Diversity of Fungi in the Cankered Tissues in Apple and Pear Trees

Tree canker, characterized by ulcerative lesions on stems and branches that lead to bark cracking, peeling, and decline in tree vigor, is a major disease of apple and pear orchards in Korea. However, information on the diversity of canker-associated fungi remains limited. In this study, cankered stems and branches were collected from apple and pear orchards across Korea during the spring and summer season of 2025. Fungi were isolated from symptomatic tissues and identified using morphological and molecular phylogenetic analyses. A total of 82 isolates (16 genera, 26 species) were obtained from two pear orchards, and 163 isolates (17 genera, 30 species) were obtained from four apple orchards. Altogether, 219 isolates representing 20 genera and 44 species were identified. The most dominant pathogenic species in both apple and pear orchards were Diaporthe eres and Botryosphaeria dothidea. In addition, Aureobasidium pullulans, a species widely used as a biological control agent, was also dominant, while the saprophytic genus Alternaria was frequently isolated. Other pathogenic fungi identified included Cytospora ceratospaerma, C. mali, Diaporthe amygdali, D. fukushii, D. sackstonii, Diaporthe sp. voucher DUCC15258, Didymosphaeria variabile, and Paraphoma chrysanthemicola. These findings provide comprehensive insights into the diversity of canker-associated fungi in Korea and broaden the known pathogen spectrum. Our results offer valuable baseline data for improving disease diagnosis, predicting pathogen emergence, and establishing effective management strategies for canker in apple and pear orchards.