Minimising Insecticide Application in the Control of Insect Pests of Cowpea (Vigna Unguiculata (L) WALP) in Delta State, Nigeria

Many commercial cowpea farmers control insect pests on cowpea with synthetic chemicals and may sometimes spray their farms during the growing season as many as 8 to 10 times. This leads to health hazards and environmental pollution. The present study was conducted to reduce the number of times, cypermethrin (conventional chemical) is applied before harvest and still, produce the expected cowpea grains. The experiments were carried out in two agro-ecological zones - Asaba and Abraka of Delta State during the late cropping season. The experiments consisted of 4 treatments - cowpea plots sprayed 4 times (at 7 days’ intervals), cowpea plots sprayed 5 times (at 10 days’ intervals), cowpea plots whose insect infestation were monitored before chemical application and control plots (without chemical treatment). Each treatment was replicated 3 times. The experiments were organised into a randomised complete block design (RCBD). The results indicated that cypermethrin controlled the major insect pests of cowpea. Second, grain yield was high at both locations; significant differences did not exist (P>0.05) in insect number and grain yield among the treatments. The study provides the evidence that (i) high cowpea grain yield is obtained at reduced number of chemical application of 4 or 5 times during the growing season (ii) Grain yield was significantly (P<0.05) higher at Abraka with1400.60kg ha-1 than Asaba (714.40kg ha-1) during the late cropping season.