The purpose of the invention is to provide a bactericide composition having even better preventing/controlling effects against agricultural/horticultural bacteria. The invention relates to a synergistic bactericide composition comprising (A) a nitrophenol compound and (B) a bactericidally active compound. The invention relates to a method for preventing/controlling bacteria, characterized by treating a habitat (except for human beings) of agricultural/horticultural bacteria with said synergistic bactericide composition. The invention relates to a plant protection method characterized by treating a plant infested with agricultural/horticultural bacteria, or the vicinity thereof, with said synergistic bactericide composition. The invention relates to a method for using a nitrophenol compound for enhancing bactericidal activity. The invention relates to a bactericidal activity enhancer comprising a nitrophenol compound.本發明之課題在於提供一種對於農園藝病原菌具有更進一步優異之防除效果之殺菌劑組成物。本發明係關於一種協同性殺菌劑組成物，其含有(A)硝基苯酚化合物及(B)殺菌活性化合物。本發明之病原菌防除方法之特徵在於以前述協同性殺菌劑組成物對農園藝病原菌之生存場所(人類除外)進行處理。本發明之植物保護方法之特徵在於以前述協同性殺菌劑組成物對農園藝病原菌所寄生之植物或其附近進行處理。本發明係關於一種硝基苯酚化合物之使用方法，其用以增強殺菌活性。本發明係關於一種殺菌活性增強劑，其含有硝基苯酚化合物。
