Fungal Species Isolated from Canker and Canker-like Symptoms in Apple Seedlings 

Canker is a major disease in apple and pear orchards in Korea. It is characterized by necrotic lesions on stems and branches, bark cracking and peeling, and reduced tree vigor. However, little is known about when canker-associated pathogens first become established in apple trees. Thus, in this study, we invesigated branches showing canker and canker-like symptoms in 2025 from 21 apple seedlings of the cultivar ‘Fuji’ (Myanmar lineage) cultivated in Gyeongsan, Gyeongsangbuk-do, Korea. Fungi were isolated from symptomatic tissues and identified based on morphological characteristics and molecular phylogenetic analyses. A total of 87 isolates representing 16 species in 12 genera were identified. The dominant pathogenic fungi were Diaporthe eres and Botryosphaeria dothidea Which have been recognized as the major canker pathogens. Alternaria, a saprophytic fungus, was also frequently isolated. In addition, Diaporthe phaseolorum, Stagonosporopsis cucurbitacearum, and Botryosphaeria wangensis, which have not been reported as pathogens on apple trees were also recovered. These results suggest that diverse pathogenic or potentially pathogenic fungi associated with canker could be present at the young seedling stage of apple. Therefore, for the control of canker on apple tree, the production of pathogenic fungus free seedlings in nursury is likely crutial as a  diseae preventive method. Toclarify this assuption, broad survey of fungi on seedlings is required.