The present invention addresses the problem of providing an agricultural and horticultural germicide composition that exhibits an excellent control effect against plant diseases even in a small amount, and that is not a cause for concern regarding phytotoxicity with respect to useful plants. This agricultural and horticultural germicide composition includes: at least one compound A selected from the group consisting of compounds and the like represented by formula (1) {In formula (1): each X is independently a halogeno group or a C1-C6 alkyl group； n represents the number of the Xs and is an integer from 0 to 5； X' is a halogeno group； R1, R2, and R3 are each independently a C1-C6 alkyl group, a C1-C6 alkoxy group or a hydroxyl group； and A1 and A2 are each independently a nitrogen atom or a carbon atom.}； and one compound B selected from the group consisting of silthiofam, an antibiotic, propineb, and chinomethionat.
