Disclosed is a Saccharomyces cerevisiae strain, characterized in that it is selected from strain No. I-3936 deposited on March 4th 2008 at the CNCM, strain No. I-3937 deposited on March 4th 2008 at the CNCM, strain No. I-3938 deposited on March 4th 2008 at the CNCM, and strain No. I-3939 deposited on March 4th 2008 at the CNCM. Also disclosed is a phytosanitary composition comprising said S.cerevisiae strains.