The invention concerns the application of compositions of micro-organisms in biological control of vin crptogamic diseases. Said composition comprises a mixture of at least one bacterium and at least one yeast, the bacterium or bacteria and the yeast(s) being non-toxic for the plant. The invention also concerns bacterial and yeast strains, as well as biofungicide formulations containing an efficient amount of at least one composition of micro-organisms including in mixture at least one bacterium and one yeast, the bacterium or bacteria and the yeast(s) being non-toxic for the plant, and a composition of filamentous fungi, in particular of the genus Pichia, Pythium, Trichoderma, Gliocladium, Ampelomyces, Talaromyces, Epicococcum, combined with an inert carrier. The invention is useful for treating cryptogamic plant diseases, in particular crop plants and vine.