On Callery pear and lilac, symptoms closely resemble those of another bacterial disease called fireblight. Affected leaves first develop light yellow lesions. These lesions eventually expand, become water-soaked, and turn black. Black streaks often develop along the midrib and veins of leaves. In severe cases, the disease will girdle new shoot growth and cause a rapid wilting and blackening of tissue beyond the canker margin.
Dead shoots bend slightly and resemble a shepherd's crook.
On stone fruits, particularly apricot and cherry, the bacterium will kill buds in winter and blossoms in early spring. Large cankers may also form on the branches and trunks or winter-damaged trees. Stem cankers are slightly sunken and often have extensive gummosis. The liquid which exudes from the canker may have a sour or foul smell. Multiple trunk or scaffold branch cankers can result in tree mortality.