Colletotrichum species associated with loquat anthracnose in Kagawa and Tokushima prefectures, Japan

Abstract Anthracnose caused by Colletotrichum species is one of the serious diseases of loquat, but diversification of the species of Colletotrichum associated with loquat in Japan has not been adequately surveyed. In this study, 46 isolates were isolated from diseased leaves and fruits of loquat in Kagawa and Tokushima prefectures in 2017 and 2018. Using a combination of morphological features and molecular approaches, seven Colletotrichum species were identified: C. fioriniae, C. nymphaeae, C. karsti, C. aenigma, C. fructicola, C. gloeosporioides s. s., and C. siamense. The most prevalent species was C. karsti followed by C. fioriniae and C. gloeosporioides s. s., accounting for 43.5, 21.7, and 13.0%, respectively. All identified species were confirmed to be the causal agents of loquat anthracnose by applying Koch’s postulates. Moreover, potential cross-infection from loquat to kiwifruit, satsuma mandarin, persimmon, and peach was found, in which loquat isolates of C. fioriniae, C. fructicola, and C. siamense caused symptoms on all the tested plants. This report is the first on C. karsti and C. aenigma associated with loquat anthracnose and the first record of C. fructicola and C. gloeosporioides s. s. in Japan, providing crucial information for epidemiology.