Products >> Herbicides >> Clopyralid

Clopyralid

Herbicide

HRAC O WSSA 4; pyridinecarboxylic acid

NOMENCLATURE

clopyralid

Common nameclopyralid (BSI, ANSI, draft E-ISO, (m) draft F-ISO); 3,6-dichloropicolinic acid (WSSA, Canada, Finland and, until 1984, BSI; name accepted in lieu of a common name); acide dichloro-3,6 picolinique (France and, until 1984, F-ISO; name accepted in lieu of a common name)

IUPAC name3,6-dichloropyridine-2-carboxylic acid

Chemical Abstracts name3,6-dichloro-2-pyridinecarboxylic acid

Other names3,6-DCPCAS RN[1702-17-6]EEC no.216-935-4Development codesDowco 290 (Dow)

clopyralid-olamine

Common nameclopyralid-olamine

CAS RN[57754-85-5]

PHYSICAL CHEMISTRY

clopyralid

Mol. wt.192.0M.f.C6H3Cl2NO2FormColourless crystals.M.p.151-152 ºCV.p.1.33 mPa (pure, 24 ºC); 1.36 mPa (tech., 25 ºC)KOWlogP = -1.81 (pH 5), -2.63 (pH 7), -2.55 (pH 9), 1.07 (unionised, 25 °C)S.g./density1.57 (20 ºC)SolubilityPure (99.2%) 7.85 (in distilled water), 118 (pH 5), 143 (pH 7), 157 (pH 9) (all in g/l, 20 ºC). In acetonitrile 121, n-hexane 6, methanol 104 (all in g/kg). Forms water-soluble salts, for example potassium, solubility >300 g/l (25 ºC).StabilityDecomposes above m.p. Stable in acidic media and to light; on hydrolysis, DT50>30 d at pH range 5-9 (25 ºC) in sterile water.pKa2F.p.No flashing exhibited in ignition test

 

clopyralid-olamine

Mol. wt.253.1M.f.C8H10Cl2N2O3SolubilityIn water 560 g/l (25 ºC).

COMMERCIALISATION

HistoryHerbicide reported by T. Haagsma (Down Earth, 1975, 30(4), 1). Introduced in France (1977) by Dow Chemical Co. (now Dow AgroSciences).PatentsUS 3317549ManufacturersAgriphar; Dow AgroSciences

APPLICATIONS

BiochemistrySynthetic auxin (acting like indolylacetic acid).Mode of actionSelective systemic herbicide, absorbed by the leaves and roots, with translocation both acropetally and basipetally, and accumulation in meristematic tissue. Exhibits an auxin-type reaction. Acts on cell elongation and respiration.

 

clopyralid

UsesPost-emergence control of many annual and perennial broad-leaved weeds of the families Polygonaceae, Compositae, Leguminosae, and Umbelliferae, in sugar beet, fodder beet, oilseed rape, maize, brassicas, onions, leeks, strawberries, flax and grassland. Provides particularly good control of creeping thistle (Cirsium arvense), perennial sow-thistle, coltsfoot, mayweeds, and Polygonum spp.PhytotoxicityGood crop tolerance of graminaceous, cruciferous crops.Formulation typesSL.Selected tradenames:'Clio' (Agriphar); 'Cyronal' (Aventis); 'Diclopyr' (Agrimix); mixtures:'Scorpion' (+ benazolin+ dimefuron) (Aventis)

clopyralid-olamine

Selected tradenames:'Lontrel 35A' (Dow AgroSciences); 'MatriKerb' (PBI)

 

OTHER TRADENAMES

clopyralid

'Dow Shield' (Dow AgroSciences) mixtures:'Broadstrike Plus' (+ flumetsulam) (Dow AgroSciences); 'Broadstrike Post' (+ 2,4-D+ flumetsulam) (Dow AgroSciences); 'Chardex' (+ MCPA) (Dow AgroSciences); 'Confront' (+ triclopyr) (Dow AgroSciences); 'Curtail M' (+ MCPA-2-ethylhexyl) (Dow AgroSciences); 'Grazon 90' (+ triclopyr) (Dow AgroSciences); 'Hornet' (+ flumetsulam) (Dow AgroSciences); 'Lonpar' (+ 2,4-D+ MCPA) (Dow AgroSciences); 'Pastor' (+ fluroxypyr+ triclopyr) (Dow AgroSciences); 'Redeem' (+ triclopyr-triethylammonium) (clopyralid as triethylammonium salt) (Dow AgroSciences); 'Scorpion III' (+ 2,4-D+ flumetsulam) (Dow AgroSciences); 'Vindex' (+ bromoxynil) (Dow AgroSciences); 'Accent Gold' (+ flumetsulam+ nicosulfuron+ rimsulfuron) (Du Pont); 'Benazalox' (+ benazolin) (Aventis); 'Matrikerb' (+ propyzamide) (Rohm & Haas); 'Scorpio' (+ benazolin+ dimefuron) (Aventis) Discontinued names mixtures:'Crusader S' * (+ bromoxynil+ fluroxypyr+ ioxynil) (Dow); 'Hotspur' * (+ fluroxypyr+ ioxynil) (Dow)

clopyralid-olamine

'Reclaim' (Dow AgroSciences); 'Stinger' (Dow AgroSciences); 'Transline' (Dow AgroSciences) mixtures:'Curtail' (+ 2,4-D) (2,4-D is triisopropanolammonium salt) (Dow AgroSciences)

ANALYSIS

Product analysis by glc. Residues determined by glc of a derivative (A. J. Pik & G. W. Hodgson, J. Assoc. Off. Anal. Chem., 1976, 59, 264). Details available from Dow AgroSciences.

MAMMALIAN TOXICOLOGY

clopyralid

OralAcute oral LD50for male rats 3738, female rats 2675 mg/kg.Skin and eyeAcute percutaneous LD50for rabbits >2000 mg/kg; a severe eye irritant, not a skin irritant.InhalationLC50(4 h) for rats >0.38 mg/l.NOEL(2 y) for rats 15, male mice 500, female mice >2000 mg/kg b.w. daily.ADI0.15 mg/kg.OtherNon-carcinogenic, non-mutagenic, non-teratogenic, and produces no significant toxicological effects on reproductive parameters.Toxicity classWHO (a.i.) III (Table 5); EPA (formulation) IVEC hazardXi; R41| N; R51, R53

ECOTOXICOLOGY

clopyralid

BirdsAcute oral LD50for mallard ducks 1465, bobwhite quail >2000 mg/kg. Dietary LC50(5 d) for mallard ducks and bobwhite quail >4640 mg/kg diet.FishLC50(96 h) for rainbow trout 103.5, bluegill sunfish 125.4 mg/l.DaphniaEC50(48 h) 225 mg/l. EC50(21 d) immobilisation 69, reproduction 80 mg/l; NOEC 17 mg/l.AlgaeEC50(96 h) for Selenastrum capricornutum, cell count 6.9, cell volume 7.3 mg/l.Other aquatic spp.EC50(14 d) for Lemna gibba 89 mg/l.BeesNon-toxic to bees. LD50(48 h, oral and contact) >100 mg/bee.WormsLC50(14 d) for earthworms >1000 mg/kg soil.Other beneficial spp.No effect on nitrification, nitrogen fixation or degradation of cellulose, starch, protein and leaf material at 1-10 ppm.