Characterization of the Colletotrichum gloeosporioides species complex causing grape ripe rot in Nagano Prefecture, Japan

Abstract

Isolates of the Colletotrichum gloeosporioides species complex from grape ripe rot in Nagano Prefecture, Japan in 2016–2017 were identified and their morphology, virulence, and fungicide sensitivity clarified. Based on phylogenetic analysis of the ApMat locus, 80 isolates were identified as belonging to four species, C. perseae (17.5%), C. viniferum (8.8%), C. fructicola (7.5%), and C. gloeosporioides sensu stricto (2.5%) and another species designated Clade V (63.8%). Clade V was the most important pathogen in Nagano Prefecture because of its predominance and high virulence. Colletotrichum perseae and C. fructicola both had a sexual stage and were often found to be resistance to QoI fungicides; they were dominant in the northern region of Nagano Prefecture in 2016. These four species and Clade V can be distinguished by the growth rate of their colonies and morphology of their conidia and ascospores. The results of this study suggest that identification of dominant species in each field is necessary to determine the most suitable fungicide application for disease control.