The present invention relates to the use of host defense inducers for controlling selected bacterial harmful organisms in useful plants, wherein the bacterial harmful organisms are selected from the group consisting of Acidovorax avenae, Burkholderia spec., Burkholderia glumae, Candidatus Liberibacter spec., Corynebacterium, Erwinia spec., Pseudomonas syringae, Pseudomonas syringae pv. actinidae, Pseudomonas syringae pv. glycinea, Pseudomonas syringae pv. tomato, Pseudomonas syringae pv. lachrymans, Streptomyces spp., Xanthomonas spp., Xanthomonas axonopodis, Xanthomonas axonopodis pv. citri, Xanthomonas axonopodis pv. glycines, Xanthomonas campestris, Xanthomonas campestris pv. musacearum, Xanthomonas campestris pv. pruni, Xanthomonas fragariae and Xanthomonas transluscens. In a preferred aspect of the invention the host defense inducer is isotianil. The present invention also relates to a method for controlling the selected bacterial harmful organisms in useful plants by treatment with a host defense inducer.
