Evaluation of French Bean (Phaseolus vulgaris L.) Varieties for Resistance to Anthracnose

Abstract

French bean (Phaseolus vulgaris L.) is a very important protein component of the diets of the majority of the population globally and in Kenya. It is a major vegetable export crop (48%) and income earner to the smallholder farmers who constitute more than 80% of producers in Kenya.  However commercial varieties presently grown have the potential to produce more yields of above 1800 kgha-1 but are limited by pests and disease. Among the diseases is anthracnose incited by Colletotrichum lindemuthianum (sacc.et. magn.) Lams. Scrip which causes a severe rapidly developing disease that can bring about complete plant defoliation and extensive yield and or quality loss. Studies were conducted to identify commercial varieties of French beans which are resistant to anthracnose disease. The objective of this study was to screen commercial varieties of French beans in controlled environmental conditions (glasshouse) for resistance to anthracnose disease. This was achieved through evaluation of incidence and phenotypic variation in anthracnose virulence among the bean varieties in relation to yields. Ten bean varieties were used during the study, among them were two controls; Julia, Andate, Amy, Organdia, Mara, Serengeti (resistant control), Venda (susceptible control), Conza, Strada and MuH13. The experimental design used was Randomized Complete Block Design (RCBD) with four replications. A scale of 1-9 score was used to rate the disease reaction, which was subdivided into; 1-2 (resistant), 3-4(moderate), 5-9(susceptible). Data collected were subjected to ANOVA using SAS program version 9.1. Results exhibited three bean varieties (Julia, MuH13 and Organdia) to have high significant resistance to anthracnose and one variety (Strada) to be tolerant. The study therefore suggests the use of desirable resistant varieties as the best way of increasing yields.