Mushrooms on Mimosa Trunk: Decay Fungus, Not a Killer

Fungal Conks on Mimosa Indicate Heart Rot

The white-to-black mushroom shelves (1–6 inches) on your 20-year-old mimosa’s trunk and roots are decay fungi fruiting bodies. They digest dead heartwood, not living tissue, so they won’t directly kill the tree. But they hollow the trunk over decades, increasing structural failure risk.

Management

• Remove loose bark around conks to help wound closure.
• Watch for borers (sawdust, holes)—spray trunk with Merit or Onyx if seen, or preventively.
• Fertilize for vigor: 10-10-10 at 1 lb per inch trunk diameter, scattered and watered in. Repeat in fall after leaf drop.

Decay can’t be cured, but a vigorous tree compartmentalizes better. Monitor lean and cavity size; consult an arborist if concerned about stability.