Isolation and Identification of Pathogen of Staphylea bumalda Leaf Blight and Test of Fungicide Screening

【Objective】A new disease causing Staphylea bumalda leaf blight was observed in the experimental garden in Xiaogan Academy of Agricultural Sciences and its pathogen and fungicides were identified. 【Method】 Preliminary research was conducted through the isolation and culture of pathogen, pathogenicity determination， morphological observation，molecular biological identification, fatty acid composition analysis and screening of indoor fungicides.【Result】The disease was caused by Alternaria alternate fungus. The bacterial colony of the pathogen was steel-gray，and the conidia were connected in series to form a chain with a size of 3.5-15.8 μm×7.6-46.5 μm with 2-10 transverse septa and 0-3 longitudinal and oblique septa. In addition, it was observed that the symptoms of leaves were similar to those of diseased plants in the field 14 days after inoculation of pathogen. The pathogenic fungi were re-isolated from the diseased leaves after inoculation. Molecular identification results showed that the isolated pathogens were consistent with inoculated fungus. Among the tested fungicides, Amidazole amidazine had the best bacteriostatic effect,with EC50 being the lowest at 0.4004 (g/mL). After being diluted 5 000 times on the basis of recommended concentration indicated on fungicide packaging, it still had bacteriostatic effect with a bacteriostatic rate is 42.8%. The effects of Enoyl imidamine, Fu Fu zine and Tricyclic fluoryclazole were inferior to that of Amidazole amidazine, with an EC50 of 1.461 9 μg/mL, 1.756 2 μg/mL, 6.055 9 μg/mL, respectively.【Conclusion】For the first time, the pathogen causing S. bumalda leaf blight was found to be A. Alternate fungi. Among the four tested fungicides, Amidazole amidazine had the best bacteriostatic effect.