Identifying and Managing Armillaria Root Rot in Lawns

Symptoms

A white, cauliflower-like fungal mass at the tree base spreading into the lawn suggests Armillaria (honey fungus). It feeds on decaying roots or buried wood.

Causes

• Girdling root cutting off nutrients (look for missing trunk flare on affected side).
• Poor drainage causing root rot.
• Buried construction debris or dead roots.

Management

• Dig out and remove decaying roots/stumps; replace soil.
• Improve drainage.
• Fungicides are largely ineffective; the fungus persists until food source is exhausted (up to 10+ years for large roots).
• Consult an arborist for tree health assessment.

Warning: Never eat unidentified lawn mushrooms.