GENETIC AND PATHOLOGICAL DIVERSITY OF THE MANGO ANTHRACNOSE PATHOGEN IN FLORIDA

The mango (Mangifera indica L.) is a major fruit crop grown in the tropics and subtropics around the world including the Caribbean region. Anthracnose, caused by Colletotrichum gloeosporioides Penz., is considered the most important disease of mango in the humid tropics. Randomly amplified polymorphic DNA (RAPD) analyses, pathogenicity tests on inflorescences and detached leaves and fruits, susceptibility to benomyl, and pectic zymogram analysis were used to examine diversity among isolates of the pathogen from naturally infected leaves, peduncles, flowers, and immature, green and mature fruits. Although considerable genetic diversity was found, cluster analysis of the pathogenicity and RAPD data indicated several groups of isolates. Based on spore shape, one group might be classified as C. acutatum and not C. gloeosporioides. Isolates of the "C. acutatum" group tended to be slightly more virulent on inflorescences and less virulent on leaves and mature fruits. Such distinctions among Colletotrichum isolates from mango might be significant with respect to anthracnose control. The diversity of Colletotrichum associated with anthracnose of mango in Florida may help to explain why some mango cultivars with reported resistance to anthracnose elsewhere are susceptible in Florida