| Because of Cornus controversum Hemsl.’s wide adaptability and fast growing, it is widely planted as an important greening species. In recent years, discovered C. controversum leaf blight generally occurred in Shenyang, causes leaves margins withered or whole leaves withered. The pathogens is different from the pathogens of previous studies and it has yet to see its research reports. The experiment on hazard symptoms of C. controversum leaf blight, occurrence and development rules, identification of pathogen fungus, the biological characteristics of pathogen fungus and Fungicide screening, toxicity measurement are studied, It provides a theoretical foundation for future in-depth study of the disease and effective control.1.By taking the method of general investigation to conduct a comprehensive survey within Shenyang multiple locations. Investigate the harm of diseases and occurrence characteristics, use classification counting method comprehensive statistical incidence and disease index. The results show that the disease is widespread in Shenyang, Shen he is a serious disease, the rate of diseased plant is 22.06%, disease index is 10.78; In other parts of the rate of diseased plant is 8.33%～15.38%, disease index is 5.83～8.47, The extent of the occurrence of disease is related with tree age, canopy density, environmental sanitation and vertical distribution part. With the age and canopy density increases, the more serious the occurrence of disease. The worse environmental sanitation is, the more serious the occurrence of disease. And the lower range of the incidence and disease index higher than that on the medium and upper.2.By taking the method of fixed observations for disease symptom. The lesion is irregular in shape and the color is light brown during early stage. Sometimes there is a banded region between leaf spot and the healthy. Serious illness development period during late July to mid-August. Spots link to form large spots and extend to leaf base. A large area of leaf wilt appear in late September, even early deciduous.3. By the combining identification method of traditional morphological and molecular biological technology to identify the pathogen. The results showe that the pathogen is A. napiformis Purkayastha et Mallik. The results of pathogen inoculation test show that the symptoms of twice pathogen inoculation test are consistent with the onset of symptoms under natural conditions. Twice inoculations of pathogenic fungi isolate from the same kind. And it proves that fungi pathogenic to C.controversum.4. By taking the method of house culture and mycelium growth rate to study the biological characteristics of the pathogen. The results show that pathogens could grow in the range of 10℃～35℃, the optimum temperature of the mycelium growth is 20℃～25℃ and the best is 25 ℃. Pathogens could grow in the range of 4.0～10.0. The optimum pH value is 6.0～8.0. In a variety of different source of nitrogen and carbon can grow in the growth medium, the yeast powder as the best nitrogen source, lactose as the best carbon source and the optimμm medium for the mycelium growth was vegetable juice medium.5. With drug-containing medium and mycelium growth rate methods inhibiting test is carried out on the pathogen. In 15 kinds of medicine,50% of Yingna wettable powder(WP), 70% of Mancozeb WP and 10% of Difenoconazole water dispeisible granule(WDG) have significant inhibitory effect. Difenoconazole at 4000 times, Mancozeb at 2500 times and Yingna at 1300 times, the average inhibition rate is 100%. |
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