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Bispyribac-Sodium

Herbicide
HRAC B WSSA 2; pyrimidinyloxybenzoic

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Bispyribac-Sodium NOMENCLATURE
Common name bispyribac-sodium (BSI, pa ISO)
IUPAC name sodium 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoate
Chemical Abstracts name sodium 2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy]benzoate
CAS RN [125401-75-4] for acid; [125401-92-5] for sodium salt Development codes KIH-2023; KUH-911 (both Kumiai); V-10029

Bispyribac-Sodium APPLICATIONS
Biochemistry Branched chain amino acid synthesis (ALS or AHAS) inhibitor. Mode of action Selective, systemic post-emergence herbicide, absorbed by foliage and roots. Uses Control 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 types SC; water-soluble liquid. Selected tradenames: 'Grass-short' (non-crop land) (Kumiai); 'Nominee' (Kumiai); 'Short-keep' (non-crop land) (Riken Green)

Bispyribac-Sodium OTHER TRADENAMES
'Regiment' (Valent)

Bispyribac-Sodium ANALYSIS
By hplc. Details available from Kumiai.

Bispyribac-Sodium MAMMALIAN TOXICOLOGY
Oral Acute oral LD50 for male rats 4111, female rats 2635, male and female mice 3524 mg/kg. Skin and eye Acute percutaneous LD50 for rats >2000 mg/kg. Non-irritating to skin; slightly irritating to eyes (rabbits). Inhalation LC50 (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. ADI 0.011 mg/kg. Other Non-mutagenic in the Ames test, and non-teratogenic to rats and rabbits. Toxicity class WHO (a.i.) III (Table 5)

ECOTOXICOLOGY
Birds Acute oral LD50 for bobwhite quail >2250 mg/kg. Dietary LC50 (5 d) for bobwhite quail and mallard ducks >5620 mg/kg diet. Fish Acute LC50 (96 h) for rainbow trout and bluegill sunfish >100 ppm. Daphnia LC50 (48 h) >100 ppm. Algae EC50 (120 h) for Selenastrum capricornutum 3.4 mg/l, NOEC 0.625 mg/l. Bees LD50 (oral) >200 mg/bee; LC50 (contact) >7000 mg/l spray. Worms NOEL (14 d) for Eisenia foetida >1000 mg/kg soil.

ENVIRONMENTAL FATE
Animals >95% of dose applied to rats was excreted in urine and faeces within 7 d. Plants Following application to foliage and soil at 5-leaf stage of rice plants, c. 10% of carbon label was distributed between straw and roots at harvest. Soil/Environment In soil, DT50 <10 d (flooded and upland conditions).