A
pesticide having stabilized high pesticidal effects for
crop plants infected with
plant diseases, is presented. The
pesticide contains a
biphenyl derivative represented by the formula (I) or its salt, as an
active ingredient: wherein X, Y and Z are each independently a
halogen atom, a hydroxyl group, a
formyl group, an
alkyl group which may be substituted, an
alkoxy group which may be substituted, an alkylthio group, an alkylsulfonyl group, an alkylsulfinyl group, or the like, A is a
carbonyl group, a thiocarbonyl group, an alkylene group, or a
single bond, R1 and R2 are each independently a
hydrogen atom, an
alkyl group which may be substituted, an alkenyl group which may be substituted, an alkynyl group which may be substituted, an
aryl group which may be substituted, a
formyl group, an alkylcarbonyl group, a cyano group, or the like, and m and n are each independently 0, 1, 2, 3 or 4.