Diclobutrazol is the active ingredient of a broad-spectrum systemic fungicide for use on cereals. Diclobutrazol sprays appear promising for the control of coffee rust, apple mildew and scab, grape powdery mildew and various other crop diseases. Diclobutrazol has a systemic action and is translocated mainly acropetally. It eradicative action, increased by vapour effect, is very strong. Diclobutrazol is of low toxicity to mammals and other animals. It is also of low toxicity to birds, fish and invertebrates. Diclobutrazol inhibited spore germination and mycelia growth of a wide range of fungi. Stereoselective inhibition of human CYP3A4 and Candida albicans CYP51 was observed with enantiomers of the azole antifungal compound diclobutrazol. The RR(+) configuration at its asymmetric carbon center was most active.