Oak Leaf Blister Theresa Badurek, Urban Horticulture Extension Agent It’s that time of year again, the leaves are green, the flowers are blooming, the birds are singing, the oak leaves are blistering. Ah spring! Wait a minute‐ oak leaves blistering? Yes, this is a common sight in the spring. Oak leaf blister (Taphrina caerulescens) is a common fungal leaf disease on oaks in Florida. It can affect any oak, but it seems more prevalent on laurel oak. This is a fungal disease that is more prominent after cool wet weather. The spores of this fungus infect newer leaves and cause the swollen blister‐like tissue you see below: Oak leaf Blister on Laurel Oak leaves. Photo: Peggy Kane, Martin County Master Gardener. Oak leaf blister can also cause leaf distortion and leaf curl. In most cases this is just a cosmetic problem and rarely does any significant damage to an oak. This fungus only attacks the leaves and will not cause harm to the rest of the tree. In some extreme cases a younger tree may experience a large leaf loss. Rake up the fallen infected leaves and dispose of them to avoid spreading the fungal spores. No other treatment is necessary, which frees you up to enjoy the beautiful spring weather! The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information, and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions, or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A&M University Cooperative Extension Program, and Boards of County Commissioners Cooperating..