Acibenzolar-S-methyl efficacy against bacterial brown stripe caused by Acidovorax avenae subsp. avenae in creeping bentgrass

Bacterial brown stripe caused by Acidovorax avenae subsp. avenae (Aaa) causes serious damage on creeping bentgrass on golf course greens. However, there are few effective control strategies. Acibenzolar-S-methyl (ASM), a synthetic analog of salicylic acid (SA), has been used to protect plants from diseases by activating plant defense. Here, we demonstrated that bacterial populations were reduced at least 10 times after ASM pretreatment when plants were clip-inoculated with Aaa. In tests of ASM against Aaa on creeping bentgrass in golf courses, the preventive efficacy of ASM was 43–71% and curative efficacy was 57–86%. We also demonstrated that dip-inoculations of creeping bentgrass with Aaa caused disease and that pretreatment with ASM reduced bacterial populations. In a study of stomatal response after Aaa inoculation and ASM treatment, within 1 h, ASM systemically induced stomatal closure, which lasted for at least 1 week. These results suggest that ASM confers immediate, continuous stomatal closure in creeping bentgrass and provides powerful bacterial control in creeping bentgrass.