Phellinus pomaceus

Phellinus pomaceus is a perennial bracket fungus that acts as a significant plant pathogen, primarily causing white heart rot in various stone fruit species. It is a wood-decay fungus that invades the vascular system and structural tissues of trees, leading to the gradual degradation of the wood and the long-term decline of the host plant.

The primary hosts for this fungus include Prunus species such as plums, apricots, cherries, and blackthorns. The fungus is particularly opportunistic, commonly targeting older or damaged trees that have suffered from frost cracks, improper pruning cuts, or physical injuries to the bark, which act as entry points for the fungal spores.

Symptoms are identified by the presence of hard, woody, perennial fruiting bodies (conks) on the trunks or branches of the tree. These structures are typically hoof-shaped or cushion-like, varying in color from grayish-brown to black. Internally, the fungus causes a characteristic white rot, resulting in the softening and structural failure of the wood, which frequently results in branch breakage during storms.

The development and spread of Phellinus pomaceus are heavily dependent on environmental humidity and tree wound accessibility. Spores are dispersed through wind and rain splash, landing on exposed xylem where they germinate. Once established, the mycelium penetrates deeper into the heartwood, secreting enzymes that break down lignin and cellulose, slowly compromising the tree's internal integrity.

• Practice strict sanitation by disinfecting pruning tools between cuts on different trees.
• Seal all major pruning cuts and physical injuries with antifungal tree wound paint.
• Remove and destroy all visible fungal conks to reduce the local spore load in the orchard.
• Maintain tree vigor through proper fertilization and irrigation to improve natural defense.
• Apply white latex paint or whitewash to trunks to prevent sunscald and frost damage.