Races of <i>Colletotrichum lindernuthianum</i> and implications for bean breeding in Uganda

Abstract

SUMMARY Nineteen local isolates of the bean anthracnose pathogen have been obtained and tested over the period 1964–70 for pathogenicity on a set of differential cultivars including the sets of four cultivars each used in the alternative systems of Schreiber and Hubberling and of Bannerot and Blondet. The results indicate the existence of a number of races not conforming to those of either system and the ability, when freshly collected, of some isolates with affinities to both α and β races partially to overcome the immunity of the cultivar Cornell 49–242. The implications of the position as now known from these results and a review of the literature for disease‐resistance breeding are discussed. Tests of the Uganda isolates, on a range of other dry bean cultivars, indicate a tendency for α and δ races to be pathogenic on small‐seeded indeterminate viny or indeterminate bush cultivars, whereas β and γ races tend to be pathogenic on larger‐seeded and determinate cultivars.