Grape phylloxera (Daktulosphaira vitifoliae Fitch) can vector root-pathogenic fungi when they feed, allowing the fungi to girdle the roots and eventually cause vine death. For many years, phylloxera-resistant rootstocks have been used to prevent vine death. Previous experiments have determined levels of fungal resistance possessed by phylloxera-resistant rootstocks via excised root and greenhouse experiments, but not on field plants.  We conducted a field experiment to determine susceptibility of whole field plants of various resistant rootstocks to infection by Fusarium fungi.  Young grapevines representing eight different rootstocks were chosen from an experimental vineyard in Davis, California.  Vines were exposed to low and high virulence Fusarium isolates in October 2002 and allowed to overwinter. We found that all rootstocks were susceptible to infection, regardless of their level of resistance to grape phylloxera.