First Report of Leaf Spot on Camellia japonica Caused by Alternaria alternata in Korea

In May 2023, leaf spot disease was observed on the leaves of camellia trees (Camellia japonica) in Suncheonsi, Jeonnam Province. To identify the fungal species responsible for the disease, we isolated samples from the diseased leaves. Based on morphological characteristics and phylogenetic analysis, we identified the causal fungus of leaf spot disease as the ascomycete Alternaria alternata. Pathogenicity assays confirmed that the isolates were the causal agents of leaf spot disease, and the fungus was reisolated from the infected leaves, thus fulfilling Koch’s postulates. To our knowledge, this is the first report of A. alternata as the causal pathogen of leaf spot disease on C. japonica in Korea. Our results will contribute to the development of effective control strategies for this disease in the future.