Screening Of Fungicides And Antagenistic Microbes Angaist Apple Valsa Canker Pathogen In Vitro And In Vivo

Shaanxi is the main apple-producing base in China. Apple industry had become one of the six important industries of Shaanxi. But recently, the apple tree valsa canker cause by Cytospora spp occurred seriously and prevalently, which had became a threaten that held back the apple industry development. The situation of yield losing caused by the pathogens and the prospect of the orchard destroyed by the pathogens had often been seen in the field. Once the trees were infected by the microbes, the trees restored health very difficulty. Recently, chemical control is the mainly means to control apple valsa canker in china, but This way to control apple valsa canker cause some matter. For example, environment pollution,pesticide residue,food safety and so on. As chemical control, biocontrol also have some defects: poor colonization ability, poor stability, environmental impact ect. Consequently, this research has studied the Mixtures of fungicides and endophyte to control apple valsa canker. The results were obtained listed as follows:1. This research have studied the effects of 349 endophytes on conidia germination, the result showed that 12 endophytes have good inhibitory effect .the 12 endophytes are GCLA 4,GPLA2,GPLA9,TIASA16,CR23,AR1-14,TGYXCSA1,TGYXCSA7,BAR1-5,TGNBA12,TGNBA13å’ŒBDX. All of the antifungal band of this 12 endophytes >5mm, According to this result, this research have studied the effect of 12 endophytes to inhibit conidia Germination. The result showed that the highest inhibitions were got from treatment of BAR1-5 in conidia Germination. GPLA2 had less effect on the conidia Germination of Valsa ceratosperma. The result of excised twigs assay indicated that the highest inhibitions were got from treatment of BAR1-5.2. The effects of 15 fungicides on conidia germination, mycelium growth and excised twigs assay of Valsa ceratosperma. The results showed that conidia germination and colony diameters were strongly inhibited by 15 fungicides in test concentration except Metalaxyl, Polyoxin and Carbendazim. The highest inhibitions were got from treatment of Difenoconazole in conidia germination. It's EC50 values were very low. Thiophanate-methyl had less effect on the pathogens. The result of excised twigs assay indicated that the highest inhibitions were got from treatment of Humic acids&asomate.3. Base on the result of part 1and part 2, this research has studied the effect of mixture to inhibit this pathogen. The result shows that the best mixing proportion of Difenoconazole and BAR1-5 is1: 3; The best mixing proportion of Polyoxin and BAR1-5 is1: 3.The best mixing proportion of Difenoconazole and gCLA4 is1: 1; The best mixing proportion of Polyoxin and gCLA4 is1: 3. The result of the field experiment shows that the highest inhibitions were got from treatment of Difenoconazole and BAR1-5's mixture.