Evaluation of Common Bean (Phaseolus vulgaris L.) Varieties for Resistance to Bean Stem Maggot (Ophiomyia spp.) in Kenya

Common bean is the most important pulse crop in Kenya, though small scale farmers involved in its farming have limited access to quality seeds resistant to pests such as bean stem maggot, thereby limiting its production from potential yield production of 2000 kg ha-1 to less than 1000 kg ha-1. This study was therefore aimed at determining effective ways of managing bean stem maggot through identification and selection of resistant commercial varieties for enhanced host resistance. This was achieved through screening levels of resistance among commercial varieties and determining severity and incidence of bean stem maggot infestations. The study was conducted in Kakamega, Njoro and Uasin-gishu. The varieties were planted together with two local checks; KK 8, Tasha, KK 15 (Resistant check), Chelalang, Wairimu dwarf, Ciankui, GLP 585, Miezi mbili, GLP 2 (Susceptible check), GLP 1004, GLP 24, and GLP 1127. A score of 1-9 scale (1-3 highly resistant, 3-5 resistant, 5-7 susceptible and 7-9 highly susceptible) was used. The experimental design used was RCB (Randomized Complete Block) design with three replications. Data collected was subjected to ANOVA using SAS program version 9.1, considering varieties as fixed and replicates as random factors. The results showed that the bean varieties resistant to bean stem maggot were; Chelalang, Tasha, GLP 1004, KK 8, GLP 585 and KK 15. The resistant varieties deter bean stem maggot attack and are recommended for use by farmers in the country.