A plant disease controlling composition containing a pyridazine compound represented by formula (I):wherein R1 represents a chlorine atom, a bromine atom, a cyano group, or a methyl group, and R2 represents a hydrogen atom or a fluorine atom andat least one QoI compound selected from the group consisting of dimoxystrobin, azoxystrobin, fluoxastrobin, pyraclostrobin, famoxadone, kresoxim-methyl, picoxystrobin, trifloxystrobin, N-methyl-α-methoxyimino-2-[(2,5-dimethylphenoxy)methyl]phenylacetamide, and fenamidone.
