Oak Leaf Galls: Cosmetic, No Treatment Needed

Your oak has orange/red globular spots on leaves and knotty root growths in lawn. Leaf spots = gall wasps; root knots = crown gall.

Leaf Galls (Gall Wasps)

• Wasp lays egg → chemical induces leaf tumor (gall).
• Larva develops inside; emerges late summer.
• Cosmetic only; photosynthesis near normal.
• No spray needed. Natural enemies control wasps.

Root Galls (Crown Gall - Agrobacterium)

• Bacteria enter wounds → transform cells into tumors.
• Woody, irregular galls at/below soil line.
• Can girdle trunk if severe; weakens tree.
• No cure. Prevention: avoid wounding roots/trunk.

Management

• Fertilize fall & spring: 10-10-10 at 1 lb/inch diameter.
• Water during drought.
• Mulch to protect roots from mowers.
• Accept leaf galls; monitor crown gall.

Bottom Line

Leaf galls harmless. Crown gall serious but untreatable. Maximize tree health to compensate.