Picoxystrobin

 

FRAC 11, C3 Qol; strobilurin type: methoxyacrylate

 

NOMENCLATURE

Common name picoxystrobine ((m) F-ISO); picoxystrobin (BSI, E-ISO) IUPAC name methyl (E)-3-methoxy-2-[2-(6-trifluoromethyl-2-pyridyloxymethyl)phenyl]acrylate
Chemical Abstracts name methyl (E)-(α)-(methoxymethylene)-2-[[[6-(trifluoromethyl)-2-pyridinyl]oxy]methyl]benzeneacetate Strain QST 713 CAS RN [117428–22–5] Development codes ZA 1963 (Zeneca); DPX-YT669 (DuPont). Smiles code CO/C=C(/C(=O)OC)\c1ccccc1COc2cccc(n2)C(F)(F)F;without stereochemistry:COC=C(C(=O)OC)c1ccccc1COc2cccc(n2)C(F)(F)F

 

PHYSICAL CHEMISTRY
Composition Tech. is ≥95% (EU Rev. Rep.). Mol. wt. 367.3 M.f. C₁₈H₁₆F₃NO₄ Form Colourless powder; (tech. is a solid, with creamy colour). M.p. 75 °C V.p. 5.5 × 10^-3 mPa (20 °C) K_ow logP = 3.6 (20 °C) Henry 6.5 × 10^-4 Pa m³ mol^-1 (calc.) S.g./density 1.4 (20 °C) Solubility In water 3.1 mg/l (20 °C). In methanol 96, 1,2-dichloroethane, acetone, xylene and ethyl acetate >250 (all in g/l, 20 °C). Stability Stable at pH 5 and pH 7; DT₅₀ c. 15 d (pH 9, 50 °C) (EU Rev. Rep.).

APPLICATIONS
Biochemistry Quinone outside Inhibitor. Inhibits mitochondrial respiration by blocking electron transfer at the Qo centre of cytochrome bc1. Mode of action Preventive and curative fungicide with unique distribution properties, including systemic (acropetal) and translaminar movement, diffusion in leaf waxes and molecular redistribution in air. Uses For broad-spectrum disease control, including Mycosphaerella graminicola, Phaeosphaeria nodorum, Puccinia recondita (brown rust), Helminthosporium tritici-repentis (tan spot) and Blumeria graminis f.sp. tritici (strobilurin-sensitive powdery mildew) in wheat; Helminthosporium teres (net blotch), Rhynchosporium secalis, Puccinia hordei (brown rust) and Erysiphe graminis f.sp. hordei (strobilurin-sensitive powdery mildew) in barley; Puccinia coronata and Helminthosporium avenae in oats; and Puccinia recondita and Rhynchosporium secalis in rye. Application rate typically 250 g/ha. Formulation types SC.

ENVIRONMENTAL FATE
Animals In rats, well absorbed, extensively metabolised and rapidly eliminated. Metabolism proceeds mainly by ester hydrolysis and glucuronide conjugation. Does not accumulate in meat or milk. Plants Residues in cereals are low (<0.01–0.20 mg/kg). Soil/Environment Rapidly degraded in soils, with CO₂ as the major product; lab. DT₅₀ (aerobic) 19–33 d; field dissipation DT₅₀ 3–35 d. Not mobile in soil under field conditions; K_oc 790–1200 ml/g. Rapid dissipation in water indicates no chronic issues for aquatic organisms; water phase DT₅₀ 7–15 d (lab. and outdoor water sediment systems).

MAMMALIAN TOXICOLOGY
Oral Acute oral LD₅₀ for rats >5000 mg/kg. Skin and eye Acute percutaneous LD₅₀ for rats >2000 mg/kg. Non-irritating to skin and eyes (rabbits). Not a skin sensitiser (guinea pigs). Inhalation LC₅₀ for rats >2.12 mg/l at MMAD >4 μl. NOEL NOAEL (1 y and 90 d) for dogs 4.3 mg/kg b.w. daily. ADI (EC) 0.04 mg/kg b.w. [2003]. Other Non-genotoxic; no developmental toxicity potential (rats and rabbits); no reprotoxicity potential (rats); no carcinogenic potential (rats and mice).

ECOTOXICOLOGY
Birds LD₅₀ for bobwhite quail >2250 mg/kg. Dietary LD₅₀ (8 d) for bobwhite quail >5200 mg/kg. NOEC (21 w) for mallard ducks 1350 mg/kg. Fish LC₅₀ (96 h) (two species) 65–75 μg/l. Daphnia EC₅₀ (48 h) 18 μg/l. Algae E_bC₅₀ (72 h) for Selenastrum capricornutum 56 μg/l. Other aquatic spp. EC₅₀ for Chironomus riparius 19 mg/kg (28 d, dosed to sediment), 140 μg/l (25 d, dosed to water). Bees LD₅₀ (48 h, contact and oral) >200 μg/bee. Worms LC₅₀ (14 d) for Eisenia foetida 6.7 mg/kg soil. Other beneficial spp. Lab. and field tests with 6 species of non-target arthropods indicate low risk to populations. LR₅₀ (7 d) for Typhlodromus pyri 12.6 g/ha; (2 d) for Aphidius rhopalosiphi 280 g/ha.