Bacterial gummosis is caused by Pseudomonas syringae one of the major troubles encountered in cherry and apricot orchards. The same disease may sometimes attack peaches, plums and prunes. The tendency toward gumming is common in all stone fruit trees. The gumming is due to formation of cankers (depressed areas in the bark, which darken with age). A gummy substance often exudes from cankers on fruiting and flowering stone fruits (this symptom is referred to as “gummosis”). If cankers continue to enlarge, they may girdle the stem and subsequently kill a branch or the entire plant. IF the outer tissues of the canker area are cut away, the tissue underneath shows a reddish brown discoloration. This discoloration may also occur as vertical streaks in the vascular tissue.