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 characterization of Colletotrichum spp. of anthracnose isolates originating from strawberry grown in France. Sixteen French isolates of Colletotrichum and six North American isolates (also from strawberry) representing C. acutatum, C. gloeosporioides, and C. fragariae were compared with respect to morphological and cultural criteria. Fourteen of the French isolates were identified as C. acutatum, characterized by acute conidia and low growth rates. The remaining two isolates were identified as C. gloeosporioides (teleomorph, Glomerella cingulata), characterized by 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 strawberry cultivars: cvs. Elsanta and Valeta (susceptible), Addie (intermediate), and Sequoia and Dover (resistant). Isolates of C. gloeosporioides had low pathogenicity while C. acutatum isolates varied from slightly to very pathogenic. Some [isolate x cultivar] specificity was detected, and based on this interaction C. acutatum was classified into 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.