Infections with Botrytis cinerea cause serious damage in strawberry production. The infection starts already at blossom. For Botrytis control several treatments are necessary. After repeated treatments, chemical fungicides are highly at risk to loose efficacy due to the development of resistant strains of B. cinerea. A simple and effective measure for resistance management is the replacement of chemical fungicides with single side mechanisms by biocontrol agents containing antagonistic microorganisms. Aureobasidium pullulans used in Boni Protect forte has a strong potential to fulfill this mission. Its efficacy in the control of B. cinerea could be shown in two years trials in strawberries at two different locations in Germany and in a one year trial in Poland on raspberries. Spray strategies in which Boni Protect forte was used in alternation with chemical fungicides revealed comparable control of B. cinerea as the standard treatments with chemical fungicides.