Cerrena

Cerrena is a genus of wood-decay fungi belonging to the Polyporaceae family. The most prominent species, Cerrena unicolor, functions as a parasitic organism that predominantly affects weakened deciduous trees, causing significant structural damage to wood tissues.

The disease is caused by the spread of fungal mycelium, which invades the tree through open wounds, pruning cuts, or frost cracks. Once established, the fungus begins a process of white rot, effectively decomposing lignin and cellulose, which are the main structural components of the tree's internal wood.

Common hosts for this fungus include a wide variety of hardwoods such as birch, beech, maple, and aspen. While it plays a natural ecological role in breaking down dead organic matter in forests, it becomes a serious pathogen when it infects landscape trees, orchards, or managed forest stands that have been stressed by drought or insects.

Visible symptoms include the emergence of shelf-like, hairy, brownish-gray fruiting bodies on the trunk or branches. Internally, the wood becomes discolored, light in weight, and prone to splintering. The structural integrity of the tree is often severely compromised, leading to increased hazards from falling limbs or tree failure.

Effective management requires a focus on sanitation and preventive care. This includes the prompt removal of infected wood, the application of protective sealants to pruning wounds, and the implementation of cultural practices that minimize tree stress, such as proper watering and nutrient management, to help trees defend themselves against fungal colonization.