Oak anthracnose is a fungal disease which infects the leaves of white oaks. The infections initially appears as dead spots along the leaf’s veins, and spreads outward toward the edge of the leaf, causing the leaf to curl and deform.
The fungus overwinters in fallen leaves and in cankers on the twigs. Wind and rain carry fungal spores to young leaves. The fungus then enters the new host leaves. Dead spots develop where the fungus enters. The dead spots will continue to grow, causing the leaf to pucker and curl. During rainy season, the fungus can cause defoliation. The fungus can also enter twigs, causing cankers and twig dieback.
Once the fungus is established in the growing season, chemical treatment may have minimal effect. Professional pruning will be most beneficial. Infected twigs should be removed below the canker. Fallen leaves should be collected, and all tree waste disposed – by burning, if possible.
The following spring, just after bud break, the infected trees should be sprayed with fungicide available to professional arborists and licensed pesticide applicators.