Preliminary Studies on the Biology of «Phaeoacremonium»

Abstract

Comparative microflora studies of one-year-old pruned and unpruned canes carried out during dormancy period over three consecutive years showed that Phaeoacremonium chlamydosporum was more frequently isolated from pruned than unpruned canes, while Phaeoacremonium aleophilum was found as much in pruned as in unpruned canes. Inoculations of pruning wounds made in two consecutive winters by suspensions of conidia of P. chlamydosporum and P. aleophilum showed that both fungi were able to invade through wounds during winter. Infections varied with pruning date and age of pruning wound, but were more serious and of longer duration with early pruning (December, January). Trapping studies showed that spores of P. chlamydosporum were captured throughout the whole year, while spores of P. aleophilum were mostly trapped during the vegetative period. Microscopic examination of adhesive tape applied to without bark zones of the canes showed the presence of conidia of P. aleophilum. From these studies, it emerged that only P. chlamydosporum is able to contaminate pruning wounds during winter. P. chlamydosporum and P. aleophilum may be propagated by infected canes in the nursery. They can be considered airborne fungi during a period of their biological cycle.