Oak Leaf Blister | Atlanta, Georgia
Oak Leaf Blister | Signs and Symptoms
Oak leaf blister or Taphrina blister, caused by the fungus Taphrina caerulescens is a common disease affecting many species of oaks. Members of the red oak group are particularly susceptible to infection. Disease development is favored by cool, wet springs and, in years when such conditions occur, noticeable leaf deformity results. White oaks are rarely infected, even in years with cool, wet springs. Heavy infections of red oaks impair the trees ability to effectively create sugars through photosythesis.
Symptoms appear in early summer as yellow, blisterlike, circular, raised areas, 1/16 to 1/2 inch in diameter. The blisters are scattered over the upper leaf surface with corresponding gray depressions on the lower surface. They turn from yellow to reddish brown with age. Several blisters may merge and cause the leaves to curl.
This disease does not pose an emient threat to tree health but over time can weaken the tree by interupting the normal photosynthetic process. In most cases, a single pesticide application in early spring just before the buds begin to swell will effectively manage this disease. Fungicides will not be effective if applied after bud break. Homeowners are strongly discouraged from trying to treat large landscape trees. If treatment of large specimens is required, consider hiring a professional applicator. For small specimens, if needed, several pesticides containing the active ingredient chlorothalonil may be available for this use. Some products registered for managing this pest for home garden use in Atlanta, Georgia include: Ortho Max Garden Disease Control Concentrate, Bonide Fungonil Multipurpose Fungicide Concentrate; Fruit Tree, Vegetable & Ornamental Fungicide (Monterey); and Gardentech Daconil Fungicide Concentrate. Additional home garden products may be available. For more information please see Cornell University Plant Clinic Fact SheetArborist Evaluations