What is the risk of applying mulch too close to trunk bases?

• A. Moisture-related issues such as trunk rot and pest habitat.
• B. Increased soil aeration.
• C. Improved trunk drying.
• D. Reduced shade.

Answer: (A)

Piling mulch directly against the trunk creates a damp, warm microenvironment at the base of the tree. That moisture near the bark slows drying after rain or irrigation and encourages fungal decay and disease, which can lead to trunk rot. The damp surface also invites pests and pathogens to take up residence in the mulch near the trunk, compromising tree health and structure. Keeping mulch away from the trunk and applying it in a shallow ring around the base reduces moisture buildup and promotes air circulation, helping the bark stay drier and less susceptible to rot. A good practice is a mulch layer about 2-4 inches thick, with a gap of several inches between the mulch and the trunk, never mound against the trunk.