Abstract: Pyrazole derivatives, preparations thereof, selective herbicidal compositions containing said derivatives and the use of said derivatives are provided. The pyrazole derivatives having selective herbicidal activity are represented by the formula I: ##STR1## wherein, A denotes a straight or branched lower alkylene or lower alkylidene group; X denotes a halogen atom, nitro group, a lower alkyl group, a lower haloalkyl group, a lower alkoxy group, a lower haloalkoxy group, a lower alkenyl group, phenyl group, cyano group, phenoxy group, a lower alkoxycarbonyl group, an aliphatic or aromatic acyl group, methanesulfonyloxy group or group ##STR2## and n is 0 or an integer of 1 to 5, said Xs being the same or different when n is an integer of 2 to 5; and Y denotes a halogen atom, a lower alkyl group, nitro group, phenyl group, a lower alkoxy group or trifluoromethyl group and m is in integer of 1 to 3, said Ys being the same or different when m is 2 or 3.

Abstract: N-(Unsubstituted or substituted pyridyl)aminomethylene-diphosphonic acids represented by the formula: ##STR1## wherein each of R.sup.1, R.sup.2 and R.sup.3 is independently hydrogen or lower alkyl, and each of X and Y is independently hydrogen, halogen, nitro, acetamino, carboxyl, lower alkyl, methoxycarbonyl, hydroxyl or methoxy,and salts thereof, have effective herbicidal effects on postemergence of plants and selective inactivity against cotton plants.