Effectiveness of Bacillus sp. in the prevention of bacterial leaf blight of caused by Xanthomonas oryzae pv. oryzae under field conditions in Cantho city

The study was conducted from June 2018 to September 2018 in Phong Dien district, Can Tho city, to evaluate the effectiveness of Bacillus-R15 strains for preventing bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae under field conditions. The experiment used OM4900 rice variety, including 6 treatments (Bacillus-R15 strain, treated 3, or 7 days intervals, without or combination with 1 spray of chemical bactericide on 5% flowering stage; positive control was Starner 20WP, and negative control), 4 repetitions, arranged in a completely random block design, each experimental plot was 45 m². Record the bacterial leaf blight disease according to IRRI (2013) at the time before treatment of biological control agent and repeated at 7 day intervals until 10 days before harvest, then calculate disease index. The results showed that all treatment with Bacillus-R15 were effective in reducing bacterial leaf blight severity, in which treatment (1) (Bacillus-R15 with 3 day interval sprays or treatment (3) (in combination with one spray of Starner 20WP at 5% heading)  were highly effective in reducing disease severity, with disease suppression were 59.51% and 56.93%, respectively, equal to that of  farmers' practices (Starner 20WP, 1.25‰, two sprays) (59.70%).

Keywords: Bacillus, bacterial leaf blight, Xanthomonas oryzae pv. oryzae.