Galls On My Oak

Q: I hope you are doing well. What do you think is wrong with my tree? I think it is a sand post oak – but maybe I’m wrong – and he looks like he has some systemic problem going on here.


A. My best guess is one of the many leaf galls common to oak trees. Leaf galls are usually more of a cosmetic problem rather than a health crisis and do not warrant chemical control. The gall itself is primarily made up of plant tissue that forms when insects lay eggs inside the leaf tissue and either the adult or the developing young insects secrete a growth-stimulating substance. Each insect causes a very characteristic gall. Most leaf galls are nothing to be concerned about from a plant health standpoint, although they may be unsightly. However, once the gall appears, the appearance of the current growth cannot be remedied. Some of the most common landscape plants that develop galls include oaks, maples, hackberries, and roses.

More information regarding galls on trees is available in Purdue Extension publication E-56 at

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