Oak Gall – Oak Scale

Oak galls come from a species of dinimutive wasps that are known to infest oak trees. Most of the times, these galls, or abnormal growths or inflammation on twigs or foliage, have no significant effects on the health of the tree. However, if they appear heavily on the twigs and branches of a tree, injury or death can occur to the tree.

Galls form on an oak tree when the wasp places a stimulus into the plant’s system. In the case of the horned gall wasp, the gall that forms has several horns on it. Eventually, an adult gall wasp will come out of each of the horns, although it takes them at least two years to reach maturity. While the young insect is growing, it takes nutrients from the trees, which is why heavy infestations can threaten the health of the tree.

We have encountered quite a few cases of oak galls in the Bay Area. Generally, we suggest taking and destroying any leaves that show signs of broad infestation. If you notice the galls on branches or twigs, prune and get rid of the infested areas if possible. If you can do this while they are still small, they have not yet had a chance to start utilizing plant nutrients.

If you notice some of these unusual growths on your tree, give us a call or fill out our contact form. Our arborists are trained to handle oak galls, and we are a leader in the Santa Cruz area when it comes to keeping trees thriving and healthy. We offer complete consultation for our clients, which means you receive a complete analysis of all of your trees, as well as a complete plan for remedying any infections or threats. Many tree diseases do not show outward signs until it is too late to save the tree, so let our trained staff come and look for more subtle signs of these conditions.