oak tree leaves

Asked September 27, 2017, 3:47 PM EDT

Hi, I have a 300-year old oak tree. I have notice that the leaves dropping this fall have these bumps attached to the back of the leaves (see pictures). This may have occurred in the past, I just never noticed. Is this infestation something to be concerned about? We try to take care of this tree (trimmed periodically and professionally fertilized). Do I ignore this or should something be done and if so what? Thank you.

Baltimore County Maryland

1 Response

The bumps you see on the back of the leaves are called galls. These are often caused by insects but also may be initiated by mites, fungi, or bacteria. There are many types of galls. Take a look at our web page about them. https://extension.umd.edu/hgic/shade-tree-galls There is really nothing you need to do. This is quite normal -- especially on white oaks.