Cerrena unicolor

Pathogen and disease type: Cerrena unicolor is a basidiomycete fungus known to cause white rot in various hardwood trees. It acts as a wood-decay pathogen, breaking down lignin and cellulose within the host's woody tissue. The disease is typically characterized by the development of stem cankers and structural decay, significantly compromising the tree's internal integrity.

Affected crops: This fungus is a broad-spectrum polyphage, impacting numerous deciduous species. Common hosts include birch, poplar, beech, maple, and ash. It is particularly noted for causing significant damage to the Sweet Gum (Liquidambar styraciflua), where the pathogen infiltrates the stem, leading to severe localized necrosis and structural weakness.

Symptoms and signs: The most visible sign of infection is the presence of the fungus's fruiting bodies on the trunk or branches. These are typically greyish or whitish with a hairy/tomentose surface. Internally, the wood exhibits advanced white rot, often accompanied by deep fissures, bark cracking, and distinct canker formations where the pathogen has successfully invaded the cambium layers.

Development and spread: The fungus thrives in environments with high humidity and moderate temperatures. Spores are primarily dispersed via wind or insect vectors, infiltrating trees through mechanical wounds, frost cracks, sunburn lesions, or pruning cuts. Trees that are already stressed by drought, poor soil conditions, or other pathogens are significantly more susceptible to infection.

Harmfulness and protection: The primary economic impact is the degradation of timber quality and increased risk of tree failure during storms.

• Removal and destruction of heavily infected wood to reduce spore load.
• Proper wound management using protective dressings or antifungal treatments.
• Maintaining tree vigor through appropriate fertilization and site management.
• Regular inspections to detect early symptoms of infection in high-value ornamental or forest trees.