PROBLEM TO BE SOLVED: To provide a composition that has an excellent control effect for plant diseases.SOLUTION: This composition for controlling plant diseases contains a pyridazine compound represented by formula (I), and a compound represented by the following formula (A).【課題】植物病害に対する優れた防除効果を示す組成物を提供すること。【解決手段】式(I)で示されるピリダジン化合物と、式(A)で示される化合物とを含有する植物病害防除組成物。式(A):【選択図】なし