Fungicide
FRAC  3; DMI: triazole



NOMENCLATURE
Common name difenoconazole (BSI, draft E-ISO)
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  Development codes CGA 169 374 (Ciba-Geigy)

PHYSICAL CHEMISTRY
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. 3.3 × 10^-5 mPa (25 ºC)  K_OW logP = 4.20 (25 ºC)  Henry 1.5 × 10^-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.

APPLICATIONS
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.

ANALYSIS
Residue determination by glc. Details from Syngenta.

MAMMALIAN TOXICOLOGY
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 ³3300 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) 

ECOTOXICOLOGY
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 mg/bee; LC₅₀ (contact) >100 mg/bee.  Worms LC₅₀ for earthworms >610 mg/kg.

ENVIRONMENTAL FATE
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).