Isolates of Colletotrichum musae from four banana (Musa spp.) cultivars 'Comprida', 'Maçã', 'Pacovan' and 'Prata' were studied in relation to morphological aspects of conidia, cultural characteristics, diameter of colony on PDA medium, and conidia germination in sterile water and potato dextrose agar (PDA). Also observed was the effect of the carbon/nitrogen ratio on growth, sporulation, and dry weight of mycelial mass, under alternating light at 25 ºC. To study the effect of the C/N ratio, carbon sources (dextrose, sucrose and sorbitol) and nitrogen sources (asparagin, peptone and potassium nitrate) were combined in a proportion of 10:1 (10 g of C for 1 g of N). The results showed hyaline conidia with form and size characteristics of C. musae, which ranged within the limits established for the species. The isolates from 'Comprida' banana presented the shortest length in relation to the others. Conidia germination occurred after 8 h of incubation, and isolates varied in relation to percentage of germinated conidia. All isolates formed appressoria but they varied in the amount produced. In general, the cultural characteristics of the isolates on PDA showed variation in color and diameter of colonies. In relation to to effect of the C/N interactions, statistical analysis revealed significant variation among isolates, as well as independent factors, which effected mycelial growth, conidial production and the dry weight of the mycelial mass. All combinations of carbon involving peptone as the nitrogen source were favorable to the three physiological processes. Nevertheless, in each process observed, significant differences were found among the isolates of C. musae.
