PROBLEM TO BE SOLVED: To provide an excellently safe agent for preventing blast disease, sheath blight or brown spot of rice, having low toxicity; and to provide a method for preventing the blast disease, the sheath blight or the brown spot of the rice. SOLUTION: The agent containing an extract of seaweeds can control the emergence of the blast disease, the sheath blight and the brown spot by being applied at a seedling-raising period and/or a rice paddy period. The time of the application is preferably from seeding to 1.5 leaf stage in the seedling-raising period, and from rice transplanting to 60 days after the rice transplanting in the rice paddy period. The agent for preventing the blast disease, the sheath blight and the brown spot is useful for reduction of agrochemicals for the rice and agrochemical-free cultivation thereof because of hardly having toxicity and being excellently safe. COPYRIGHT: (C)2006,JPO&NCIPI
