Effects of Common Bean ( Phaseolus vulgaris L.) Cultivars and Their Mixtures with Other Legume Species on Bean Foliage Beetle ( Ootheca spp ) Incidence, Severity and Grain Yield in Western Kenya

Abstract

Bean foliage beetle injury is a major constraint to common bean production. The objective of the study was to evaluate the effect of mixtures of bean cultivars and legume species on the bean foliage beetle incidence, severity of damage and grain yield of beans. Field experiments were conducted at four sites in Busia County in western Kenya in 2015. A total of 21 and 22 farmers participated during the long and short rains seasons respectively. The sites were located between 34 40 and 34 22 East longitude and latitude 010 N 0 20 North and at the altitude ranging 1139 and 1265 m.a.s.l. Bean foliage beetle leaf damage incidence (74.5%) and pod damage incidence (77.6%) was significantly higher in the long than short rain season. Grain yield was significantly higher (2.2t ha-1) in the long rains than (0.9t ha-1) in short rains season. Foliage beetle incidence was significantly reduced by 15% in plots with mixed bean cultivars compared to monoculture. Severity of pod damage was reduced by 10% but the incidence of pod damage increased by 15.4% in plots of mixed bean cultivars during the long and short rain season respectively. Grain yield was 0.5 and 2.4t ha-1 in monoculture plots compared to 0.8and 2.2t ha-1 in plots of mixed bean cultivar during the long and short rain seasons respectively. Foliage beetle incidence was positively correlated to pod damage (r =0.2, p=0.0021). These results indicate that mixed cropping systems has potential in bean foliage beetle management. Combining such systems with use of resistant germplasm and proper cultural practices could reduce bean foliage beetle damage and increase bean yield.