Rosellinia aquila

Rosellinia aquila is a member of the Xylariaceae family, recognized as a significant fungal species involved in the decomposition of woody substrates. While it functions primarily as a saprotroph in natural ecosystems, under favorable conditions, it can colonize stressed or weakened trees, turning from a decomposer into a potential threat to tree vigor and structural integrity.

The host range of this fungus is primarily comprised of various broad-leaved trees, including beech, oak, and hazel. It typically exploits trees that have been compromised by environmental stress, such as drought, frost cracks, or mechanical injuries. By infiltrating the xylem through bark wounds, the mycelium gradually invades the inner wood, utilizing cellulose and lignin as its primary energy sources.

Clinical signs of an infestation include the appearance of dense, black, carbonaceous fruiting bodies known as perithecia on the surface of the bark. These structures, which look like tiny clusters of coal, are a telltale sign of the fungus's reproductive phase. Internally, the wood undergoes a transformation characterized by white rot, leading to a loss of structural support and eventually causing the tree to become brittle and prone to breakage.

The development of Rosellinia aquila is highly correlated with microclimates that maintain high humidity and consistent moisture. Areas with poor air circulation or soil saturation are particularly susceptible to the accumulation of fungal spores. The spread occurs through airborne ascospores and via mycelial transfer, which happens when tree roots or branches come into physical contact with existing infected wood or decaying organic matter in the soil.

Control and prevention strategies are centered on forest and garden hygiene.

• Remove dead wood and stumps that serve as primary reservoirs.
• Protect trees from mechanical injuries during maintenance.
• Apply copper-based fungicides to pruning wounds.
• Improve overall tree health through proper fertilization and thinning to ensure adequate air circulation.