Are microconidia infectious principles in Neonectria ditissima?

Comparative studies of different isolates of Neonectria ditissima obtained from canker lesions and rotten fruit showed that both five-septate macroconidia and aseptate microconidia were capable of germination by germ-tube formation, but that growth commenced earlier and proceeded faster from the former than the latter type of spore. Further, following wound inoculation of apple fruit with different numbers of conidia (50, 500 or 5000 per wound) the resulting rot lesions were always significantly larger with macroconidia than microconidia, and in both conidial types lesion size increased with higher inoculum loads. These data confirm that microconidia are capable of causing infections, but indicate that their contribution to the success of the pathogen in the field is probably negligible. [ABSTRACT FROM AUTHOR]