[Identification, biological characteristics, and control of pathogen causing southern blight of Pinellia ternata]

In summer in 2020, Pinellia ternata in many planting areas in Hubei suffered from serious southern blight, as manifested by the yellowing and wilted leaves and rotten tubers. This study aims to identify the pathogen, clarify the biological characteristics of the pathogen, and screen fungicides. To be specific, the pathogen was isolated, purified, and identified, and the pathogenicity was detected according to the Koch's postulates. Moreover, the biological characteristics of the pathogen were analyzed. Furthermore, PDA plates and seedlings were used to determine the most effective fungicides. The results showed that the mycelia of the pathogen were white and villous with silk luster, which produced a large number of white to black brown sclerotia. The pathogen was identified as Athelia rolfsii by morphological observation and molecular identification based on LSU and TEF gene sequences. The optimum growth conditions for A. rolfsii were 30 ℃ and pH 5-8, and the optimum conditions for the germination of sclerotia were 25 ℃ and pH 7-9. Bacillus subtilis, difenoconazole, and flusilazole were identified as effective fungicides with PDA, and their half maximal effective concentration(EC_(50)) was all less than 5 mg·L~(-1). The effective fungicides screened with the seedlings were hymexazol and difenoconazole. Based on the screening experiments, difenoconazole can be used as the main agent for the prevention and treatment of southern blight.