First Report of Leaf Blight Caused by Didymella segeticola on Slender Angelica (Conioselinum tenuissimum) in Korea

In 2014, a previously unreported leaf blight was observed on the medicinal plant slender angelica (Conioselinum tenuissimum) in Jecheon, Korea. Symptoms began as a marginal blight that progressed to necrosis of the leaf tips, with numerous pycnidia forming on lesions. The fungus isolated from the lesions produced hyaline, aseptate, ellipsoidal to ovoid conidia (4.95±0.79 × 1.94±0.29 μm) and was preliminarily identified as a Phoma-like species based on its morphology. For definitive identification, a multi-locus phylogenetic analysis of the internal transcribed spacer regions and intervening 5.8S nrDNA region, large subunit rRNA gene, RNA polymerase II second largest subunit gene, and beta-tubulin gene regions identified the causal agent as Didymella segeticola. Pathogenicity was confirmed by fulfilling Koch’s postulates; healthy plants inoculated with a conidial suspension developed typical symptoms, and the same pathogen was re-isolated. This is the first report of D. segeticola causing leaf blight on C. tenuissimum in Korea.