As they enlarge, the galls become woody with a rough and irregular surface.
Aerial galls can develop but most are found at or just below the soil line.
Galls range from pea-size to larger than 1 foot in diameter. Crown gall is worldwide in occurrence, attacking 140 plant genera in 60 different families. Plants most commonly damaged in Texas by crown gall are pecan, peach, blackberry, grape, apple, pear, willow, pyracantha, euonymus, rose, fig, and crabapple. Crown gall bacteria infect plants through wounds, such as those arising from cultivation, transplanting, wind damage, insect injury, etc. Wounds that have healed beyond a certain point are no longer susceptible to invasion.