Maple Tree Oozing White Foam: Bacterial Wetwood (Slime Flux)

Foamy White Sap from Maple Bark Cracks? It's Wetwood

A 20-year-old Crimson King maple with vertical bark cracks pushing out sweet-smelling white foam has bacterial wetwood (slime flux). Anaerobic bacteria in heartwood produce gas pressure, forcing fermented sap out. Bugs love it; the tree tolerates it.

Key Points

• Not a decay fungus; infected wood resists rot.
• Triggered by stress: heat, drought, wounds.
• No cure; flux stops on its own.
• Do not drill drains or apply wound dressings.

Management

• Remove loose bark in flux area; let dry.
• Flush with 10% bleach (1:9) to reduce odor/insects.
• Maintain tree vigor: water in drought, mulch, avoid wounds.

The tree is not in imminent danger. Wetwood is a chronic condition, not a death sentence.