Gouty Oak Gall is caused by wasps
This twig disease has historically been disregarded as a cosmetic tree problem. Large growths develop on the stems of oak trees and cut off the flow of nutrients out to the tip of the twig. Oak trees have so many branches that a few galls have no effect on the overall health of the tree. However, in recent years this gall has become more prolific and if an infestation is sever, the entire tree can be killed.
What trees and shrubs are affected?
- Oak trees in the red oak group
- Pin Oak
- Shingle Oak
- Red Oak
- Black Oak
Tiny wasps lay eggs on both the leaves and the twigs of oak trees. The gales encapsulate the wasp eggs. Adult wasps emerge from the galls and begin the cycle all over again. At first, the galls are sparse throughout the tree. As more and more lifecycles of wasps re-infect the tree, areas of the tree can be completely covered with gall formations. Wasps do not tend to travel far from the host tree. Infestation usually occurs on one tree and slowly spreads to adjacent trees.
Symptoms
- The wound associate with the wasp causes the tree to form woody masses around twigs and branches. These galls vary is size but average about 2" in diameter.
- Gouty oak gall is very similar to horned oak gall. However, horned oak gall has little protruding "horns" all around the woody mass.
Due to the complex life cycle of the wasp, it is very difficult to control gouty/horned oak gall.
- If infestation is minimal, consider tolerating the galls and increasing the health and vigor of the tree. Water regularly, mulch and consider fertilizing. If possible, prune off infected branches. This will minimize the number of wasps emerging and prevent more injury.
- Insecticide applications have not been successful for the control of gouty or horned oak gall.
