Crown Gall Formation in a Diverse Collection of Vitis Genotypes Inoculated With Agrobacterium vitis

Relative levels of crown gall susceptibility were determined in 43 Vitis genotypes by inoculating with a diverse set of Agrobacterium vitis strains and measuring gall size and the proportion of sites forming galls. No genotype was immune to crown gall. In different genotypes, galls formed at 10% to 100% of inoculated sites, and mean gall size ranged from 1.0 to 12 mm when averaged across strains. Significant strain x genotype interactions were observed. Vitis amurensis was especially sensitive to the limited host range strain AG57. Commonly used rootstocks, 3309C, T5C, Riparia Gloire, and 101-14 Mgt, were among the most crown gall resistant genotypes. Vitis flexuosa, V. piasezkii , and V. amurensis , reported not to form galls in an earlier study, were resistant but not immune. Rootstocks 110R, 420A, and Dogridge were highly susceptible.