The biology of Colletotrichum musae (Berk. et Curt.) Arx and its relation for control of banana anthracnose
Anthracnose caused by #Colletotrichum musae# is the main postharvest disease affecting the quality of exported bananas from the French Caribbean islands. The postharvest chemical control has been hampered by the emergence of fungicide resistance to thiabendazole and by the poor efficacy of these treatments in some areas, due to the greater susceptibility of the fruits to this disease in these areas. Epidemiological studies have been carried out to develop new control strategies. A waterbome spore trap has been set under banana bunches from flowering to harvest, to collect all #Colletomchum conidia# dispersed in weekly rainwater runoff from the whole banana bunch. Most conidia were trapped from 7-35 days after flowering, with a strong decline until harvest. The quantity of conidia collected varied according to climatic conditions during this critical period. when the flower parts and the last bunch bract were removed, considerable reduction of conidia collected in the spore traps was achieved. Isolation of #Colletotricum# species present on the flower parts of 100 bunches was carried out on a selective medium from flowering to harvest. The patterm of #Colletotrichum# isolation was the same as conidia trapping, #C.musae# was associated with other #Colletotrichum# species distinguishable by their morphological characteristics. These species were not pathogenic. Covering the bunches with a plastic sleeve had no effect on the quantity of #Colletotrichum# colonies isolated from flower parts, from flowering to harvest. Nevertheless, the quantity of anthracnose lesions developing on ripe fruits was considerably less important on sleeved than on unsleeved bunches. Consequences in terms of improvement of anthracnose control are discussed.