Difenoconazole (Synonyms: CGA 169374)

Difenoconazole is a broad-spectrum triazole fungicide that inhibits ergosterol biosynthesis via inhibition of the cytochrome P450-dependent 14α-demethylation of lanosterol, which results in disruption of the fungal cell membrane and cell death.^1,2 It inhibits the growth of F. graminearum isolates in vitro (EC₅₀s = 1.69-19.6 mg/L for mycelial growth).² It also inhibits growth of A. sonali, F. fulva, B. cinerea, and R. solani (EC₅₀s = 0.131, 0.069, 0.297, and 0.252 mg/L, respectively).³ Difenoconazole reduces germtube growth of A. caricae, the mold responsible for black spot in papaya plants (EC₅₀ = 2 ppm).⁴ It exhibits acute aquatic toxicity, reducing growth of S. obliquus algae (EC₅₀ = 1.338 μg/ml) and decreasing survival of D. magna (LD₅₀ = 0.298 μg/ml).³ Difenoconazole is also lethal to zebrafish (D. rerio) embryos, larvae, and adults (LC₅₀s = 2.34, 1.17, and 1.45 mg/L, respectively).⁵ At sub-LC₅₀ concentrations, 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)