International Journal of Agricultural Sciences

International Journal of Agricultural Sciences ISSN 2167-0447 Vol. 7 (2), pp. 1248-1257, February, 2017. © International Scholars Journals

Full Length Research Paper

Effects of variety and insecticide spray application on pest damage and yield of cowpea

¹Ndiso J. B., ²Chemining’wa G. N., ²Olubayo F. M. and ¹Saha H. M.

¹Department of Crop Sciences, Pwani University, P.O.Box 195 – 80108, Kilifi, Kenya,

²Department of Plant Science and Crop Protection, University of Nairobi, P.O.Box 30197 00100 GPO, Nairobi, Kenya. 

Received 05 October, 2016; Revised 28 January, 2017; Accepted 03 February, 2017 and Published 27 February, 2017

Abstract

Experiment was conducted at Pwani University farm under irrigation to evaluate the effects of variety and insecticide spray application on pest damage and yield of cowpea. Randomized complete block design with a split plot arrangement was used and replicated thrice. Main plots were two pest management levels while the sub-plots included cowpea varieties. Data collected included: insect pest damage at pre-flowering, flowering, podding and maturity stages, number of pods per plant, number of grains per pod, 100-grain weight and grain yield. Data subjected to analysis of variance using the SAS statistical package. Insecticide application reduced pest damage at pre-flowering, flowering and podding by 23.5%, 20.6% and 52.3%, respectively. Pod borer damage was 49.9% lower in sprayed than unsprayed plots. Insecticide application significantly increased cowpea grain yield, with the increase ranging from 11.6% in Nyekundu to 662.5% in Macho. Varieties such as KVU 419, Macho, Kaima koko and Nyeupe had lower pod borer damage than K80, Mwandato and Nyekundu which had the highest damage under no insecticide spray. All cowpea varieties were similarly affected by insect pests, indicating that application of insecticide is necessary for sustainable cowpea production. Insecticide spray at podding stage is more critical than at pre-flowering and flowering stages.

Keywords: Cowpea, insecticide, pest, spray, varieties.