Screening, Identification and Application of Antagonistic Bacteria Against Tobacco Wildfire Disease

In order to screen out antagonistic bacteria against tobacco wildfire disease, develop a new biological pesticide for preventing and controlling tobacco wildfire disease and reduce the pesticide residue in tobacco,14 strains of antagonistic bacteria against tobacco wildfire bacteria disease were screened out from 287 isolates separated from healthy tobacco leaves by way of streak on plate method. The strains were identified as Bacillus subtilis basing on 16S rDNA sequence. The inhibition zone of the most antagonistic strains was 9.3 mm in width. After spraying inoculation antagonistic bacteria to tobacco plants, the activities of phenylalanine ammonialyase (PAL),peroxide enzyme (POD) and polyphenoloxidase (PPO) in tobacco leaves increased significantly. The test results showed that the control efficiency was 97.54% for the treatment of spraying antagonistic bacteria before inoculating pathogen bacteria in contrast with 41.44% for the control (spraying agro-streptomycin). The control efficacy was 51.40% for the treatment of spraying antagonistic bacteria to tobacco plants after inoculating pathogen bacteria in contrast with 50.69% for the control (spraying agro-streptomycin). It indicated that the preventive effect of antagonistic bacteria was significantly higher than that of agro-streptomycin,and its preventive effect was better than its treatment effect.