The bacteria responsible for this disease infect plants near the soil line or on stems and roots, producing lumpy growths ranging from pea-size to baseball-size. Various plants are susceptible; check with your Cooperative Extension Office for a list. Besides deforming plants, the galls may cause serious damage by interrupting the flow of water and nutrients.
The problem often arrives in the garden via infected nursery stock; it can be transmitted when gardeners prune infected plants, then go on to prune others without disinfecting tools first. The bacteria may also enter a plant through wounds.
To control crown gall, look for resistant varieties and check plants for symptoms before buying them. If you have had crown gall in one garden location, don't plant susceptible new plants in the same area. Remove and destroy infected plants; be sure to disinfect tools when pruning.
There is no chemical control.