First Report of Colletotrichum tabacum Causing Anthracnose on Water Speedwell (Veronica anagallis-aquatica) Plants in Korea

Anthracnose symptoms were observed on water speedwell (Veronica anagallis-aquatica) plants in Gangwon and Gyeonggi provinces, Korea, during field surveys conducted in May 2024 and 2025, affecting approximately 80% of the surveyed plants. The typical symptoms exhibited dark brown to black necrotic lesions that developed on the leaves and stems. A fungus was isolated from the collected diseased samples, and two representative isolates (KACC 410829 and KACC 411071) were identified as Colletotrichum tabacum on the basis of morphology and multi-locus phylogenetic analyses of ITS, GAPDH, CHS-1, HIS3, and ACT sequences. Pathogenicity tests reproduced the symptoms on healthy leaves, and the same fungus was reisolated, fulfilling Koch's postulates. This is the first report of C. tabacum infecting water speedwell plants, expanding its known host range and highlighting its potential threat to aquatic and wetland vegetation in Korea.