Tree Branch Fungus

Disease Identification

• Fungal infections on trees can lead to a condition known as cankers. Cankers are the result of one or more species of fungi growing between the tree bark and the wood, eventually killing live tree tissues. Canker diseases are the most destructive, as well as the most hard-to-control, problem of woody plants.

Symptoms

• Symptoms of cankers differ with the causal agent and tree type. Damage on thin-barked tree is characterized with sunken, elongated, depressed areas with well-defined borders. Unaffected outer bark is light colored, while the infected tree tissue is brown, black or red. Affected bark is water-soaked or resinous. Cankers are not easy to locate on thick-barked trees. The fungus produces fruiting bodies in the form of pepper-like, black spots to red clusters within the infected area.

Damage

• Cankers weaken the wood at the site of infection and the resulting decay causes branches to collapse. Infection sites become an entry point for other often potentially lethal tree diseases resulting from fungal and bacterial infections or pest infestations. Branches often remain attached to the tree with wilting foliage. Vigorously growing trees react to the infection with the growth of calluses or rolled plant tissues around the infected patches.

Control

• One of the best ways to deal with branch fungi-like cankers is to keep them from occurring in the first place. Keep trees in good health with adequate water, and fertilize between late fall to early spring to heighten their defense against infection. Make sure the tree variety is well adapted to local growing conditions. Carve out the cankers from the larger affected branches to minimize risk of spread. Prune smaller branches entirely from the tree, making the cut 4 inches below the infested site. Fungicides are generally not effective in canker control.