Cankers are among the most destructive and hard-to-manage problems of woody plants. The term "canker" is used to describe a killed or blistered area in and on the bark, the branch or trunk of an infected tree. Dozens of species of fungi cause canker diseases including Scleroderris, Fusiform, pitch cankers and Cytospora.
Most cankers are displayed as noticeable diseased areas that are sunken and discolored. Many times resin is oozing from the branches or trunk at the canker location. For a specific diagnosis, a sample that includes the canker is usually necessary.
Prevention is generally easier than trying to deal with an infected tree. The best way to avoid canker diseases is to keep trees as stress free and healthy as possible. Promoting good air circulation by proper spacing, avoiding drought stress by watering when necessary, planting on appropriate sites, and mulching can help maintain tree vigor. Keeping your tree healthy can minimize the harmful effects of this disease. Take This Tree Health Test.
There are very few control options and they will only slow the disease progression. Pruning out infected branches should be done during dry weather. If the main trunk is infected, everything above the canker will probably die, since the fungus can eventually girdle the trunk, disrupting water flow. Cankers on tree trunks are not good news.