Bispyribac-sodium
Bispyribac-sodium 95%TC
Bispyribac-sodium 40%SC
Bispyribac-sodium 40%WP
Bispyribac-sodium 10%SC
Herbicide
HRAC B WSSA 2; pyrimidinyloxybenzoic
NOMENCLATURE
Common namebispyribac-sodium (BSI, pa ISO)
IUPAC namesodium 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoate
Chemical Abstracts namesodium 2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy]benzoate
CAS RN[125401-75-4] for acid; [125401-92-5] for sodium saltDevelopment codesKIH-2023; KUH-911 (both Kumiai); V-10029
PHYSICAL CHEMISTRY
CompositionTech. is >93%.Mol. wt.452.4M.f.C19H17N4NaO8; C19H18N4O8for the acidFormWhite powder.M.p.223-224 °CV.p.5.05 ´ 10-6mPa (25 ºC)KOWlogP = -1.03 (23 °C)Henry3.12 ´ 10-11Pa m3mol-1(calc.)S.g./densityBulk density 0.0737 (20 °C, CIPAC MT 3)SolubilityIn water 73.3 g/l (25 ºC). In methanol 26.3, acetone 0.043 g/l (25 °C).StabilityStable in water; DT50>1 y (pH 7 & 9), 448 h (pH 4). Stable to light. Not decomposed after 14 d at 55 °C.pKa3.05
COMMERCIALISATION
HistoryDiscovered in 1988. Reported by Kumiai Chemical Industry Co., Ltd (M. Yokoyama et al., Proc. Br. Crop Prot. Conf. – Weeds, 1993, 1, 61). Developed jointly by Kumiai and Ihara Chemical Industry Co., Ltd and introduced in 1997.PatentsUS 4906285; EP 321846ManufacturersIhara/Kumiai
APPLICATIONS
BiochemistryBranched chain amino acid synthesis (ALS or AHAS) inhibitor.Mode of actionSelective, systemic post-emergence herbicide, absorbed by foliage and roots.UsesControl of grasses, sedges and broad-leaved weeds, especially Echinochloa spp., in direct-seeded rice, at rates of 15-45 g/ha. Also used to stunt growth of weeds in non-crop situations.Formulation typesSC; water-soluble liquid.Selected tradenames:‘Grass-short’ (non-crop land) (Kumiai); ‘Nominee’ (Kumiai); ‘Short-keep’ (non-crop land) (Riken Green)
OTHER TRADENAMES
‘Regiment’ (Valent)
ANALYSIS
By hplc. Details available from Kumiai.
MAMMALIAN TOXICOLOGY
OralAcute oral LD50for male rats 4111, female rats 2635, male and female mice 3524 mg/kg.Skin and eyeAcute percutaneous LD50for rats >2000 mg/kg. Non-irritating to skin; slightly irritating to eyes (rabbits).InhalationLC50(4 h) for rats >4.48 mg/l.NOEL(2 y) for male rats 20 mg/kg diet (1.1 mg/kg b.w. daily), female rats 20 mg/kg diet (1.4 mg/kg b.w. daily), male mice 14.1 mg/kg daily, female mice 1.7 mg/kg b.w. daily.ADI0.011 mg/kg.OtherNon-mutagenic in the Ames test, and non-teratogenic to rats and rabbits.Toxicity classWHO (a.i.) III (Table 5)
ECOTOXICOLOGY
BirdsAcute oral LD50for bobwhite quail >2250 mg/kg. Dietary LC50(5 d) for bobwhite quail and mallard ducks >5620 mg/kg diet.FishAcute LC50(96 h) for rainbow trout and bluegill sunfish >100 ppm.DaphniaLC50(48 h) >100 ppm.AlgaeEC50(120 h) for Selenastrum capricornutum 3.4 mg/l, NOEC 0.625 mg/l.BeesLD50(oral) >200 mg/bee; LC50(contact) >7000 mg/l spray.WormsNOEL (14 d) for Eisenia foetida >1000 mg/kg soil.
