Isolation And Identification Of Cherry Crown Gall Disease Pathogen And Its Chemical Control

Cherry crown gall disease was serious in cherry orchard of Baqiao District, Xi’an, Thecrown gall occurred on cherry tree stem and branch above the ground that seriously damagedthe tree phloem tissue and hindered the tree nutrient transport, which gradually resulted in aweakened tree or the death of tree. Cherry crown gall disease caused great economic losses.It is urgent to identify cherry crown gall disease pathogen and sclect eutherapeuticchemical.The isolation and identification of pathogen of cherry crown gall disease in BaqiaoXi’an were studied, while the disease occurred above the ground the pathogenesis wasdiscussed, which has laid the foundation of effective prevention and control of the disease.Pathogenicity test was based on Koch’s postulate. Microscopical examination, pathogenisolation, pathogenicity test, physiological and biochemical test combined with MolecularBiology methods were used to indentify pathogen. Chemical control test was done on theorchard, Taiwan number5, Beibo and the other14kinds of chemical agents were used forthe test. These following conclusions were made based on the research.1.6Strains of bacteria and1strain of fungus were isolated from the crown gall. In thepathogenicity test, carrot disk, tobacco stem and one year old cherry branch were inoculatedwith all isolates, the position inoculated with CG04could grow tumor and the same straincould be isolated from the new tumor.16S rDNA sequence of strain CG04has beensubmitted to NCBI in order to do the BLAST (Registry Number: KC107786), those strainswhose homology higher than98%were all Agrobacterium spp.2. CG04was identified to be Agrobacterium tumefaciens (biological type I strain)upon biochemical test and molecular result. The pathogen of cherry crown gall disease wasidentified to be biological type I strain of Agrobacterium tumefaciens.3. PCR amplification reaction used tms2primers showed a220bp DNA sequence whichmeant agrobacterium T-DNA region had been intergrated into the tumor of cherry branch. Itproved that cherry crown gall disease pathogen was Agrobacterium tumefaciens. 4. CZ01、CZ02and CZ03were isolated from the crown gall which could leadGummosis on the tumor. CZ01and CZ02were identified to be Pseudomonas while CZ03tobe Fusarium lateritium according to their16S rDNA sequence.5. Concerning with the chemical control test. Using the methods of scraping tumor andapplying pesticides, the cure rate of Tai wan number5, Beibo and Bordeaux mixture were87%、85%and78%respectively which were higher than lime sulphur and Tai wan number1(P<0.01). On the spraying method, the tumor fatality rate of200times potassiumpermanganate﹢400times quintozene and1000times streptomycin﹢500times allicin were56%and58%respectively which were significantly higher than other treatments (P <0.01).