First Report of Anthracnose Caused by <i>Colletotrichum fioriniae</i> on Persimmon in Korea

Anthracnose caused by Colletotrichum spp. is a major disease of persimmon (Diospyros kaki). In September 2024, typical anthracnose symptoms were observed on persimmon trees in a commercial orchard in Suncheon, Jeonnam, Korea (35°00′03.9″N, 127°30′22.0″E). Disease incidence reached approximately 30%. Initial symptoms appeared as water-soaked lesions on leaves, followed by sunken necrotic lesions on shoots and fruits. Symptomatic tissues were surface-sterilized and plated onto potato dextrose agar (PDA). Single-spore isolates were obtained and cultured on PDA at 25°C. Colonies produced cottony mycelia with pale orange conidial masses. Conidia were hyaline, fusiform to cylindrical, and measured 9.5–16.6 × 3.1–5.1 μm (n = 100), consistent with descriptions of C. fioriniae (Damm et al. 2021). Appressoria were dark brown and ovoid to irregular. Representative isolates (APS-121, APS-122, APS-123, and APS-124) were selected for molecular identification. Multilocus sequence analyses were performed using ITS, ACT, CHS-1, GAPDH, HIS3, and TUB2 gene regions. Sequences were deposited in GenBank under accession numbers PX763191–PX763194 (ITS), PX830444–PX830447 (ACT), PX830448–PX830451 (CHS-1), PX830452–PX830455 (GAPDH), PX830456–PX830459 (HIS3), and PX830460–PX830463 (TUB2). BLASTn analysis showed 99–100% identity with reference sequences of C. fioriniae. A maximum-likelihood phylogenetic analysis based on concatenated sequences (ITS, ACT, CHS-1, GAPDH, HIS3, and TUB2; 3,245 bp total) confirmed that all isolates clustered with reference strains of C. fioriniae with high bootstrap support. The tree was constructed using the maximum-likelihood method in MEGA X with 1,000 bootstrap replicates. C. horii CBS 1180.1 was used as an outgroup. Representative isolates were deposited in the Korean Agricultural Culture Collection (KACC 411311–411314). Pathogenicity tests were conducted by inoculating wounded leaves, shoots, and fruits of persimmon cultivar ‘Buyu’ with a conidial suspension (1 × 10⁶ conidia/ml). Inoculated tissues were maintained at 25°C under high humidity. Typical anthracnose symptoms developed within 5–7 days. The pathogen was re-isolated and confirmed as C. fioriniae based on morphological and molecular characteristics, fulfilling Koch’s postulates. Control tissues inoculated with sterile water remained symptomless. C. fioriniae has previously been reported causing anthracnose on persimmon in China (Fan and Ren 2024) and fruit rot on litchi (Ling and Peng 2021). No previous reports of C. fioriniae on persimmon in Korea were found in the APS database or other scientific literature. To our knowledge, this is the first report of anthracnose caused by C. fioriniae on persimmon in Korea.