First Report of Alternaria alternata Causing Leaf Spot on Yucca gloriosa in Korea

First Report of Alternaria alternata Causing Leaf Spot on Yucca gloriosa in Korea

Dongwook Kim1, Sun Choi1, Sung Gwang Lee2, Taeho Kim1, and Sook-Young Park1 ,2, 3*

1 Dept. of Agricultural Life Science, Sunchon National University, Suncheon, Republic of Korea

2 Dept. of Plant Medicine, Sunchon National University, Suncheon, Republic of Korea

3Interdisciplinary Program in IT-Bio Convergence System (BK21 plus), Sunchon National University, Suncheon, Republic of Korea

*Email: spark@scnu.ac.kr

In April 2025, leaf spot symptoms were observed on Spanish yucca (Yucca gloriosa) at Suncheon Bay National Garden in Korea. Approximately 20–30% of the 50 surveyed plants showed brown leaf spot lesions. Symptomatic tissues were surface-sterilized and plated on 1.5% water agar, and the resulting fungi were transferred to potato dextrose agar (PDA). Three isolates (SYP-1777 to SYP-1779) were obtained through single-spore isolation. Colonies were dark brown at the center and grayish brown toward the margins. Conidia were light brown, ellipsoid to obclavate, with 1–6 transverse and 0–3 longitudinal septa. Molecular identification based on seven gene regions (ITS, gapdh, tef1, rpb2, Alt a1, endoPG, and OPA10-2) and phylogenetic analysis confirmed the isolates as Alternaria alternata. Pathogenicity tests using isolate SYP-1777 on wounded yucca leaves produced symptoms similar to those observed in the field, and the pathogen was successfully re-isolated, fulfilling Koch’s postulates. To our knowledge, this is the first report of A. alternata causing leaf spot on Y. gloriosa in Korea.