TECHNICAL --- HERBICIDE: Metsulfuron-methyl
CAS No.: 74223-64-6
Chemical Abstracts name: methyl
CAS RN: [74223-64-6]
metsulfuron (BSI, WSSA, ANSI, draft E-ISO, (m) draft F-ISO)
Chemical Abstracts name:
CAS RN: [79510-48-8]
Mol. wt.: 381.4
Form: Colourless crystals; (tech., off-white solid, with a faint ester-like odour).
M.p.: 158 篊
V.p.: 3.310-7 mPa (25 篊)
KOW: logP = -1.74 (pH 7)
Henry: 2.310-10 Pa m3 mol-1 (calc.)
Solubility: In water 0.55 (pH 5), 2.79 (pH 7), 213 (pH 9) (all in g/l, 25 篊). In hexane 0.00079, xylene 0.58, ethanol 2.3, methanol 7.3, acetone 36, dichloromethane 121 (all in g/l, 20 篊).
Stability: Stable in air up to c. 140 篊. Hydrolysis DT50 (25 癈), 22 d (pH 5), stable (pH 7 and 9).
Mol. wt.: 367.3 M.f.: C13H13N5O6S Form: Solid.
Biochemistry: Branched chain amino acid synthesis (ALS or AHAS) inhibitor. Acts by inhibiting biosynthesis of the essential amino acids valine and isoleucine, hence stopping cell division and plant growth. Selectivity derives from rapid metabolism in the crop. Metabolic basis of selectivity in sulfonylureas reviewed (M. K. Koeppe & H. M. Brown, Agro-Food-Industry, 6, 9-14 (1995)).
Mode of action: Selective systemic herbicide absorbed through the roots and foliage, with rapid translocation both acropetally and basipetally. Susceptible plants cease growth almost immediately after post-emergence treatment, and are killed in 7-21 days. Surfactants increase the activity of metsulfuron-methyl on certain broad-leaved weeds.
Uses: Metsulfuron-methyl controls a wide range of annual and perennial broad-leaved weeds in wheat, barley, rice and oats, by either pre- or post-emergence application, at 4-7.5 g/ha post-emergence.