Maple Trunk Fungus: Decay Fungus Fruiting Body—Natural Cycle, No Spray Needed

The white growth in the maple’s knot hole is the fruiting body (mushroom) of a wood-decay fungus. The fungus lives in dead heartwood, not living tissue, so it doesn’t kill the tree directly.

Key Points

• Fungus spreads via spores from the conk—removing it reduces spread.
• No chemical can eliminate the fungus inside the trunk.
• Tree remains healthy if canopy is full and green.
• Risk: trunk may weaken and break in high winds over time.

Care

Fertilize with 10-10-10 at 1 lb per inch trunk diameter (fall and spring) to maintain vigor. Simply break off the conk if desired.