The present invention relates to a method for controlling phytopathogenic fungi of the genus Phoma spp. and Verticillium spp. comprising applying Coniothyrium minitans strain CON/M/91-08 or a mutant having all identifying characteristics of the respective strain in an effective amount to the root system of a plant, to harvest residues or to the soil on which a crop plant grows or is intended to grow. Also disclosed is the use of said strain for controlling phytopathogenic fungi of the genus Phoma spp. and Verticillium spp.