Differentiation Of Isolates Of Uromyces Appendicuiatus (per. Ex. Per. ) Unger V A R .appendicuiatus And Evaluation Of Bean Cultivars For Resistance To Bean Rust In Kenya.

Abstract

Bean rust caused by Uromyces appendiculatus (Per. ex. per) Unger val'. 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 in Kenya were differentiated using 20 differential cultivars. Inoculation was done by spraying a urediospore suspension onto the primary leaves of nine-day old seedlings, 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 for resistance to a mixture of specific isolates from different sites. The cultivars NB 2405 and NB 132 were immune and NB 123, NB , ", "' 14, NB 127,NB 225 and NB 63·'were highly resistant. It was found that rust isolates from different site's may cause different; react'ions on the same host due to variability of the rust 'fungus, and the cultivars identified as either immune or highly resistant resistance were in the recommended as varieties in Kenya. development possible of resistant sources of bean