IDENTIFICATION
Common name: Glufosinate-ammonium
Chemical abstracts name: ammonium (±)-2-amino-4-(hydroxymethylphosphinyl)butanoate
Type: Herbicide
CAS RN: unstated stereochemistry
M.F.: C5H15N2O4P
Mol Wt: 198.2
PHYSICAL CHEMISTRY
Form (appearance): Crystalline solid, with a slightly pungent odour.
M.P.: 215℃
V.P.: <0.1 mPa (20℃)
S.G.: 1.4 (20℃)
Solubility.: In water 1370 g/t (22℃). In acetone 0.16, ethanol 0.65, ethyl acetate 0.14, toluene 0.14, hexane 0.2 (all in g/I, 20℃).
Stability: Stable to light.
Henry: 4.48 × 10-9 Pa m3 mol-1 (talc.)
KowlogP: <0.1 (pH 7, 22℃)
APPLICATION
Formulation types: SL.
Biochemistry: Glutamine synthetase inhibitor; leads to accumulation of ammonium ions, and inhibition of photosynthesis.
Mode of action: Non-selective contact herbicide with some systemic action. TranstocatJon occurs only within leaves, predominantly from the leaf base to the leaf tip.
Uses: Glufosinate ammonium is used for control of a wide range of annual and perennial broad-leaved weeds and grasses in fruit orchards, vineyards, rubber and oil palm plantations, ornamental trees and bushes, non-crop land, and pre-emergence in vegetables. Also used as a desiccant in potatoes, sunflowers, etc. For control of annual and perennial weeds and grasses in glufosinate-tolerant crops (oilseed rape, maize, soya beans, sugar beet) developed through gene technology.
Compatibility: Compatible with diuron, simazine, MCPA, and some other herbicides.
MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for male rats 2000, female rats 1620, male mice 431, female mice 416, dogs 200-400 mg/kg.
Skin and eye: Acute percutaneous LD50 for male rats >4000, female rats c. 4000 rog/kg. Not a skin or eye irritant.
Inhalation: LC50 (4 h) for male rats 1.26, female rats 2.60 mg/t air (dust); for rats>0.62 mg/l air (aerosol).
Noel: (2 y) for rats 2 mg/kg b.w. daily.
ADI: (JMPR) 0.02 mg/kg b.w. [1991].
Other No teratogenic, carcinogenic, mutagenic or neurotoxic effects have been observed.
Toxicity: WHO (a.i.) III; EPA (formulation) III
EC hazard: Xn: R22
ECOTOXICOLOGY
Birds: Dietary LC50 (8 d) for Japanese quail >5000 mg/kg.
Fish: LC50 (96 h) for rainbow trout 710, carp, bluegill sunfish, golden orfe >1000 mg/l.
Daphnia: LC50 (48 h) 560-1000 mg/l.
Algae: LD50 for Scenedesmus subspicatus ≥1000, Selenastrum capricornutum 37 mg/l.
Worms: LD50 for earthworms >1000 mg/kg soil.
/Bees: Not hazardous to bees; LD50 >100 μg/bee.
Other beneficial spp. Not toxic to beneficial arthropods.
ENVIRONMENTAL FATE
Plant: Non-selective use: only the metabotite, 3-methylphosphinico-propionic acid (3 MPP), is taken up in traces from the soil. Desiccation: most of the residues consist of parent glufosinate-ammonium with minor amounts of metabolite 3-MPP. Selective use: the principal metabolite is N acetytglufosinate, with lesser amounts of parent and 3 MPP.
Animals: Rapidly excreted, predominantly via faeces (90%). The principal metabolite is 3-methylphosphinico-propionic acid (3 MPP). A further faecal metabolite is N-acetylglufosinate, formed by intestinal micro-organisms.
Soil/Environment: Rapidly degraded in surface levels of soil, and in water. Because of polarity, it and its metabolites do not bioaccumulate. Metabolism in soil and water reviewed (E. Dorn et al., Z. Pfianzenkr. Pfianzenschutz, 1992, Sonderheft XIII, pp. 459 468). Degraded to 3-methylphosphinico-propionic acid (3-MPP) and 2 -methylphosphinico-acetic acid, and ultimately to CO2 and bound residues. In soil, DT50 3-10 d (lab.), 7-20 d (field); DT50 10-30 d (lab.); DT50 of metabolites 7-19 d (lab.). DT50 in water c. 2-30 d. Lysimeter studies and model calculations show that neither a.i. nor metabolites leach into groundwater; this appears to be due to rapid degradation, and adsorption to certain soil elements. Adsorption is more correlated with clay content than organic matter, Kclay 2-115, Koc 10-1230 (A. Zumdick et al., Proc. 9th IUPAC Int. Congr. Pestic. Chem., London, 1998, 2, 6A-023; idem, ibid., 6D-034). |
