Studies on the Influence of Insecticide Spraying Regimes and Cultivars on Insect Pests and Grain Yield of Cowpea in the Semi Arid Zone of Nigeria

DEGRI, M.M, MAILAFIYA, D.M. AND MAINA, Y.T.

Department of Crop Protection,

University of Maiduguri, Borno State, Nigeria.

E-mail: mikedegri@gmail.com

ABSTRACT

Field experiments were carried out during 2010 and 2011 cropping seasons at the Teaching and Research farm of the Department of Crop Protection, Faculty of Agriculture, University of Maiduguri the aim is to evaluate the influence of insecticide spraying regime and variety on the infestation of cowpea varieties by pod sucking bugs in the semi arid zone of Nigeria. The experiment was laid out in a randomized complete block design in a split plot with four varieties CIT 89 KD – 288, IT 90K – 277 – 2, Borno brown and Banjaram as main plots and four insecticide spray regimes (one each at flower buds, full flowering, early podding and pod filling stages) as subplots all replicated three times. Data were collected on insect pest count, pods/ plant, undamaged pods/ plant, damaged pods/ plant, normal seeds/ pod, 100 seed weight and grain yield. Result showed that varietal resistance and spraying regimes had significant effects on insect pest populations and yield parameters of improved cowpea varieties (IT 89KD – 288 and IT 90K – 2772- 2). Significantly reduced insect pest populations, pod damaged while increasing the number of pods/ plant, undamaged pods/plant, normal seed per pod, seed weight and grain yields. Compared to the local cowpea varieties (Borno brown and Banjaram) four applications of insecticide once each at flower buds, flowering, early podding and pod filling stages significantly reduced pod and seed damage, insect populations resulting in substantial increase in grain yield of cowpea compared to one application. Combined effect of variety and spray regime showed that all the varieties sprayed four times had significantly lower insect pests populations, damaged pods, undamaged pods, normal seeds, seed weight and grain yield. This study therefore indicates that varietal resistance and four spray regimes provided adequate protection for cowpea thus reducing cowpea losses on the field.