Acidify soil with ammonium sulfate or sulfur. There are many types of galls that commonly occur on oak leaves. Leaf galls do not affect tree vigor and should be ignored. Also see MU publication G 7272 . Leaves in the upper crown become dull green, bronzed or scorched.
Defoliation begins soon after symptoms appear.
Green leaves also may drop. Brown to black streaks develop in sapwood, but they may be difficult to detect. Positive identification possible only by laboratory culture. In the red oak group, disease is almost always lethal. Species in the white oak group are somewhat resistant and sometimes recover on their own.