Special Metsil Combo is selective herbicide containing Metsulfuron methyl 20% WP as active ingredient. Special Metsil Combo is a residual sulfonylurea compound used as a selective pre and post emergence herbicide for broadleaf weeds and some annual grasses. It is a systemic compound with foliar and soil activity, and it works rapidly after it is taken up by the plant. Its mode of action is by inhibiting cell division in the shoots and roots of the plant, and it is biologically active at low use rates.