The present invention relates to the use of strobilurin type compounds of formula I and the N-oxides and the salts thereof for combating phytopathogenic fungi containing an amino acid substitution F129L in the mitochondrial cytochrome b protein (also referred to as F129L mutation in the mitochondrial cytochrome b gene) conferring resistance to Qo inhibitors, and to methods for combating such fungi. The invention also relates to novel compounds, processes for preparing these compounds, to compositions comprising at least one such compound, and to seeds coated with at least one such compound.