The problem you're describing is oak leaf blister. This is a fungus disease, and while it causes the leaves to grow abnormally, oak leaf blister isn't going to kill the tree, nor will the disease get any worse for the rest of the year. It's too late to carry out control measures at this point in the year, but homeowners who are interested in a program for next year can check with the county Extension office for further information. Q. Patches of crusty greenish-gray growth are present on the bark of my azaleas, camellias, and some of my plum and apple trees. The appearance, however, is that of a single plant.
Homeowners often become concerned when lichens showup on plants and think they're causing damage.
Lichens most often appear on plants that for some reason are in a poor or declining condition. Why lichens pick-out weak plants as colonization sites isn't fully understood, but for whatever reason, such plants support lichen growth and it's easy to understand why home landscapers think these harmless organisms are responsible for poor plant growth. Q. Yesterday, I noticed that many leaves on my azaleas have become thickened and formed whitish, fleshy gall-like growths. These galls detract from the beauty of my azalea planting. These growths result from infection by the fungus which causes a disease know as azalea leaf gall.