In general, affected plants are more susceptible to adverse environmental conditions, especially winter injury. The major symptom of crown gall is the fleshy galls. Large galls may develop rapidly and completely girdle young vines in one season. Galled vines frequently produce inferior shoot growth, and portions of the vine above the galls may die. Current-season galls are first apparent in early summer as white, fleshy, callus growth.
Galls turn brown by late summer and in the fall become dry and corky.
The crown gall bacterium is systemically present in the vast majority of grape vines, but seldom causes disease unless the vine in injured. The disease organism is the soil-borne bacterium, Agrobacterium tumefaciens . The bacterium survives for long periods of time in soil, within galls and within infested vines. A fresh wound is required for gall formation to start in the grapevine. Because the bacterium lives in the soil it cannot be controlled by chemical sprays.