Decay Fungus on Hackberry: Manage, Don’t Cure

Fungal Conks on Hackberry Indicate Internal Decay

The large fungal growths on your hackberry’s trunks are decay fungi (wood-rotting basidiomycetes). They digest dead heartwood, not living tissue, so they won’t kill the tree directly. However, they hollow the trunk over time, increasing failure risk. One of three main trunks is already dead.

Action Plan

• Remove loose bark around conks to aid wound closure.
• Watch for borers: Sawdust or holes mean borers—spray wound area with Merit or Onyx 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 improved health slows progression. Monitor structure; consult an arborist if the tree leans or cracks worsen.