More than 600 plant species in over 90 families are susceptible, although relatively few species sustain significant damage. Some of the common hosts include apple, blackberry, cherry, euonymus, forsythia, peach, pear, plum, poplar, raspberry, rhododendron, rose, and willow. Galls form on roots and stems, especially at the root collar, or root crown.
Aerial galls are common on such highly susceptible plants as poplar, rose, willow, and euonymus.
Young plants with numerous galls tend to be stunted and predisposed to drought damage or winter injury. Floral display or fruit production may be suppressed. Damage is most severe when galls encircle the root crown, but few plants are killed by crown gall alone. Severely diseased plants are subject to attack by secondary pathogens that enter through decaying galls. Crown gall bacteria are dispersed in soil or irrigation water, on horticultural implements, and on or within plants.