We are getting quite a few inquiries about oak leaves showing signs of malformed growth with a blister like appearance and browning of the affected areas. This spring’s cool and rainy weather seems to have set the stage for a significant amount of damage from the oak leaf blister fungus.
The disease infects the emerging and developing foliage in spring and as the weather heats up tends to no longer affect new growth.
For more info see our previous blog post.
Also see this info sheet from the AgriLife Extension State Plant Clinic.