This invention relates to a synergistic herbicidal composition comprising Component A comprised of i) 25 to 40% asulam, or its sodium salt; ii) 10 to 20% of a surfactant; iii) 0 to 1% of an antifoam; iv) 0 to 5% adjuvants and auxiliaries; and v) 40 to 65% water; and Component B comprised of trifloxysulfuron, or its herbicidally effective salts; wherein the ratio of Component A to Component B is in range of 80:1 to 380:1 based on active ingredient. The invention furthermore relates to a method of controlling weeds in crops of useful plants, especially in postemergence sugarcane, and to the use of this novel composition for this purpose.