Agrobacterium vitis is the causal agent of grapevine crown gall, an economically important disease in cold climate viticulture regions. The disease occurs frequently in Okanagan vineyards and limits grape production and lifespan of vineyards. The pathogen spreads either through infected planting material from grapevine nurseries or infects healthy grapevines planted in soil harboring A. vitis. Entry of bacteria occurs through wounds in the grapevine trunk or canes due to winter freezing or mechanical injuries. In an earlier study we developed a rapid and sensitive technique to quantify A. vitis in grapevine planting material. This allows us to screen grapevines that have been purchased by the grape industry before planting into a vineyard. To prevent infection of healthy planting material from A. vitis residing in soil, a second technique to quantify the A. vitis soil population is urgently needed. Here we propose the development of a technique to quantify A. vitis from virgin and vineyard soil. We will also determine the threshold concentration of A. vitis in soil that will result in the development of crown gall disease in a greenhouse experiment. This will lead to valuable information for growers to determine the risk of infection when a new vineyard is established. Our techniques will form the base for the development of a biocontrol for crown gall disease in future projects.