Snake Plant (Dracaena trifasciata) is a hardy, low-maintenance ornamental plant commonly grown in indoor and outdoor landscapes across Hawaii. In January 2025, plants exhibiting circular, water-soaked foliar lesions with concentric rings and abundant black acervuli were observed in an outdoor landscape bed in Honolulu, Oahu. Lesions occupied 10 to 50% of leaf surfaces and affected approximately 70% of plants within the bed. Six symptomatic leaves were collected for diagnosis. Tissue sections (5mm 2 ) from lesion margins were excised, surface sterilized in 10% NaOCl for 30 s, washed twice in sterile water, and plated on potato dextrose agar. Plates were incubated at 22ºC under a 12-h light/dark cycles for 7 days. Three representative isolates (M25B06A, M25B06B, and M25B06C) were obtained through single-spore isolation. M25B06A formed a circular, orange-brown colony with white margins and sparse aerial mycelia. M25B06B and M25B06C formed circular, cottony, grayish-white colonies with abundant olivaceous to black acervuli. Reverse colony colors ranged from grayish-orange to brown with dark gray centers. Conidia were hyaline, single-celled, cylindrical to slightly clavate, and measured 16.98 ± 2.03 µm × 6.42 ± 0.62 (n=50). Genomic DNA was extracted using DNeasy Plant Mini Kit TM (Qiagen, Germany) and used as template in PCR reactions with GoTaq® Hot Start Green Master Mix (Promega, USA). The internal transcribed spacer (ITS) region was amplified using primers ITS1-F/ITS4 (Gardes and Bruns 1993), β-tubulin (TUB) using primers T1/BT2B (Glass and Donaldson 1995), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) using primers GDF/GDR (Templeton et al. 1992). Amplicons were purified with ExoSAP-IT® (ThermoFisher Scientific, USA) prior to DNA Sanger Sequencing. Sequence analysis using Geneious Prime® 2025.1.2 software and BLAST searches of each locus from the three isolates resulted in 99 to 100% sequence identity to multiple Colletotrichum sansevieriae isolates. Sequences were deposited in GenBank (ITS: PV706934, PV706935, PV706936; GAPDH: PV730292, PV730293, PV730294; TUB: PV730295, PV730296, PV730297). Multilocus phylogenetic analysis using concatenated ITS, GAPDH, and TUB sequences was conducted using MEGA 12 software. The isolates clustered closely with C. sansevieriae isolate FPH2021-5 from Ohio (Valero David et al. 2023) and formed a well-supported clade that is distinct from other Colletotrichum species. Koch’s postulates were fulfilled on healthy D. trifasciata ‘Moonshine’. Three 7-inch detached leaves were wounded using a sterile syringe needle and inoculated with 20 µL of 1 × 10 5 conidia/mL suspension of M25B06C on one side of the leaf, and sterile water on the other. Leaves were incubated in a moist chamber at 25ºC with a 12-h light/dark photoperiod for 14 days. The assay was conducted twice. Water-soaked lesions developed on inoculated wounds by 3 days post-inoculation (DPI), followed by formation of concentric rings and black acervuli by 9 DPI. By 14 DPI, lesions had coalesced and blighting was evident. No symptoms developed in the controls. C. sansevieriae was reisolated from symptomatic tissue and matched the morphocultural characteristics of the original isolate. To our knowledge, this is the first formal documentation confirming C. sansevieriae as the causal agent of snake plant anthracnose in Hawaii, based on morphological characterization, molecular identification, and fulfillment of Koch’s postulates.
Caligayahan et al. (Sat,) studied this question.