The National Clonal Germplasm Repository (NCGR) in Davis, California (CA) maintains the United States collection of warm-climate grapes in a field genebank in Winters, CA. This collection includes numerous accessions that are highly susceptible to Pierce's disease (PD) as well as many PD-tolerant accessions that are native to the Southeastern United States. If the glassy-winged sharpshooter became established in the Winters area, then reservoirs of the PD causal agent Xylella fastidiosa (Xf) within the collection Would provide abundant inoculum for the rapid spread of Xf throughout the genebank. Therefore, PCR screening for Xf was conducted using a primer pair that is genome sequence specific to Xf and is reported to provide a high degree of sensitivity and specificity to all Xf strains that have been tested. Basal leaf petioles were collected from 60 different accessions in the NCGR representing a broad cross section of taxa and periods of time since collection in the region where Xf is endemic. Only Chardonnay previously inoculated was found positive for presence of Xf. It is concluded that NCGR grape accessions collected as budwood in the southeastern United States, where Xf and PD are endemic, are not a significant reservoir of Xf. There appears to be no reason for removing these vines if GWSS Populations become established in the area surrounding the genebank.