Difenoconazole is a broad-spectrum triazole fungicide that inhibits ergosterol biosynthesisviainhibition of the cytochrome P450-dependent 14α-demethylation of lanosterol, which results in disruption of the fungal cell membrane and cell death.^1,2It inhibits the growth ofF. graminearumisolatesin vitro(EC₅₀s = 1.69-19.6 mg/L for mycelial growth).²It also inhibits growth ofA. sonali,F. fulva,B. cinerea, andR. solani(EC₅₀s = 0.131, 0.069, 0.297, and 0.252 mg/L, respectively).³Difenoconazole reduces germtube growth ofA. caricae, the mold responsible for black spot in papaya plants (EC₅₀= 2 ppm).⁴It exhibits acute aquatic toxicity, reducing growth ofS. obliquusalgae (EC₅₀= 1.338 μg/ml) and decreasing survival ofD. magna(LD₅₀= 0.298 μg/ml).³Difenoconazole is also lethal to zebrafish (D. rerio) embryos, larvae, and adults (LC₅₀s = 2.34, 1.17, and 1.45 mg/L, respectively).⁵At sub-LC₅₀concentrations, difenoconazole induces pericardial and yolk sac edema in zebrafish embryos, body blackening and slowed heart rate in larvae, and decreased body weight and length in adults.

1.Zarn, J.A., BrÜschweiler, B.J., and Schlatter, J.R.Azole fungicides affect mammalian steroidogenesis by inhibiting sterol 14 α-demethylase and aromataseEnviron. Health Perspect.111(3)255-261(2003) 2.Rekanovi?, E., Mihajlovi?, M., and Poto?nik, I.In vitro sensitivity of Fusarium graminearum (schwabe) to difenoconazole, prothioconazole and thiophanate-methylPestic. Phytomed.25(4)325-333(2010) 3.Dong, F., Li, J., Chankvetadze, B., et al.Chiral triazole fungicide difenoconazole: Absolute stereochemistry, stereoselective bioactivity, aquatic toxicity, and environmental behavior in vegetables and soilEnviron. Sci. Technol.47(7)3386-3394(2013) 4.Vawdrey, L.L., Grice, K.R.E., and Westerhuis, D.Field and laboratory evaluations of fungicides for the control of brown spot (Corynespora cassiicola) and black spot (Asperisporium caricae) of papaya in far north Queensland, AustraliaAus. Plant Path.37(6)552-558(2008) 5.Mu, X., Pang, S., Sun, X., et al.Evaluation of acute and developmental effects of difenoconazole via multiple stage zebrafish assaysEnviron. Pollut.175(2013)147-157(2013)