Characterization and pathogenicity of Colletotrichum spp. causing citrus anthracnose in Tunisia

In the winter and spring of 2014-2015, typical anthracnose symptoms were detected on different citrus varieties in Cap-Bon and Morneg-Tunis regions of Northern Tunisia. Surveys were conducted to determine the casual agents of these symptoms. A total of seven monosporic isolates were obtained from dark lesions on fruits, flowers, leaves and twigs of citrus from six orchards. One Colletotrichum karstii (from the C. boninense species complex) and six C. gloeosporioides isolates were identified through morphological analysis and sequencing of their ITS rDNA sequences. Pathogenicity tests with the seven isolates were performed on symptomless, detached citrus fruits (Valencia orange and Eureka lemon). All tested isolates caused anthracnose lesions after 1 week of incubation. Koch's postulates were fulfilled by re-isolation of pathogens from the inoculated fruits. This report elucidates the diversity of anthracnose pathogens in Tunisia. This is the first report of C. karstii from citrus in Tunisia.