Pyraclostrobin

FRAC 11, C3  Qol; strobilurin type: methoxycarbamate

 

NOMENCLATURE
Common name pyraclostrobine ((f) F-ISO); pyraclostrobin (BSI, E-ISO)  IUPAC name methyl N-{2-[1-(4-chlorophenyl)pyrazol-3-yloxymethyl]phenyl}(N-methoxy)carbamate
Chemical Abstracts name methyl [2-[[[1-(4-chlorophenyl)-1H-pyrazol-3-yl]oxy]methyl]phenyl]methoxycarbamate  Other names F500 (registered trademark). CAS RN [175013–18–0] Smiles code CON(C(=O)OC)c1ccccc1COc2ccn(n2)c3ccc(Cl)cc3

PHYSICAL CHEMISTRY
Composition Tech. is ≥97.5% pure. Mol. wt. 387.8 M.f. C₁₉H₁₈ClN₃O₄  Form White or light beige, solidified melt.  M.p. 63.7–65.2 °C  B.p. Decomp. 200 °C V.p. 2.6 × 10^-5 mPa (20 °C) K_ow logP = 3.99 (20 °C) Henry 5.3 × 10^-6 Pa m³ mol^-1 (calc.) S.g./density 1.367 (20 °C) Solubility In water 1.9 mg/l (20 °C). In n-heptane 3.7, isopropanol 30.0, octanol 24.2, olive oil 28.0, methanol 100.8, acetone, ethyl acetate, acetonitrile, dichloromethane and toluene >500 (all in g/l, 20 °C). Stability Stable >30 d (pH 5–7, 25 °C). Photolysis DT₅₀ in water 1.7 d.

APPLICATIONS
Biochemistry Quinone outside Inhibitor. Inhibits mitochondrial respiration by blocking electron transfer at the cytochrome bc1 complex.

Mode of action Fungicide with protectant, curative and translaminar properties. Also causes physiological effects like delayed senescence, greener leaves, better tolerance against biotic and abiotic stress, as well as more efficient use of water and nitrogen.

Uses Control of major plant pathogens, such as Septoria tritici, Puccinia spp., Drechslera tritici-repentis, Pyrenophora teres, Rhynchosporium secalis and Septoria nodorum in cereals, Mycosphaerella spp. in peanuts, Septoria glycines, Cercospora kikuchii and Phakopsora pachyrhizi in soya beans, Plasmopara viticola and Erysiphe necator in grapes, Phytophthora infestans and Alternaria solani in potatoes and tomatoes, Sphaerotheca fuliginea and Pseudoperonospora cubensis in cucumber, Mycosphaerella fijiensis in bananas, Elsinoë fawcettii and Guignardia citricarpa in citrus, and Rhizoctonia solani and Pythium aphanidermatum in turf. Application rates c. 50–250 g/ha for food crops and 280–560 g/ha for turf. Depending on region and location, the efficacy of strobulurins may be reduced by resistance.

Formulation types EC; SE; WG; SC; FS.

ANALYSIS
Determination of residues in soil by lc/ms (Environ. Chem. Methods).

ENVIRONMENTAL FATE
Animals In rats, rapidly absorbed and completely eliminated within 5 d, mainly via faeces. Extensively metabolised (>95%) with nearly 50 metabolites, formed by N-demethoxylation, hydroxylation, cleavage of the ester bond and further oxidation of the resulting metabolites, followed by conjugation with glucuronic acid or sulfate. Soil/Environment DT₅₀ (lab, aerobic, 20 °C) 12–101 d (5 soils); (field) 8–37 d (6 locations). K_oc 6000–16 000 ml/g.

TOXICOLOGICAL & ENVIRONMENTAL REVIEWS
JMPR Mtg. 101 (2004), 107 (2006); JMPR Evaln. I 102 (2004), 108 (2006); JMPR Evaln. II 100 (2003). EU Rev. Rep. SANCO/1420/2001, Sep. 2004. EU Status (1107/2009) Approved, 2004/30/EC; extended to include plant growth regulator use 2009/25/EC; proposed extension to 31 Jan 2017.

MAMMALIAN TOXICOLOGY
Oral Acute oral LD₅₀ for rats >5000 mg/kg. Skin and eye Acute percutaneous LD₅₀ for rats >2000 mg/kg. Irritating to skin; non-irritating to eyes (rabbits). Inhalation LC₅₀ (4 h) for rats 0.58 mg/l. NOEL (2 y) for rats 75 ppm (3 mg/kg b.w. daily); (28 d, prenatal development) for rabbits 3 mg/kg b.w. daily; (90 d) for mice 30 ppm (4 mg/kg b.w.. daily). ADI (JMPR, EC) 0.03 mg/kg b.w. [2003, 2004, 2006]; (FSC) 0.034 mg/kg b.w. [2005]. Other No mutagenic potential (5 tests); no teratogenic potential (rats, rabbits); no carcinogenic potential (rats, mice); no adverse effects on reproduction (rats). EPA (formulation) Not likely to be carcinogenic to humans. EC classification T; R23| Xi; R38| N; R50, R53| concn. dep.

ECOTOXICOLOGY
Birds Acute oral LD₅₀ for bobwhite quail >2000 mg/kg b.w. Dietary LC₅₀ (5 d) for bobwhite quail >1176 mg a.s./kg b.w../d. Fish LC₅₀ (96 h) for rainbow trout 0.006 mg/l. Daphnia EC₅₀ (48 h) 0.016 mg/l. Algae E_rC₅₀ (72 h) for Pseudokirchneriella subcapitata >0.843 mg/l; E_bC₅₀ (72 h) for Pseudokirchneriella subcapitata 0.152 mg/l. Other aquatic spp. Mesocosm NOEC 0.008 mg/l. Bees LD₅₀ (oral) >73.1 μg/bee; (contact) >100 μg/bee. Worms LC₅₀ 567 mg/kg soil. Other beneficial spp. Based on sequential testing procedures for non-target arthropods and the relevant classification schemes, pyraclostrobin can be considered to be of low risk to populations of Typhlodromus pyri, Aphidius rhopalosiphi, Aleochara bileneata and Chrysoperla carnea, representing the most sensitive species and the two general indicator species.