THE DIVERSITY AND OVERWINTERING OF COLLETOTRICHUM-COCCODES IN TOMATO FIELDS IN SOUTHWESTERN ONTARIO

At least fifteen distinct biotypes of Colletotrichum coccodes were cha racterized from 435 isolates obtained from diseased tomato (Lycopersic on esculentum) fruit and leaves of various commercial processing tomat o cultivars and breeding lines. These biotypes differed in pathogenici ty, spore production, spore size, growth rate and cultural characteris tics in potato dextrose agar. The differences in pathogenicity were de monstrated by inoculations made on mature green fruit of several tomat o cultivars. Spores of C. coccodes were able to overwinter in infected plant debris in the field. Since the fungus can overwinter in southwe stern Ontario and also parasitize a local common weed (velvetleaf) and potato, it is evident that these biotypes should be stable in this re gion if introduction from outside is prevented.