Cylindrobasidium evolvens

Cylindrobasidium evolvens is a basidiomycetous fungus typically categorized as a wood-decaying organism. While it often functions as a saprotroph living on dead organic matter, it can also act as a weak parasite on deciduous trees, invading living tissues through wounds or areas of physiological stress, eventually contributing to white rot development in the host.

The host range of this fungus includes various hardwood species such as birch, alder, oak, and beech. In horticultural settings, it is known to affect fruit trees like apple. The infection usually begins in areas where the bark has been compromised, allowing the fungal mycelium to penetrate the cambium layer and subsequently colonize the woody tissue beneath the bark.

Symptoms of an infection include the presence of characteristic fruit bodies on the surface of the bark or exposed wood. These structures appear as thin, resupinate, crust-like formations that are often whitish to cream-colored with a wrinkled or slightly folded surface. Internally, the wood undergoes degradation, losing its structural integrity as the fungus breaks down cellulose and lignin, leading to localized or systemic necrosis.

The development and spread of the fungus are heavily influenced by environmental conditions, particularly high humidity and temperature. Optimal growth typically occurs in damp, shaded environments with poor aeration. Spores are primarily dispersed by wind and water splashes, landing on fresh wounds where they germinate rapidly, especially when temperatures remain within a moderate range of 15 to 25 degrees Celsius.

Damage management focuses primarily on prevention and physical intervention. Cultural practices include proper pruning techniques to avoid leaving large wounds, immediate sealing of cuts with wound paints or fungicides, and the removal of heavily infected tree parts. Maintaining tree vigor through balanced fertilization and irrigation helps the host plant develop better defensive responses against initial colonization.