Cylindrocarpon black foot is a major disease of grapevines worldwide. Grapevine rootstocks have been shown to vary in their susceptibility to C. destructans, with Riparia Gloire (RG) having low susceptibility and 101-14 moderate to high susceptibility (1). The population and functionality of rhizosphere bacteria associated with these two rootstock varieties was assessed to determine whether the rootstocks differentially select bacterial populations with the potential to suppress the pathogen.