摘要:
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.