Gouty Oak Gall
A Gouty Oak Gall is an irregular plant growth that can grow up to two inches in diameter. Although the galls are unsightly, they usually don’t dramatically affect the host tree’s health.
• Scarlet oak
• Red oak
• Pin oak
• Black oak
Tiny wasps, called Gouty Oak Gall wasps, cause the formation of galls on twigs and stems of trees as a part of their lifecycle. In the spring, the female wasp lays its eggs within expanding plant tissue. The tree reacts to the chemicals from the wasp and forms the gall around the eggs.
The gall grows only briefly, and then stops to confine the larvae within. The gall is solid and woody with multiple larval chambers in the center. The inner gall tissue nourishes the wasp larvae. The wasps will develop within the gall until they emerge two years or later.
When the galls heavily infest a tree, their weight may cause the branches to droop and possibly die. A heavily infested tree is more susceptible to storm damage.
Once a gall begins to develop, it is almost impossible to stop or reverse. Currently, there is little or no effective measure of control. Pesticides are not effective because the insects are confined within the galls. Affected braches can be manually pruned off and destroyed. Although the galls are unattractive, they will probably not kill the tree and usually natural controls will reduce the population in succeeding years.