Oak Leaf Blister
May 6, 2013
In early spring, small, rough spots appear as the oak leaves grow. The spots are pale green and thicker than the normal leaf tissue. As the spots age, they will turn brown. Affected leaves with numerous spots will typically fall from the tree. If the tree is well-established, and experiences a heavy defoliation before mid-summer, it may push out new leaves in late-summer or fall. If the defoliation happens in late summer or early fall, then impact on the tree's vigor is lessened.
Often, no treatment is recommended. Due to the nature of the fungus and how it affects trees, it can often be difficult to treat. You should have a certified arborist assess your tree's condition if it has the disease. If you have newly planted specimens that have been previously affected, they should be treated with a protective fungicide when buds begin to swell in early spring.
Posted: May 6, 2013