The present invention provides a composition for controlling a plant disease comprising a pyridazine compound represented by formula (1) wherein X represents a fluoro atom or a hydrogen atom, and at least one 5-fluorouracil compound selected from the following group (A), and a method for controlling a plant disease, comprising a step of applying each effective amount of the above-mentioned pyridazine compound represented by the formula (1) and the at least one 5-fluorouracil compound selected from the following group (A) to a plant or soil for cultivating the plant, Group (A): a group consisting of 4-amino-5-fluoro-1-tosylpyrimidin-2(1H)-one, 5-fluoro-4-imino-3-methyl-1-tosyl-3,4-dihydropyrimidin-2(1H)-one, and 5-fluoro-3-methyl-4-(methylimino)-1-tosyl-3,4-dihydropyrimidin-2(1H)-one, the composition and method having excellent control efficacies against plant diseases.
