A microorganism selected from the group consisting of a Bacillus sp. ITB090 strain (NITE BP-01725), a Bacillus sp. ITB100 strain (NITE BP-01726), and a Bacillus sp. ITB105 strain (NITE BP-01727), or a variant strain derived therefrom is used to control plant diseases, control nematodes, promote plant growth, and the like.