Abstract

During 1995 the reaction of bean genotypes from different origin to Xcp was scored under greenhouse conditions at the Valle de Mexico Experimental Station of INIFAP. Three experiments were made with a)120, b)44 and c) seven bean genotypes. Plants of a and b at the V3 stage were inoculated with razor blades using a mixture of nine Xcp strains, and c individually with seven different strains of Xcp with different grade of virulence. The disease severity was scored 20 days after the inoculation comparingwith a visual scale of nine grades. Data were analyzed under a completely random design. In a the genotypes that showed resistant reaction were: A 36, A 475, G 5686, G 11867, Harowood, SEA 14, XAN 266, MCD 4012 and REN 27. In b the resistant genotypes were: Sequía Durango, Taylor and XAN 30. The disease severity of all genotypes in each experiment showed a normal distribution, with the maximum number of genotypes at the five grade of severity in the first trial and six in the second. The resistant genotypes in the last trial showed a differential reaction and genotype by strain interaction, REN 27 and SEA 14 proved to be resistant to most of the strains inoculated. These results indicate that the inoculation of mixtures of Xcp strains with different pathogenicity was efficient to identify resistant bean genotypes.