A process for combating fungi, wherein a fungicidally effective amount of a substituted imidazolylmethyloxirane or of a substituted imidazolylpropene of the formula I ##STR20## where R.sup.1 and R.sup.2 are identical or different and each is C.sub.1 -C.sub.8 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl, C.sub.5 -C.sub.8 -cycloalkenyl, tetrahydropyranyl, norbornyl, pyridyl, naphthyl, biphenyl or phenyl, each of which is unsubstituted or mono- to trisubstituted by halogen, nitro, phenoxy, amino, alkyl, alkoxy or haloalkyl, each of 1 to 4 carbon atoms,
- D is oxygen or a single bond,
- E is H, F, Cl or Br,
- X, Y and Z are identical or different and each is hydrogen or C.sub.1 -C.sub.3 -alkyl, X, Y and Z not simultaneously being hydrogen, or an acid addition salt or metal complex thereof tolerated by plants, is allowed to act on the fungi or the materials, areas, plants or seed threatened by fungus attack.