Identification and Biological Characteristics of Pathogen Causing Fusarium Wilt of Chinese Water Chestnut in Guangdong

【Objective】Fusarium wilt is prevalent in Chinese water chestnut producing regions of Guangdong Province, severely impacting crop yields. Identifying the pathogen and analyzing its biological characteristics is of significant importance for the effective management of the disease.【Method】Diseased samples were collected from Lechang, Shaoguan, between 2022 and 2024. Strains were isolated using the tissue isolation method. Their taxonomic status was determined based on pathogenicity, morphological characteristics and molecular biological features. The effects of temperature, pH, light, carbon and nitrogen source on the pathogens were measured by mycelium growth method.【Result】34 Fusarium spp. isolates with similar morphological characteristics were obtained. The colony was white on PDA medium. Conidiogenous cells were phialidic, 8.46~55.65 μm in length. Microconidia were abundant, oval or spindle-shaped, 4.22~12.65 μm × 2.24~3.82 μm, and borne false heads from phialides. Macroconidia were falcate, slightly curved, tapering apically with 3 to 5 septa, and 18.24~36.40 μm×2.92~4.50 μm. Chlamydospores were spherical, 7.85~12.32 μm in diameter. Pot experiments confirmed their pathogenicity to Chinese water chestnut. The phylogenetic trees constructed using combined sequences of the EF-1α, RPB2 and TUB revealed the pathogens clustered with Fusarium commune strains and distinctly differentiated from F. oxysporum. Specific primers amplification further confirmed the pathogens belonged to F. commune. The suitable temperature for mycelium growth of F. commune was 26~30℃, and the suitable pH was 7~8. Carbon source maltose, organic nitrogen source beef extract powder, yeast extract and tryptone were beneficial to mycelium growth, colony diameters reached approximately 60 mm after 120 h incubation at 28℃ in dark.【Conclusion】The study identified F. commune as the causative agent of Chinese water chestnut wilt in Guangdong, providing critical insights for disease control strategies.