SPECIES IDENTIFICATION AND PATHOGENICITY STUDY OF FRENCH COLLETOTRICHUM STRAINS ISOLATED FROM STRAWBERRY USING MORPHOLOGICAL-CHARACTERISTICS AND CULTURAL-CHARACTERISTICS

This study reports for the first time the identification and character ization of Colletotrichum spp. of anthracnose isolates originating fro m strawberry grown in France. Sixteen French isolates of Colletotrichu m and six North American isolates (also from strawberry) representing C. acutatum, C. gloeosporioides, and C. fragariae were compared with r espect to morphological and cultural criteria. Fourteen of the French isolates were identified as C. acutatum, characterized by acute conidi a and low growth rates. The remaining two isolates were identified as C. gloeosporioides (teleomorph, Glomerella cingulata), characterized b y cylindrical conidia, production of perithecia, and high growth rates . C. fragariae was not found among the French isolates. Pathogenicity of C. gloeosporioides and C. acutatum isolates was evaluated on five s trawberry cultivars: cvs. Elsanta and Valeta (susceptible), Addie (int ermediate), and Sequoia and Dover (resistant). Isolates of C. gloeospo rioides had low pathogenicity while C. acutatum isolates varied from s lightly to very pathogenic. Some [isolate x cultivar] specificity was detected, and based on this interaction C. acutatum was classified int o two groups. Isolates in group 1 caused a similar disease severity on Addie, Sequoia, and Dover, whereas those of group 2 were virulent on Addie but nonvirulent on Sequoia and Dover.