Understanding Decay Fungus Fruiting Bodies on Oak Trees

A white, slimy, condensation-dripping growth appeared at the base of an oak tree.

Identification

This is the fruiting body (conk/mushroom) of a decay fungus living on dead woody cells inside the trunk. The fungus entered through a bark wound years ago. It does not harm living cambium cells under the bark. Decay progresses slowly over many years, potentially hollowing the tree, but healthy trees coexist with internal decay indefinitely.

Management

No treatment removes internal decay. Fertilize every other year with 10-10-10 at 1 lb per inch trunk diameter, applied before rain. The fruiting body will dry naturally or can be removed—neither affects the fungus inside. Monitor tree structure; if large limbs begin breaking with hollow centers, consult an arborist for hazard assessment.