Resistance to fungicides which inhibit ergosterol biosynthesis in laboratory strains of Botrytis cinerea and Ustilago maydis

The strains of Botrytis cinerea or Ustilago maydis selected on fenarimol, triarimol, or triadimefon were also resistant to the other inhibitors of sterol C‐14 demethylation; the sterol composition of the strains was normal. Among the isolates of U. maydis resistant to dodemorph, fenpropidin, fenpropimorph and tridemorph, some were resistant to the 15‐azasteroid A 25822B and did not contain ergosterol. The other strains remained sensitive to A 25822B and had a normal sterol composition. All the resistant isolates and the wild‐type were inhibited to the same extent by nystatin and pimaricin.