Objective To Identify the pathogen causing leaf spot of Cinnamomum camphora in Wanzhou District, clarify the characteristics of mycelium growth, and select fungicides that effectively inhibit the pathogen for providing a theoretical basis for prevention and control of leaf spot disease.

Method The pathogen was isolated and purified by the tissue separation method, and the pathogenicity was tested by Koch's method. Pathogens were identified based on morphological characteristics and multilogues phylogenetic analysis combined with ITS, tub2, GAPDH, and ApMat genes; The hyphae growth rate method was used to study the characteristics of mycelium growth, and the fungicides were selected.

Result The isolated strains were grayish and the edge was white when the mycelium was cultured on PDA medium for 3 days. The orange conidiomata appeared in the late. The conidia were long oval, blunt round at both ends, transparent and colorless were independent cells. The measured spore size was (9.8～18.6) μm × (4.2～6.0) μm; Pathogenicity of strain ZT-1 was tested by two methods, both of which could cause the leaf spot disease of C. camphora leaves; The representative strains ZT-1 and ZT-5 clustered with Colletotrichum gloeosporioides, and the reliability was 100%; The optimum growth temperature of the pathogen was 28 ℃; The optimum pH value was 6.0; Potato Dextrose Agar medium was beneficial to mycelial growth; The optimum carbon and nitrogen sources were glucose and glycine; The optimum lighting condition was total darkness. Among the chemical and biological fungicides, 15% triadimefon WP and 1% osthol EW were highly toxic and the inhibition effect of C. gloeosporioides was obvious. Their EC₅₀ values were less than 10 μg·mL⁻¹.

Conclusion C. gloeosporioides is the pathogen causing anthracnose on C. camphora in Wanzhou District and 15% triadimefon WP can be used as a fungicide for control.