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. The bacterium which causes Pseudomonas blight overwinters in infected bark tissue or on the surface of bud scales or twigs. The pathogen may also predispose plant tissue to early fall or late spring frost and invades damaged tissue following freeze injury. Once inside plant tissue, the bacterium produces a toxin that is translocated upward in the water-conducting system to newly developing leaves.