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Cowpea is attacked by a wide spectrum of insect pests that ravages the crop in the field at different growing stages sometimes resulting into complete crop failure. In order to reduce insect pest damage, increase cowpea grain yield and other yield related components, an experiment was conducted using five improved cowpea cultivars and one local check, two planting dates and two spraying regimes across two major agro-climatic zones during 2012 and 2013 cropping seasons. The experiment was laid out in a randomized complete block design with three replications at three locations Sumbuya, Serabu and Nguala.
Result showed that the effect of cultivar, planting date and spraying regime on the measured parameters were highly significant. Also interaction effect of cultivar, planting date and spraying regime on the measured parameters were all significant. Grain yield, pod load and biomass were higher in sprayed plots compared to unsprayed plots. Also, grain yield and pod load were higher when planting was done in September. Furthermore, all the improved varieties out yielded the local variety.
Days to 50% flowering and maturity were shorter for all the improved varieties compared to the local variety with spraying plots flowering and maturing earlier when planting was done in September compared to June.
These results shows that integrating cowpea cultivar with date of planting alongside minimal application of insecticide can lead to the reduction in cowpea insect pests across the major agro-ecological zones of Sierra Leone thus, resulting into increase in grain yield and other yield related components of cowpea.
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