Fat pholiota

Fat pholiota (Pholiota adiposa) is a parasitic fungus belonging to the Strophariaceae family, known for causing white rot in various hardwood species. As a wood-decay pathogen, it secretes enzymes that decompose lignin and cellulose, significantly reducing the mechanical strength of the affected tree and leading to internal rot.

The host range includes a wide variety of deciduous trees, with a particular impact on orchard crops like apple, pear, and plum trees. It thrives in wounded or weakened trees, using gaps in the bark or unhealed pruning scars as entry points to colonize the xylem. It is also frequently found on dead wood, such as stumps and fallen branches.

Symptoms of an infection are primarily identified by the presence of yellowish to golden, sticky fruit bodies emerging from the bark, usually in clusters. Internally, the disease is manifested by the softening of the wood, which takes on a pale, bleached appearance and becomes soft to the touch. This decay process can compromise the structural integrity of the entire tree trunk.

The fungus develops optimally under conditions of high moisture and moderate temperatures. Spores are primarily dispersed by wind or insects, landing on exposed tissue where they germinate if moisture levels are sufficient. The presence of cracks, frost splits, or poorly managed pruning wounds creates an ideal environment for the rapid establishment of the mycelium.

Effective management focuses on preventive cultural practices rather than direct chemical control. Key strategies include protecting trees from mechanical damage, avoiding improper pruning techniques, and applying protective sealants to all cuts larger than 2 centimeters in diameter. It is essential to remove and dispose of infected logs and fruiting bodies away from the orchard to limit spore dissemination. Regular monitoring and maintaining tree vigor through appropriate fertilization and irrigation are the best defenses against colonization.