Identification Of Physiological Race Of Erysiphe Cichoracearumdc In Shanxi And Screening Prevetion Research

Tobacco is one of the main economic crops in China, occupies an important position inthe national economy. Tobacco planting area and yield in China occupy the first place in theworld, the current annual planting area of1000,000hm2~1200,000hm2, yield1600,000tonsto2250,000tons. Thus, the pests controlling works in tobacco growth are regarded as a studyemphasis by agronomic researchers. Being one of the main diseases of tobacco, tobaccopowdery mildew has brought great loss to tobacco’s production. Nowadays, there are plentyof controlling methods for this disease, in which the dominating one is chemical pesticidetreatment. However, with more concern on pesticides residue and environment pollution, theuse of chemical pesticides should be reduced, and the principle “Prevention-oriented,integrated control” shall be put into application.Fungus polysaccharide is a kind of natural high molecular compound, widely exists inthe cell wall of fungi especially large fungi, aldehyde and ketone group composed byglycosidic linkages, a three-dimensional structure of spiral, its configuration is similar toDNA, is a kind of polysaccharide of β type. In the international arena, fungal polysaccharidesare known as "biological response modifier ", referred to as "BRM", can control cell divisionand differentiation, regulation of cell growth, anti-virus, mutation resistance, anti-aging,anti-radiation, improve immunity and other biological activity. The Pharmacological functionsof fungi polysaccharides well studied and have drawn much attention. Through the study ofseveral fungicides and fungal polysaccharide screening in order to obtain the agent has strongcontrol effect on tobacco powdery mildew.Studies show that race will continue to the emergence of new tobacco powdery mildew.Therefore, the main type of physiological races of the occurring in China, is the basis forcontrol of tobacco powdery mildew. How to prevent pathogen variation and the emergence ofnew virulent races, this is one of the hot issues of international scientists concerned at present.In this study, from the main tobacco area of Shaanxi province (7counties in southernShaanxi)50tobacco powdery mildew isolates were collected, microscopic observation andidentification of physiological races.50tobacco powdery mildew pathogen isolates were bothErysiphe cichoracearum DC., races are race0and race1, and race1is the dominant races. In addition, through the spore germination method was used to determine the toxicitiesof kresoxim-methyl, three triadimefon, chlorothalonil, tuzet, ethyl-phenol and the controlagent thiophonate-methyl to Erysiphe cichoracearum DC, and field trials were conducted toascertain the effects of50%kresoxim-methyl,15%three triadimefon,50%chlorothalonil,50%tuzet,25%ethyl-phenol and the control agent70%thiophonate-methy on pathogenicity byspray. According to the pathogen virulence determination of analysis results, kresoxim-methyland ethyl-phenol can effectively inhibit Erysiphe cichoracearum DC, provide a more efficientalternative medicine varieties for production.In this study, filter from the of bacteria and library in of the the Qinling original forestthe out of of producing acterium of glucan the strains extract of Coriolus versicolor Quel, tooptimize the mycelium extract of Coriolus versicolor Quel submerged fermentation of theproduction process, determine the the mycelium extract of Coriolus versicolor Quelshake-flask Optimization of fermentation conditions a combination of for thetemperature to26℃, initial pH of6, inoculum10%, liquid volume to100mL speed160r/min. Using theoptimized fermentation conditions versicolor mycelium bottle fermentation, dry myceliumwas2.143g/100ml. And will the preparation of good the Coriolus versicolor glucan is used totobacco powdery mildew prevention and treatment of, through the the of polysaccharidekrestin on the prevention of the tobacco powdery mildew bacteria, the passivation andtreatment trials as, we can see: the Coriolus versicolor glucan on the tobacco the powderymildew germs of have a significant in vitro. The passivation and the prevention the role of, inparticular a very good the is the a tobacco to powdery mildew there are of inhibition ofinfested effect. Spray the Coriolus versicolor glucan200times24h followed by tobaccopowdery mildew pathogen, the inhibition rate up to93.16%.Summarily, this paper through the identification and screening of effective chemicalcontrol of tobacco mildew, provides the theoretical basis for biological control of tobaccopowdery mildew.