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FAQs About Horned Oak Galls

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Finding a spiky, enlarged growth on your oak tree may be alarming at first. After some research, you might find that what you're looking at is a horned oak gall. Knowing what it is can make you feel a bit more comfortable, but chances are, you still have some questions. Discover the answers below.

What causes horned oak galls?

Since so many tree problems are caused by fungi, people often assume that horned oak galls are also caused by fungi. But this is not the case. They are actually one of several tree problems caused by insects. A species of wasp chews its way into some of the tree's wood and lays its eggs beneath the bark. The eggs swell and eventually develop into white, slug-like larvae, and as this occurs, the oak tree develops the bulbous formations you're seeing. It can take a year or more for a horned oak gall to go from its small, early stage to its full size.

Are horned oak galls harmful to your oak tree?

A few of these galls won't cause all that much damage, but a lot of the galls can. They weaken the oak tree's wood and tissues, and they make the branches more prone to breakage. Large galls can inhibit the flow of water and nutrients to the outermost branches and leaves, which can lead to leaf drop and branch death,

What do you need to do about oak galls?

If there are only a few horned oak galls, you can generally just leave them in place. However, if their appearance bothers you, then a tree care expert can come to trim away the branches that are most affected. 

If your tree has a lot of horned oak galls, then you should absolutely have a tree care company come out. They can inject the tree with insecticides. These won't cure the galls immediately, but they can help keep additional wasps from arriving and laying their eggs. Your tree may need several injections, spaced a few months apart. The tree care company can also prune away any branches that are badly damaged, at risk of falling, or really ugly. 

Now that you know a little more about oak galls, you can be more prepared to treat your tree and manage this condition. It's often not as bad as it looked, and the key issue to worry about tends to be the tree's appearance.