| 【Objective】Leaf spot is an important factor restricting the gladiolus industry in Taishan City, Guangdong Province. To provide references for controlling the disease, the pathogen was classified and identified, and the biological characteristics and fungicide sensitivity were studied.【Method】The taxonomic status of pathogen was identified based on pathogenicity determination, morphological characteristics and rDNA-ITS sequence analysis. The effects of temperature, pH, light, carbon source, nitrogen source and fungicide on the pathogen were measured by mycelium growth method and microscopic examination.【Result】Four isolates were purified and obtained from the diseased samples with the same morphological characteristics. The results of pathogenicity determination showed that the symptoms produced by artificial inoculation were consistent with those observed in the field. Conidiophores of the pathogen were brown, mostly solitary, septate, and knee-curved at the top, with the size of 51.0 - 80.0 m×4.0 - 7.6 m. Conidia were brown, arched, four cells, wide in the middle and narrow at both ends, and curved to one side, with the size of 23.5 - 32.0 m×11.5 - 16.0 m. Phylogenetic analysis based on the rDNA-ITS sequences of the pathogen showed that the pathogen and Curvularia gladioli clustered together to form distinct branches. The pathogen was identified as C. gladioli Boerema & Hamers by morphological characteristics and rDNA-ITS sequence analysis. The optimal temperatures and pH ranges for mycelial growth and sporulation of the pathogen were 26 - 30 ℃ and 5.0 - 7.0, respectively. Light promoted the growth of mycelia and darkness promoted the sporulation. Carbon source xylose, glucose and organic nitrogen source beef extract were beneficial to the growth and spore production. Prochloraz and mancozeb had strongest inhibitory effect on mycelial growth of the pathogen, and EC50 were 1.23 g/mL and 2.81 g/mL, respectively.【Conclusion】The pathogen of Taishan gladiolus leaf spot disease was identified as C. gladioli, which was sensitive to prochloraz and mancozeb. And the optimal temperatures and pH ranges for the growth of the pathogen were 26 - 30 ℃ and pH 5.0 - 7.0, respectively. |
