Crown gall disease of grapevine, caused by the bacterial pathogen Agrobacterium tumefaciens biovar 3, is of increasing importance in Australia and is associated with the more widespread use of specific rootstocks. The bacterium survives systemically in grapevines and, in this investigation, was detected in the vascular system of a range of rootstock and scion propagation material. Levels of contamination in two of the most useful rootstocks, K51–40 and Ramsey, were very high (50–100% of cuttings infested), low or undetectable in other rootstocks and moderate (10–40% of cuttings infested) in all scions tested, except Sauvignon Blanc. Contamination was not associated with any one source of propagation material. Two detection assays were found to be comparable in sensitivity. A monoclonal antibody to biovar 3, developed in New York State, was extremely reliable for identifying strains from cuttings. There was excellent correlation between strains positive for antibody reaction and for diagnostic characteristics associated with biovar 3. Most biovar 3 strains isolated from the propagation material were tumorigenic.