First report of sudden wilt caused by Ceratocystis manginecans on ancient camphor trees ( Camphora officinarum ) in China

The camphor tree (Camphora officinarum Nees ex Wall) is a prominent and ecologically valuable evergreen broad-leaved species in China. Since November 2024, severe rapid wilting and complete tree death have been observed on ancient camphor trees in and around Guoqing Temple in Tiantai County, Zhejiang Province, China. Among the 69 ancient camphor trees surveyed, 13 (18.8%) displayed symptoms including leaf wilting, bark discoloration, and stem cankers. The disease severity was exceptionally high, as eight of the symptomatic trees had already died due to the infection. Symptom onset was frequently associated with pruning wounds, squirrels, or wood-boring insects. Symptomatic stem sections were collected to isolate potential pathogens. A Ceratocystis species was consistently recovered from the discolored stem tissues of all 13 symptomatic trees using carrot baits (Moller and de Vay 1968). Spore masses from perithecia on carrots were transferred to MYEA for single-spore isolation. Four representative isolates (TTGQS01 to TTGQS04) were obtained and deposited at the Forest Protection Laboratory, Zhejiang A&F University. Fungal colonies on MYEA were initially white, transitioning to greyish-green or brown with regular margins, and produced a banana-like odor. Perithecia were dark brown to black, globose (112.5 to 321.5 × 111.5 to 313.5 μm), with slender necks (312.5 to 798.5 μm long, 25.5 to 51.5 μm wide at the base, and 12.5 to 30.5 μm wide at the tip). Ascospores were hyaline, hat-shaped, measuring 4.5 to 5.5 × 3.0 to 3.5 μm. Two types of hyaline conidia were observed: cylindrical (18.5 to 28.5 × 4.0 to 4.5 μm) and barrel-shaped (8.5 to 12.5 × 4.0 to 4.5 μm). Aleurioconidia were not observed. The internal transcribed spacer (ITS) region, β-tubulin, and translation elongation factor 1-α (EF1-α) genes were amplified using primer pairs ITS1/ITS4, βt1a/βt1b, and EF1F/EF2R, respectively (van Wyk et al. 2009). BLAST searches of ITS sequences (GenBank Accession Nos. PX884520 to PX884523), β-tubulin (PZ490122 to PZ490125), and EF1-α (PZ485550, PZ480364, PZ493705, and PZ493706) revealed 99% to 100% identity to a reference isolate (CMW14797) from Mangifera indica in Brazil. Following the taxonomic framework of Harrington et al. (2024), a phylogenetic tree placed the pathogen within the C. manginecans complex (Lynn et al. 2025). To fulfill Koch's postulates, pathogenicity tests were conducted on 15 disease-free, 3-year-old camphor seedlings in a greenhouse (29 ± 5 ∘C, >80% RH). Ten seedlings were stem-wounded (0.4 cm cross-cut) using a sterile scalpel and inoculated with a 4-mm mycelial plug from a 5-day-old culture of isolate TTGQS01. Five mock-inoculated seedlings received sterile MYEA plugs. At one-week post-inoculation, early symptoms of longitudinal stem discoloration appeared on all fungus-inoculated plants. At 30 days, inoculated plants exhibited wilting and death, identical to field symptoms. Control plants remained healthy. The identical C. manginecans pathogen was re-isolated from 100% of the inoculated seedlings, but not from the controls. To our knowledge, this is the first report of C. manginecans causing wilt on Camphora officinarum globally. C. manginecans has been increasingly reported on woody hosts across multiple families, including Albizia lebbeck (Razzaq et al. 2020) and Dalbergia sissoo (Al Adawi et al. 2013). This aggressive disease threatens the cultural and ecological heritage of ancient camphor resources and necessitates immediate integrated management strategies focusing on wound prevention and protection.