Agrobacterium tumefaciens 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.
Galls have rough surfaces and may grow up to 6 inches in diameter. Diseased plants should be removed and destroyed.