Phellinus gilvus

Phellinus gilvus is a destructive wood-decay fungus belonging to the Hymenochaetaceae family. This pathogen is known as a white-rot agent, which selectively degrades lignin and cellulose, leading to the structural weakening of hardwood trees. It typically acts as a wound parasite, infecting trees through damaged bark or pruning cuts.

The host range of Phellinus gilvus is extensive, affecting numerous broadleaf species, including common orchard fruit trees like apples, pears, and plums, as well as forest hardwoods like oaks and beeches. The fungus is particularly opportunistic, colonizing trees that are already stressed or have been injured by environmental factors or poor maintenance.

Visible symptoms include the development of perennial, shelf-like fruiting bodies (conks) on the tree trunk or major branches. These sporocarps usually exhibit a rusty-brown to yellowish-tan surface with a porous underside. Internal colonization leads to the degradation of the heartwood and sapwood, turning the timber soft, brittle, and fibrous, which significantly increases the risk of tree failure during storms.

Environmental conditions that favor the spread of this fungus include high humidity and moderate temperatures. The spores are primarily wind-dispersed and land on exposed wood surfaces. Once established, the mycelium penetrates deep into the vascular system, spreading through the xylem and parenchyma cells, progressively depriving the tree of its ability to transport nutrients and water.

Effective disease management relies on preventative cultural practices. Key strategies include sanitizing pruning tools to prevent cross-contamination, promptly removing and destroying heavily infected wood, and painting large pruning wounds with protective fungicides or pruning sealants. Maintaining overall tree vigor through adequate fertilization and irrigation is essential to help trees compartmentalize wounds and resist infection.