RESISTANCE TO COLLETOTRICHUM-LINDEMUTHIANUM ISOLATES FROM MIDDLE AMERICA AND ANDEAN SOUTH-AMERICA IN DIFFERENT COMMON BEAN RACES

A total of 20,144 common bean (Phaseolus vulgaris) accessions were eva luated in the field at CIAT-Popayan, Colombia, with a mixture of local isolates of the anthracnose pathogen, Colletotrichum lindemuthianum. Of these, 4,939 (24.5%) accessions were resistant, and another 4,410 ( 21.9%) showed an intermediate reaction between resistant and susceptib le. These accessions were then inoculated at the seedling stage in the screenhouse at the same site with the same mixture of isolates. The 3 ,778 accessions showing resistance were subsequently challenged in a g reenhouse at the seedling stage, with a mixture of isolates from Middl e America and separately with a mixture from Andean South America. Res istance to all isolates was found in 1,270 accessions, and of these, 3 50 (1.7% of total) were immune. These sources of resistance included r epresentatives from all six races of cultivated common bean and showed variation for growth habit, maturity, seed color and size, adaptation traits, and geographical origin. Also, 68 resistant accessions were w ild common beans from Middle America and Andean South America.