Chemical Identification
Common Name
ethyl 2-chloro-5-(4-chloro-5-difluoromethoxy-1-methylpyrazol-3-yl)-4-fluorophenoxyacetate
ethyl 2-chloro-5-[4-chloro-5-(difluoromethoxy)-1-methyl-1H-pyrazol-3-yl]-4-fluorophenoxyacetate
Molecular Formula
C15H13Cl2F3N2O4; (acid C13H9Cl2F3N2O4)
Molecular Structure
Herbicide.Pyraflufen-ethyl is a light-dependent, contact herbicide which inhibits protoporphyrinogen oxidase, leading to cell destruction. On application to cotton, the injury activates the production of ethylene which accelerates leaf abscission. Pyraflufen-ethyl is rapidly absorbed by the foliage of broadleaf weeds, resulting in necrosis and desiccation. Nihon Nohyaku reports that early post-emergence applications are more effective than late applications. Best results are obtained by applying the product at <6 leaf stage of growth of target weeds. As the product has little residual activity, Nihon Nohyaku does not anticipate any damage to rotational crops.

Pyraflufen-ethyl has shown excellent crop selectivity for wheat and barley.

The product is rainfast within an hour of application. The company recommends thorough coverage of the target vegetation as the product is not systemic. In university testing, cotton defoliation was improved by using a crop oil concentrate. Addition of ammonium sulfate can aid weed control when the target vegetation is under stress.

Tankmixes with products containing glyphosate, dicamba, sulfonylureas or propanil are reported to improve the efficacy of these actives, thus improving burndown, weed spectrum or long-term weed control of targets such as field bindweed, Canada thistle, leafy spurge, purple nutsedge and wild buckwheat. Although pyraflufen-ethyl has a burn-type symptomology, the effects are not so fast as to prevent the translocation of systemic partners. The product can also be used as a harvest aid in cotton and potato. Post-emergence control of weeds in cotton can be achieved through directed sprays where contact with the crops is avoided.

Due to its high activity, the product has a low use rate. In field trials, pyraflufen-ethyl gave similar levels of control to standard treatments with application rates of factors of 250 to 1,000 lower.

In France, the use of pyraflufen in Fizz replaces the use of Foxpro and reduces the active ingredient application by 650 g/ha (of mecoprop-P).
Barley, cotton, maize, potatoes (desiccant), soybeans, sugar cane, sunflowers, wheat, non-bearing deciduous fruit and nuts (not citrus)


0.75 – 2.0 g ai/ha (0.35 – 2.0 oz/acre)

Emulsifiable concentrate. 
Premix Parters: flusilazole; myclobutanil;


AI concn

Emulsifiable concentrate (EC)

2.5% (w/w)

Suspension concentrate (SC)

2% (w/w)

Physical Properties
Molecular weight:413.2; Physical form:Fine, cream-coloured powder. Density:1.565 (24 °C); Composition:Tech. is >96%. Melting point:126-127 °C; Vapour pressure:1.6 × 10-5 mPa(25 °C); Henry constant:8.1 × 10-5 Pa m3 mol-1 (calc.); Partition coefficient(n-octanol and water):logP = 3.49; Solubility:In water 0.082 mg/l (20 °C). In xylene 41.7-43.5, acetone 167-182, methanol 7.39, ethyl acetate 105-111 (all in g/l, 20 °C).; Stability:Stable in water at pH4; DT5013 d ( pH7); rapidly hydrolysed at pH9. Aqueous photolysis DT5030 h.;
(Rat): Oral LD50 >5000 mg/kg; Dermal LD50 >2000 mg/kg. Inhalation LC50 >5.53 mg/l.Non-irritant to skin and slightly irritant to eyes (rabbits). Not a skin sensitiser (guinea pigs).
Environmental Profile
Algae: EC50(96 h) for Selenastrum capricornutum 0.00065, Navicula pelliculosa 0.0054 mg/l.Bees: LD50(oral) >111µg/bee; (contact) >100µg/bee.Birds:Acute oral LD50for bobwhite quail >2000 mg/kg. Dietary LC50for bobwhite quail and mallard ducks >5000 mg/ kg.Daphnia: EC50(48 h) >0.1 ppm.Fish: LC50(48 h) for carp >10, rainbow trout >0.1 ppm.Worms: LC50(14 d) for Eisenia foetida >1000 mg/ kgdry soil. 

Environmental fate: 
Plant:Metabolism proceeds via de-esterification followed by N-demethylation. WATER SOLUBILITY: 82 ppb
Transport Information
Hazard Class:O (Obsolete as pesticide, not classified)

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