to determine an appropriate spray schedule based on one of the best ED formulations, three treatments per crop season at 14-day intervals were found to be better than two for the medium-duration cowpea cultivar TVx 3236 but not for the extra-early cultivar, IT 84E-124, for which neither spray interval nor frequency of treatment made any significant difference in crop yield. It is suggested that 'earliness' provides an escape from the later infestation by coreid bugs -an important consideration in determining an extended insecticide regime for this crop.