Oak Leaf Blister: Cosmetic Fungal Disease

Pin oak in Florida panhandle has raised brown spots (up to 1/2") on leaf undersides, holes where spots were, and ragged edges. Diagnosed as oak leaf blister (Taphrina caerulescens)—a spring fungus favored by frequent rain.

Disease Facts

• Causes leaf depressions (blisters) that turn brown.
• Primarily cosmetic; rarely harms tree health.
• Main effect: premature leaf drop.
• Overwinters on fallen leaves.

Management

1. Rake and destroy all fallen leaves before spring—most effective step.
2. Fungicides (chlorothalonil, mancozeb) only if severe and tree is small enough to spray thoroughly.
3. Improve airflow via pruning.

Reference

UAEX Fact Sheet FSA-7535: Oak Leaf Blister