Colletotrichum acutatum complex causing anthracnose on peach in Brazil

Anthracnose, caused by Colletotrichum spp., has caused damage and great losses in peach orchards in two Brazilian states, Santa Catarina (SC) and Sao Paulo (SP). There is limited information on the characterization of Colletotrichum spp. from those locations. In this study we characterized Colletotrichum spp. isolated from peach fruit from SC and SP, and compared them to a reference isolate of Colletotrichum gloeosporioides, using molecular and traditional tools. Molecular analysis revealed that all isolates (7) belong to C. acutatum species complex (Cac) and three of them are C. nymphaeae. Most of the isolates showed distinct characteristics among them for most of the variables assessed using traditional methods. The optimum temperature for mycelial growth ranged from 24 to 26 degrees C, for conidial germination it ranged from 22.7 to 24.6 degrees C, and for germ tube length the temperature ranged from 21.3 to 27.3 degrees C. Disease severity caused by the Cac isolates was similar when compared wounded and nonwounded fruits. The PrpCnSP13-19 isolate was the most aggressive. More severe anthracnose symptoms were observed in fruits inoculated and maintained at simulated temperatures of Sao Paulo state when compared to fruits inoculated and maintained at simulated temperatures of the states of Parana, Santa Catarina and Rio Grande do Sul. Our results suggest that there are different strains of Cac, with different level of aggressiveness and optimum temperatures for disease development.