The bacterium enters the plant through wounds made during grafting, planting, or pruning. Often plants are infected in the nursery, and the disease develops later, after planting in the garden.
Symptoms are a gradual decline in plant health, often associated with the presence of spherical, woody growths at the crown or on stems. Initially, galls are white/cream color and turns brown/black later.
Galls have rough surfaces and may grow up to 6 inches in diameter. Diseased plants should be removed and destroyed. Galls may be at the crown or at wound sites well above the ground.
Galls also form on the roots indicating the presence of the bacterium in the soil. The pathogen can spread easily through contaminated soil, and pruning equipment.