The present invention generally relates to an aqueous herbicidal formulation that comprises at least one phenoxy acid herbicide or an agriculturally acceptable salt or derivative thereof, and an alkylamidopropyl dialkylamine surfactant adjuvant, wherein said surfactant adjuvant comprises at least one surfactant having the formula (I) wherein R is a straight or branched chain, saturated or unsaturated acyl group having 6-22 carbon atoms, n is 3, and Y and Y&prime； are, independently, an alkyl group having 1-4 carbon atoms or (AO)sH, wherein AO is an alkyleneoxy group having 2-4 carbon atoms, and s is on average 1-10； provided that at least one of the groups Y and Y&prime； is an alkyl group having 1-4 carbon atoms； or a salt thereof； or a quaternized derivative of (I) having the formula (II) wherein R is a straight or branched chain, saturated or unsaturated acyl group having from 6 to 22 carbon atoms； n is 3； Y and Y&prime； are, independently, an alkyl group having 1-4 carbon atoms or (AO)sH, wherein AO is an alkyleneoxy group having 2-4 carbon atoms, and s is on average 1-10； provided that at least one of the groups Y and Y&prime； is an alkyl group having 1-4 carbon atoms； R2 is a C1-C4 alkyl group； and X&minus； is an anion. The invention also relates to a method for combating unwanted vegetation which comprises applying to said unwanted vegetation an effective amount of the aforementioned herbicidal formulation.
