Oak Leaf Blister
Q: Our large oak tree’s leaves are dying. Can you tell us why and what should we do?
A: This is a disease called Oak leaf Blister.
It is common when we have cool, wet springs. Diseased areas grow slowly but the symptoms are very visible in midsummer.
There is not much you can do about it. Generally speaking, it will not harm trees as long as they don’t suffer from drought at the time the disease attacks them.
See Oak Leaf Blister