Screening of Antagonistic Bacteria SY286 and Its Effect on Grapevine Downy Mildew

Thirty-six samples of grapevine leaves were collected from nine locations in Liaoning province. Three hundred and three bacterial strains were isolated from leaves of grapevine for determining to antagonistic activity in vitro against Plasmopara viticola. Among the tested isolates, 12 isolates showed different levels of antagonism in detached leaf assay, strain SY286 reduced disease severity to the maximum level(93.18%) in detached leaves as well as showed good control effect(above 80%) in the field assay in 2012 and 2013. Inhibition spectrum tests showed that the strain SY286 could significantly inhibit against 10 tested fungal phytopathogens, and the diameter of inhibition zone ranged from 5.93 to 24.90 mm. Based on its characteristics in morphology, physiology, biochemistry and 16S rDNA sequence, we identified strain as Ochrobactrum sp..