Characterization of Colletotrichum acutatum isolates causing anthracnose of strawberry in calabria

Strawberry (Fragaria x ananassa Duchesne) is a crop of major economic importance in the Lametia Terme plains (Calabria, southern Italy). Cold-stored and fresh strawberry plantlets are imported from Belarus, California, and Spain, and are transplanted from late September through early November. Fruits are harvested from January through early June. In the last 10 years, outbreaks of fruit anthracnose, commonly known as blackspot, have been observed after late spring rains. `Camarosa', the prevalent cultivar in this area, is moderately susceptible to this disease. A collection of 120 single-conidium strawberry isolates of Colletotrichum from Calabria and other regions of southern, central, and northern Italy were characterized by morphological and cultural traits, isozyme (ACP, ALADH, G sub(6)PD, EST, MDH, SOD, XDH and GPI) electrophoresis, RAPD analysis of DNA, with 16 decamer primers, and vegetative compatibility tests, with nitrate non-utilizing (nit) mutants. All isolates were identified as C. acutatum J.H. Simmonds (anamorph of Glomerella acutata Gueber & Correll) and showed very limited genetic diversity. Their isozyme and EAPD patterns were very similar or almost identical to the patterns of strawberry referenceisolates of C. acutatum from California and Spain. Moreover, all isolates, including reference-isolates from California and Spain, were assigned to a single vegetative compatibility group, with the only exception of 35 isolates that resulted to be self-incompatible. These results suggest that all isolates belong to a clonal population and that spread of C. acutatum has occurred between distant geographic areas via infected strawberry material, notwithstanding the fact that this fungus is a quarantine pathogen in the EPPO region.