Common name: difenoconazole

IUPAC name: cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl ether

Chemical Abstracts name: 1-[2-[4-(4-chlorophenoxy)-2-chlorophenyl]-4-methyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole

CAS RN: [119446-68-3] unstated stereochemistry

 

Composition: Ratio of cis- to trans- isomers is in the range 0.7 to 1.5. Mol. wt.: 406.3; M.f.: C19H17Cl2N3O3; Form: White to light beige crystals. M.p.: 78.6 ºC; V.p. 3.3x10-5 mPa (25 ºC). KOW: logP = 4.20 (25 ºC). Henry: 1.5x10-6 Pa m3 mol-1 (calc.) S.g./density: 1.40 (20 ºC). Solubility: In water 15 mg/l (25 ºC). In ethanol 330, acetone 610, toluene 490, n-hexane 3.4, n-octanol 95 (all in g/l, 25 ºC). Stability: Stable up to 150 ºC. Hydrolytically stable.

 

Biochemistry: Sterol demethylation inhibitor. Inhibits cell membrane ergosterol biosynthesis, stopping development of the fungus.

Mode of action: Systemic fungicide with preventive and curative action. Absorbed by the leaves, with acropetal and strong translaminar translocation.

Uses: Systemic fungicide with a novel broad-range activity protecting the yield and crop quality by foliar application or seed treatment. Provides long-lasting preventive and curative activity against Ascomycetes, Basidiomycetes and Deuteromycete,s including Alternaria, Ascochyta, Cercospora, Cercosporidium, Colletotrichum, Guignardia, Mycosphaerella, Phoma, Ramularia, Rhizoctonia, Septoria, Uncinula, Venturia spp., Erysiphaceae, Uredinales and several seed-borne pathogens. Used against disease complexes in grapes, pome fruit, stone fruit, potatoes, sugar beet, oilseed rape, banana, cereals, rice, soya beans, ornamentals and various vegetable crops, at 30-125 g/ha. Used as a seed treatment against a range of pathogens in wheat and barley, at 3-24 g/100 kg seed.

Phytotoxicity: In wheat, early foliar applications at growth stages 29-42 might cause, in certain circumstances, chlorotic spotting of leaves, but this has no effect on yield.

Formulation types: DS; EC; FS; SC; WG.

 

Oral: Acute oral LD50 for rats 1453, mice >2000 mg/kg.

Skin and eye: Acute percutaneous LD50 for rabbits >2010 mg/kg. Non-irritant to eyes and skin (rabbits). Non-sensitising to skin (guinea pigs).

Inhalation: LC50 (4 h) for rats 3300 mg/m3 air.

NOEL: (2 y) for rats 1.0 mg/kg b.w. daily; (1.5 y) for mice 4.7 mg/kg b.w. daily; (1 y) for dogs 3.4 mg/kg b.w. daily.

ADI: 0.01 mg/kg b.w.

Other: Not teratogenic or mutagenic.

Toxicity class: WHO (a.i.) III

EC hazard: (R22)

 

Birds: LD50 (9-11 d) for mallard ducks >2150 mg/kg. LC50 for bobwhite quail >4760, mallard ducks >5000 ppm.

Fish: LC50 (96 h) for rainbow trout 0.8, bluegill sunfish 1.2, sheepshead minnow 0.82 mg/l.

Daphnia: LC50 (48 h) 0.77 mg/l.

Algae: EC50 (72 h) for Scenedesmus subspicatus 1.2 mg/l.

Other aquatic spp.: EC50 (96 h) for Eastern oysters 0.45 mg/l; (14 d) for Lemna gibba 18.5 mg/l.

Bees: Non-toxic to honeybees; LD50 (oral) >187 ug/bee; LC50 (contact) >100 ug/bee.

Worms: LC50 for earthworms >610 mg/kg.

 

Animals: After oral administration, difenoconazole was rapidly eliminated practically to entirety, with urine and faeces. Residues in tissues were not significant and there was no evidence for accumulation.

Plants: Two routes of metabolism: one by a triazole route to triazolylalanine and triazolylacetic acid; the other by hydroxylation of the phenyl ring followed by conjugation.

Soil/Environment: Practically immobile in soil, strong adsorption to soil particles, low potential to leach below top soil layer. Soil dissipation rate is slow and dependent on application rate. DT50 for photolysis 145 d (natural sunlight).