PROBLEM TO BE SOLVED: To provide a technology related to microbial pesticide that is effective against a bacterial disease occurring in a seedling growing season of a gramineous plant and scarcely puts a load on the environment.SOLUTION: This bacterial disease controlling agent includes herbaspirillum-group bacteria, their debris, culture solution of the herbaspirillum-group bacteria, its supernatant solution, and is effective in controlling the bacterial disease of the gramineous plant. This controlling method of the bacterial disease of the gramineous plant has a controlling process of bonding it to the bacterial disease controlling agent. This seed of the gramineous plant is coated with the bacterial disease controlling agent.COPYRIGHT: (C)2012,JPO&INPIT【課題】イネ科植物の育苗期に発生する細菌性病害に有効であり、かつ、環境負荷の少ない微生物農薬に関する技術を提供する。【解決手段】ハーバスピリラム(Herbaspirillum)属細菌又はその破砕物或いはハーバスピリラム(Herbaspirillum)属細菌の培養液又はその上清液を含み、イネ科植物の細菌性病害の防除に有効な細菌病防除剤、細菌病防除剤に付着させる防除処理工程を有するイネ科植物の細菌性病害の防除方法、さらに細菌病防除剤をコートしたイネ科植物の種子により解決する。【選択図】図3