"Differentiation of Isolates of Uromyces Appendiculatus (Per. Ex. Per) Unger Var. Appendiculatus and Evaluation of Bean Cultivars for Resistance to Bean Rust in Kenya".

Abstract

Bean rust caused by Uromyces appendiculatus (Per.ex. per) Unger var appendiculatus Is an important disease of beans in Kenya. Work was carried out on this disease to investigate the variability of the pathogen in Kenyan rust isolates and to evaluate bean cultivars for resistance to rust. Rust isolates from four different sites il. Kenya were differen· iated using 20 differential cultlvars. Inoculation was done by spraying a ured i ospclre suspension onto the primary leaves of nine-day old seed lings, which were then incubated for 24 hours in the greenhouse. Host reactions were recorded 14 days after inoculation. The host-pathogen interactions indicated variability of Uromyces appendiculatus among the isolates from the different sites. Seventy-seven cultivars were evaluated fJr resistance to a mixture of specific isolates from different sites. The cultivars NB 2405 and NB 132 were !mm~ne and NB 123, NB 14, NB 127,NB 225 and NB 63 were high1y resistant. It was found that rust isolates from different sites may cause different reactions on the same host due to variability of the rust fungus, and the cultivars identified as either immune or highly