Fact Sheet

Bur Oak Blight

Have you noticed black spots on oak leaves?

Are they turning brown, developing notched edges, or hanging on the tree through winter instead of dropping in the fall?

It may be from a condition called bur oak blight. This is caused by a fungus that thrives in cool, wet spring weather and infects the leaves of bur oak trees.

The Problem

Leaves in the lower central canopy are usually infected first because that area stays cool and damp, creating ideal conditions for the fungus to spread—especially in wet, late spring weather.

Symptoms and signs include:

Dark purple to black spots on the veins of leaves
Notch-shaped dead areas at the leaf edges that spread inward
Early leaf drop and canopy dieback

Co-occurring issues or look-alike symptoms:
Oak wilt, two-lined chestnut borer, anthracnose, and armillaria root rot.

The Vineland Prescription

For bur oak blight treatment, apply a root-flare injection of a systemic fungicide in the spring just after full leaf development. Re-treatment should be made in the spring after the next time the infection affects more than 60% of leaves.
Remove infected fallen leaf litter to reduce spore pressure.

The Prognosis

Fungicide treatment will provide good control for several years. Trees should fully recover.

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