Oak Twig Galls: Identification and Management

Gall Types

Large woody knots on oak branches are likely gouty oak gall or horned oak gall, caused by cynipid wasps. They can girdle branches and cause dieback.

Management

• Prune and destroy galled twigs when small.
• Rake and destroy fallen leaves.
• Maintain tree health with fertilization (10-10-10 at 1 lb/inch trunk diameter).
• Insecticides are impractical due to timing difficulties.

Natural enemies usually keep populations in check; severe infestations are cyclical.