Crown gall tumors collected from naturally infected plants of 7 grapevine varieties were analysed for the presence of opines. Eighty-five of the tested 90 samples contained known Agrobacterium vitis-induced opines. Octopine was the most common, it was found in 50 samples. Twentyeight crown galls contained nopaline and 8 were vitopine positive. There was only one tumor that contained two opines,...