DNA samples prepared from 15 Agrobacterium vitis and one A. tumefaciens strains were tested in polymerase chain reaction with 4 primer pairs. The pTiC58 virC specific primers did not detect any A. vitis, while the polygalacturonase specific primers resulted in positive reactions with all grapevine strains. Octopine and nopaline strains could be distinguished from vitopine strains by virE2 specific primers. Like for other bacterial species Triton X-100 with sodium-azide strongly increased the sensitivity of detection of A. vitis. Fourty-six colonies were isolated on a tartrate medium from grapevine bleeding sap collected from galled and symptomless Vitis vinifera cv. Cabernet Sauvignon and Riesling plants. Fourteen of them were identified by PCR as A. vitis, 11 of which proved to be pathogenic. Analysis of bleeding sap for A. vitis may become a useful diagnostic method for selection of healthy plants.
