Hypsizygus tesselatus

Hypsizygus tesselatus, commonly known as the beech mushroom, is a basidiomycete fungus that functions primarily as a wood-decay agent. While it is cultivated commercially for consumption, in natural and managed landscapes, it is recognized as a cause of white rot, impacting the longevity of hardwood trees.

The disease is initiated by fungal mycelium colonizing trees through mechanical wounds, frost cracks, or improper pruning cuts. As a white rot pathogen, it specializes in degrading lignin, which results in the wood losing its structural integrity and becoming fibrous and bleached in appearance.

Hardwood species such as beech, elm, maple, and poplar are the most susceptible hosts. The fungus often establishes itself in the heartwood, slowly expanding outward and significantly weakening the tree's stability, which poses a risk of breakage during severe weather conditions.

Clinical signs include the development of clusters of fruiting bodies on the trunk or branches and a distinct, localized softening of the wood. The interior of the tree often exhibits a complex mottled pattern, representing the active zones of wood decomposition carried out by the fungal enzymes.

Protection strategies focus on tree vitality and physical barrier maintenance. Pruning should be performed using sterile tools during dormant periods to minimize exposure. Application of wound dressings and the removal of severely infected wood are critical to preventing the spread of spores to neighboring susceptible trees.