Metsulfuron-methyl is a residual sulfonylurea compound used as a selective pre- and postemergence 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. Metsulfuron methyl is used for control of broad leaf weeds like Chenopodium album, Melilotus indica, Medicago hispida, Lathyrus aphaca, Anagallis arvensis, Vicia sativa, Vicia hirsura, Circium arvense in Wheat and Eclipta alba, Luwigia parviflora, Marsilea quadrifoliata in Rice.
MSM is a selective systemic herbicide absorbed through the roots and foliage, which cease the growth almost immediately after post-emergence treatment, and are killed in 7-21 days. It is a branched chain amino acid synthesis inhibitor. Acts by inhibiting of the essential amino acids valine and isoleucine, hence stopping cell division and plant growth. Metsulfuron has activity on many broadleaf weeds and brush. This herbicide is nonselective and is injurious to plants at extremely low concentrations; since most crops are also harmed, major use of metsulfuron is confined to industrial and noncropland areas. Metsulfuron methyl inhibits amino acid production by inhibiting acetolactate synthase. This prevents cell division, resulting in a rapid cessation of growth. This herbicide is quickly absorbed through the leaves, and translocation is systemic. Root uptake also occurs. Preemergence treatments control or suppress weeds through root uptake, while postemergence works through both root and foliar absorbance.