Identification of Tomato Bacterial Spot Disease, Caused by X.euvesicatoria and Its Screening of Biocontrol Bacteria

Seven strains were isolated from diseased leaves from tomato. The same strains were re-isolated from inoculated leaves by the Koch's rule. The pathogen was identified as Xanthomonas campestris pv.vesicatoria (Dye) according to the characters of cultural colonies, morphological observation, biochemical and physiological identification (Biolog carbon source utilization analysis), 16S rDNA sequences analysis and further pathogenicity determination. Seven biocontrol bacteria were selected for the greenhouse experiment, based on the results of plate antibacterial test.The biocontrol bacteria control efficiency on tomato bacterial spot was determined by spray and seed soaking inoculation of biocontrol bacteria. Three strains were screened out which had a significant control effect on tomato bacterial spot disease. The disease control efficiency of C3, R2-2, HY (Bacillus amyloliquefaciens, Bacillus methylotrophicus, Lysobacter antibioticusstrain) strains were always higher than 65%. The results showed that strain C3 had a significant control effect of 83.36%, when seed soaking inoculation of biocontrol bacteria, while the strain HY had a significant control effect of 76.18%, when spray inoculation of biocontrol bacteria. Strains 1-7 and M3 were affected the maximum and minimum by two different inoculation methods, respectively.