Fire blight caused by the gram-negative bacterium, Erwinia amylovora, is a major disease of several important fruit crop plants, such as apple and pear. Conventional methods to fight fire blight are ecologically and medically problematic since these methods are based on applying antibiotics to fruit trees. Our novel approach to deciminate the pathogen during its infection cycle is based on a better understanding of quorum sensing mechanisms in E. amylovora. It is known that virulence determinants of other pathogens are often under quorum sensing control. Consequently, a dissection of the components and genes required for cell density dependent gene expression might help to develop novel strategies to fight fire blight in the field. The research is cooperating on this topic with the laboratory of Prof. Dr. Klaus Geider at the Julius Kühn Institute Dossenheim based on support from the Bundesanstalt für Landwirtschaft und Ernährung (BLE).