Effects of sterol biosynthesis inhibitor fungicides on growth and sterol composition of Ustilago maydis, Botrytis cinerea and Pyrenophora teres

The effects of the sterol biosynthesis inhibitor (SBI) fungicides fenarimol, fenpropimorph, imazalil, prochloraz, propiconazole and triadimenol on growth and sterol composition of Ustilago maydis, Botrytis cinerea and Pyrenophora teres, grown from spores or sporidia in liquid culture, were determined. Growth of U. maydis was only slightly inhibited by SBI fungicides at concentrations which caused considerable changes in both sterol content and composition. Conversely, in B. cinerea and P. teres, growth was strongly inhibited under conditions where ergosterol was still the predominant sterol, suggesting that, in these two fungi, growth may be more sensitive to SBI fungicides than overall sterol production. Demethylase inhibitor fungicides behaved as a homogeneous group in their effects on growth and on sterol profiles of the three fungi studied.