Abstract

Cowpea production is common among smallholder subsistence farmers of Western Kenya due to its wide ecological adaptation. However, this crop is affected by cowpea rust Uromyces phaseoli var vignae (Baarel) Arth disease, causing economic yield losses with limited control measures. This study therefore, evaluated cowpea rust disease incidence (DI) and severity (DS) on growth of selected improved cowpea genotypes. A Randomized Complete Block Design (RCBD) in split plot arrangement experiment was conducted in Busia and Kakamega counties, Kenya during short rains of 2018 and long rains of 2019. Cowpea genotype: K80, KVU 27-1, Tumaini, Dakawa and local variety was the main factor and cropping system: pure stand cowpea and cowpea intercropped with maize was the sub plot-factor. Data were subjected to Mixed model ANOVA using SAS. The DI and DS were 41 and 39% respectively less in Dakawa and Tumaini with more cowpea leaf and grain yields compared to other genotypes. On the other hand, DI and DS were 35 and 56% respectively less in pure stand cowpea compared to intercrop cowpea. Pure stand cowpea also had more leaf and grain yields. The results indicate that Dakawa and Tumaini cowpea genotypes have potential resistance to cowpea rust and the conditions could be improved by planting cowpea in pure stand.

Key words: Cowpea genotype, cropping system, cowpea rust incidence, severity.