Oak Galls (Horned/Gouty): Cosmetic, Not Lethal

Lumpy Growths on Oak: Horned or Gouty Oak Gall

Sticky green → hard brown balls on twigs = horned oak gall (Callirhytis cornigera) or gouty oak gall (C. quercuspunctata). Caused by tiny cynipid wasps.

Key Facts

• Galls are plant tissue induced by wasp chemicals.
• Leaf galls: harmless. Twig galls: can weaken branches if heavy.
• Two+ year life cycle. Wasps overwinter away from tree.
• Once formed, galls don't drain tree resources.

Management

• No sprays—wasps protected inside galls; timing impossible.
• Prune lightly infested twigs when galls are small.
• Rake/destroy fallen infested leaves.
• Natural enemies usually prevent repeat outbreaks.

Bottom Line

Galls look alarming but rarely threaten tree health. No chemical control needed.