The present invention relates to the use of strobilurine type compounds of formula I and the N-oxides and the salts thereof for combating phytopathogenic fungi containing a 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, to plant health applications, and to seeds coated with at least one such compound.