PURPOSE: A disinfectant for seed showing strongly controlling effect on bakanae disease of rice plant by synergistic action, comprising a mixture of bis(2- pyridyl-1-oxide)disulfide and a specific fungicide for agriculture and horticulture as an active ingredient.

CONSTITUTION: 1pt.wt. compound shown by the formula I is blended with 0.2W5.0pts.wt. methyl-1-(butylcarbamoyl)-2-benzimidazole carbamate shown by the formula II, 1,2-di(3-methoxycarbonyl-2-thioureido)benzene shown by the formula III, N[(trichloromethyl)thio]-4-cyclohexene-1,2-dicarboximide shown by the formula IV, bis(dimethylthiocarbamoyl)disulfide shown by the forumula V, tetrachloroisophthalonitrile shown by the formula VI and/or dizinc bis(dimethyldithiocarbamate)ethylenebis(dithiaocarbamate) shown by the formula VII. A wide range of blights can also controlled with the disinfectant.