Diversity and pathogenicity of Colletotrichum species causing strawberry anthracnose in Taiwan and description of a new species, Colletotrichum miaoliense sp. nov.

Strawberry is a small fruit crop with high economic value. Anthracnose caused by Colletotrichum spp. poses a serious threat to strawberry production, particularly in warm and humid climates, but knowledge of pathogen populations in tropical and subtropical regions is limited. To investigate the diversity of infectious agents causing strawberry anthracnose in Taiwan, a disease survey was conducted from 2010 to 2018, and Colletotrichum spp. were identified through morphological characterization and multilocus phylogenetic analysis with internal transcribed spacer, glyceraldehyde 3-phosphate dehydrogenase, chitin synthase, actin, beta-tubulin, calmodulin, and the intergenic region between Apn2 and MAT1-2-1 (ApMAT). Among 52 isolates collected from 24 farms/nurseries in Taiwan, a new species, Colletotrichum miaoliense sp. nov. (6% of all isolates), a species not previously known to be associated with strawberry, Colletotrichum karstii (6%), and three known species, Colletotrichum siamense (75%), Colletotrichum fructicola (11%), and Colletotrichum boninense (2%), were identified. The predominant species C. siamense and C. fructicola exhibited higher mycelial growth rates on potato dextrose agar and caused larger lesions on wounded and non-wounded detached strawberry leaves. Colletotrichum boninense, C. karstii, and C. miaoliense only caused lesions on wounded leaves. Understanding the composition and biology of the pathogen population will help in disease management and resistance breeding.