Preliminary Study On Wheat Leaf Blight In Tacheng,Xinjiang

Wheat is the main grain crop in Tacheng area of Xinjiang.In 2019,a disease with symptoms suspected of wheat leaf blight was found in the wheat planting area of this area,with a damage area of more than2000 mu.This paper studied the pathogen identification,biological characteristics detection and pesticide screening of leaf blight of Winter Wheat in Tacheng area,in order to find out the causes of the disease and lay a foundation for its occurrence law and control research,the results were as follows:1.Through the isolation and culture of pathogens,pathogenicity determination,morphological observation and molecular biology identification,the species of pathogens of wheat leaf blight caused in Tacheng area,Xinjiang were identified.It was determined that the main pathogens of wheat leaf blight in this area were 4 species of Alternaria and 2 species of Fusarium.166 isolates were obtained by isolation and purification of diseased leaves,and 146 pathogenic strains were obtained by pathogenicity determination,and the isolation frequency was 94%;A total of 106 strains of Alternaria were identified,and the isolation frequency was 68%.Among them,A.alternata accounted for 24%,A.rosae13%,A.infectoria 12%and A.tenuissima 19%;A total of 40 Fusarium strains were isolated,and the isolation frequency was 26%.F.equiseti and F.acuminatum accounted for 13%.2.The biological characteristics of six pathogens were studied,and the main biological characteristics of these pathogens such as nutritional selectivity（utilization of carbon and nitrogen sources）,temperature adaptability（growth temperature,optimal growth temperature and lethal temperature）,acid-base adaptability and light adaptability were clarified.The results showed that:The optimum nitrogen source,growth temperature,p H and light adaptability of the four Alternaria species were the same,which were peptone,28℃,6.5,24 hours sunlight respectively;the best carbon source of A.infectoria was sucrose,and the other three were soluble starch;A tenuissima the lethal temperature is 55℃,and the lethal temperature of the other three species is 53℃.The best carbon source of the two Fusarium species was soluble starch,and the best light condition was 24 hours light.F.equiseti optimum nitrogen source is beef paste,the optimum growth temperature is 28℃,the lethal temperature is 53℃,and the optimum growth p H value is6.5,F.acuminatum optimum nitrogen source is yeast extract powder,the optimum growth temperature is20℃,the lethal temperature is 50℃,and the optimum growth p H value is 7.5.3.The laboratory toxicity test results of 25 Fungicides against 6 pathogens of wheat leaf blight showed that:12.5%fluconazole had the best inhibitory effect on three Alternaria（A.alternata、A.rosae and A.tenuissima）species,the EC₅₀values respectively were 0.295μg/m L,0.099μg/m L and 0.224μg/m L;the inhibitory effect of 43%fluorooxime ester on A.infectoria was the best,and the EC₅₀value was 0.002μg/m L;the inhibitory effect of 30%benzopropiconazole on two kinds of Fusarium（F.equiseti and F.acuminatum）was the best,and the EC₅₀values were 0.682μg/m L and 0.682μg/m L respectively;29%pentazolidinitrate has good inhibitory effect on 4 species of Alternaria and 2 species of Fusarium,and has the potential to prevent multiple pathogens of wheat leaf blight.