Etiological Identification And Pathogenicity Test Of Leaf Blight Of Cercis Chinensis

Cercis chinensis, belonging to legume, is a kind of famous ornamental arbor tree, with strong adaptability and a wide distribution in ecosystem, and cultivated world-wide. In addition to virescence and gardening, its application also covers the areas of medicine, agrochemical, chemical engineering, architecture, etc. Cercis chinensis leaf blight disease is a new disease that infects and causes harm to Cercis chinensis, about which there are no researches internationally thus far.Occurrence and development of Cercis chinensis leaf blight disease reduce the value of Cercis chinensis for appreciation. In the year 2005-2006, we did an investigation on the Cercis chinensis in YangLing and some other districts neighboring: Zhou Zhi and Li Quan county. A large number of Cercis chinensis plants in NWSUA&F and other areas in Yangling were found diseased, some of them even have died because of this disease. In order to find the ways to control this disease in a scientic and effective way, we carried this research on the Cercis chinensis leaf blight disease. Through research, the main 4 results are as follows.1. We successfully isolated and identified the pathogeny from diseased Cercis chinensis,which were inoculated back to healthy plants, and they expressed the same symptom. By identification of their pathogenicity and morphology of 17 isolated strains of Cercis chinensis leaf blight disease, they were confirmed Pestalotiopsis of W1 group and Phoma cercidicola .Henn of B1 group. This pathogenicity can grow in 10-35℃,PH5-10, and the most suitable temperature is 20-25℃, PH is 6. The most suitable media are Cercis chinensis juice and PDA. We also carried attempt to eradicate the dormancy of Cercis chinensis seeds, finding that those treated with sulphate acid for 10-30 min may germinate 7 days - 14 days ahead than normal, and the rate of germinating and seedlings emergence also improve 5-30 percent more than normal.2. We designed three methods to inoculate to the representative strain of W1 and B1 group: root cutting inoculation, inoculation in the soil, and dipping roots inoculation, with strains after isolation and purification, finding that the pathogencity of W1 group is stronger than that of B1, and dipping roots vaccination achieve the best result of morbidity.3. Through the investigation in field, the results showed that the incidence of this disease appears in late April and at the beginning of the May, reach the first peak after a month, but nearly stopped in June and July. The second peak appears between August and September accompany with the decreasing of temperature and increasing of rainfall, then the disease guadually stopped.4. The result showed that there is some relation to Cercis chinensis leaf blight disease with temperature, humidity, and plant density. In this relation, Low temperature, large humidity and high plant density are all advantage to Cercis chinensis leaf blight disease's occurrence and development.