First report of race 485 of Colletotrichum lindemuthianum in Kenya and its implication in bean resistance breeding

Four isolates of Colletotrichum lindemuthianum were collected in 1997 from bean seeds produced in Rongai in Nakuru District. Characterisation of the isolates using the twelve internationally recommended differential bean cultivars and the Binary System of classification demonstrated that the four isolates were similar and were classified as race 485. The characterisation of race 485 is yet the first report of such a race in Kenya. It lacks virulence genes against the Are gene evidenced by incompatible reaction with cultivar 'Cornell 49-242'. The new race therefore poses no threat to the bean genotypes with Are gene. However it poses a great threat to the popularly grown Kenyan beans which have no Are gene. It seems to have more virulence genes than races so far reported in Kenya. This implies that the host may require more resistant genes to stand the increased virulence genes and therefore maintain a long-term durable resistance.