Study On Antagonism Of Two Biocontrol Strains To Apple Tree Valsa Canker

Apple tree valsa canker is one of the most destructive diseases all over the worldwith the development of apple trees planting and intensive production. It has causedseriously affects on the development of apple industry. Therefore, the pathogen ofapple tree valsa canker, the incubation period of apple tree valsa canker pathogen andpathogenicity of induced strains were identified and determined. The inhibitoryeffects and induced disease resistance of fulvic acid, screening and Identification ofantagonistic bacteria, inhibitory effects and mechanism to apple tree valsa cankerwere studied in this experiment. The main results were listed as follows.1.Morphological and molecular biological identification were used for theidentification of apple valsa canker in Gansu Province. It was made clear that applevalsa canker caused mainly by Valsa ceratosperma(the anamorph was Cytosporamandshurica), followed by C. carphosperma.2. Incubation period of apple valsa canker decreases with the increase ofmoisture time.While incubation period increased when branch age increased.Incubation period of the alternation of light and darkness every12hours was theshortest at30℃.3. Five isolates of apple tree valsa canker pathogen were enhanced by UVmutagenesis. Pathogenicity of LZU-5isolate showed maximum enhancement extent,the relative growth rate was115.94%. Enhancement extent of LZU-2isolatepathogenicity was the smallest, the relative growth rate was14.50%. Pathogenicity ofLZM-2isolate showed maximum decreasing extent, the relative decreasing rate was46.38%. Decreasing extent of LZM-1isolate pathogenicity was the smallest, therelative decreasing rate was20.29%.4．Fulvic acid had induced resistance to apple tree valsa canker pathogen.Enzyme activities of apple tree valsa canker tissue was significantly differentcompared with the control. SOD, POD, PAL and CAT increased at first and thendecreased. 5．Based on properties of morphology, gram stain and16SrDNA sequenceanalysis. LZ-1201isolate and TS-1203isolate were defined respectively as Bacillussubtilis and Bacillus amyloliquefaciens.6. Two antagonistic bacteria LZ-1201and TS-1203had obvious inhibition tospore germination and mycelial growth of apple tree valsa canker pathogen. Observedby light microscope, Two antagonistic bacteria had teratogenicety to myceliummorphology and cellular structure of apple tree valsa canker pathogen, includingmycelial tapering, twisting, inclusions concentrated, the enlargement deformity of end,color deepened, inclusion overflow of mycelium internode, mycelium break.