Fungi or something on my oak leafs.
Should I do anything about it? I am in Lake Ann next to Traverse city, northwest side of MI, 10 of the coast.
Benzie County Michigan oak galls
What you are observing is a type of oak gall. Although it may be odd looking and unsightly, this will not kill your oak. It's actually an insect's larvae inside that are developing.
Here is an extension resource that explains them more: https://web.extension.illinois.edu/ccgms/downloads/42438.pdf
thanks for your inquiry