Diseases of grape (
Crown gall
Crown gall of grape is caused by the bacterium Agrobacterium tumefaciens. The bacterium causes galls to form just below or at the soil line on the main trunk or roots. The young galls are small and smooth, while older galls become large and coarse, eventually becoming cracked, brittle and dry. If gall formation is slight, the plant may not be adversely affected and have no loss of vigor. Severe infections, especially on young plants, can cause plant death. Plants are infected only through wounds sites, and freeze damage and pruning wounds are common sites of infection.
Agrobacterium tumefaciens is systemic in woody grape tissue and can be carried in dormant planting material. It is very important to plant clean, non-infected, planting material into non-infested soils. Once vines are infected, there is no control. Other hosts include roses, many fruit trees and pyracantha.
Other photos and information can be found at:
http://www.ipm.ucdavis.edu/PMG/r302100911.html
September 20, 2002