PROBLEM TO BE SOLVED: To provide a technique relating to a microorganism control agent with less environmental load, which is effective for controlling a bacterial disease such as a rice seedling wilt bacteria disease, a rice-in-husk wilt bacteria disease (a seedling putrefactive disease), and a rice-in-husk wilt bacteria disease (a rice-in-husk wilt disease) arising in a raising-seedling period, and an ears-forming period of a gramineous plant.SOLUTION: A bacterial disease control agent includes at least one species selected from the group consisting of a culture liquid, a culture supernatant, and bacterial cells of nonpathogenic Pantoea ananatis bacteria for controlling a bacterial disease of a gramineous plant of at least one species selected from the group consisting of a rice seedling wilt bacteria disease, a rice-in-husk wilt bacteria disease (a seedling putrefactive disease), and a rice-in-husk wilt bacteria disease (a rice-in-husk wilt disease). A control method of a bacterial disease of a gramineous plant includes a control treatment step of attaching the bacterial disease control agent to seeds or ears. Also provided are seeds of a gramineous plant coated with the bacterial disease control agent.
