Bitertanol is a broad-spectrum triazole fungicide that is active against a variety of fungi, including V. inaequalis and V. pirina, which are responsible for apple and pear scab, respectively, as well as S. mors-uvae and P. ribis, which are responsible for American gooseberry mildew and leaf spot in black currants, respectively.1 It is active against isolates of V. inaequalis (MICs = 0.6 and 1 µg/ml) but repeated use leads to resistance and cross-resistance (MICs = 9.8-13 µg/ml for bitertanol-resistant isolates).2 Bitertanol inhibits the cytochrome P450 (CYP450) isoform CYP3A4 (IC50 = 2.74 µM) and inhibits androgenic activity induced by the androgen receptor agonist DHT in a yeast two-hybrid assay (IC50 = 79.85 µM).3 In rats, bitertanol (10-300 mg/kg, i.p.) increases operant responding on one- and five-minute fixed interval schedules with no effect on motor activity.4
1.Birch, P.A., Rose, P.W., and Wainwright, A.A broad spectrum fungicide of the triazole group for use in pome and bush fruitBrit. Crop Prot. Conf. - Pests and Dis., Proc.11(2)545-554(1981) 2.Hildebrand, P.D., Lockhart, C.L., Newberry, R.J., et al.Resistance of Venturia inaequalis to bitertanol and other demethylation-inhibiting fungicidesCan. J. Plant Path.10(4)311-316(1988) 3.Lv, X., Pan, L., Wang, J., et al.Effects of triazole fungicides on androgenic disruption and CYP3A4 enzyme activityEnviron. Pollut.222(2016)504-512(2017) 4.Allen, A.R., and MacPhail, R.C.Bitertanol, a triazole fungicide, increases operant responding but not motor activityNeurotoxicol. Teratol.15(4)237-242(1993)