Identification and Biological Properties of Leaf Spot Pathogen on Rhododendron fortunei in Jingning

In 2017 and 2018, Rhododendron fortunei leaves infected by leaf spot disease were collected in Jingning, Zhejiang province for pathogen research. 9 strains were obtained and DJ-1 was isolated by single spore isolation which was verified by card of Koch's postulation disease test as pathogenic bacteria. It was idendified Phomopsis asparagi by morphology and molecular biology techniques. Experiments showed that different culture condition had different mycelium growth and conidium quantity. It demonstrated that the PDA was the best for mycelium growth, mannitol and glycine for carbon and nitrogen source. The best medium for conidium quantity was PDA and PSA medium with the best carbon and nitrogen source of glucose and fructose, and glycine. The optimal pH for mycelium growth and conidium quantity was 8 and that of light was12 hours of illumination + 12 hours of dark. The experiment showed that the lethal temperature was 55℃ for 10 minutes for conidium, and 60℃ for 10 minutes for the mycelium.