Oak Apple Galls on Red Oak: Harmless Curiosities

A North Texas red oak has rounded, walnut-shell-like growths on leaves and stems—green when small, cream-colored and ping-pong ball sized when large. Inside: fibrous mass resembling dandelion seed head.

Diagnosis: Oak Apple Gall

Caused by a cynipid wasp. Galls form on leaf midribs or stems in spring. Each contains a single larva in a hard capsule. Green galls turn brown and papery.

Impact

• Cosmetic; minimal health effect.
• Heavy infestations may cause early leaf drop.
• Natural enemies usually control populations.

Management

No treatment needed. On small ornamental trees, galls can be picked or pruned off. Otherwise, ignore them.

Reference: Wikipedia Oak Apple Gall