Daldinia

Daldinia is a genus of fungi within the Xylariaceae family, known primarily for its role in decaying wood. The most common species, Daldinia concentrica, is often referred to as "King Alfred's cake" due to its dark, spherical fruiting bodies. While it acts mostly as a saprophyte on deadwood, it can colonize living trees that are stressed, injured, or weakened by environmental factors.

The fungus functions as a wood-decay pathogen. It spreads primarily through spores released from its fruiting bodies. These spores infiltrate the tree through wounds, such as broken branches, frost cracks, or improper pruning cuts. Once inside, the mycelium begins to degrade the cellulose and lignin, the structural components of the tree's vascular system.

Daldinia mainly affects deciduous trees, including ash, birch, beech, and occasionally orchard trees. Trees that are already weakened by lack of maintenance, severe competition for nutrients, or unfavorable climatic conditions are most susceptible. Once the fungus establishes itself, it creates internal rot, which weakens the tree's structural integrity over several years.

The primary symptom is the emergence of hard, dark, semi-spherical fruiting bodies on the bark of the trunk or branches. These growths are firm, charcoal-like in appearance, and develop a distinct concentric layering when sliced. Their presence is a clear indicator that the tree is suffering from significant decay and requires immediate horticultural attention.

Protecting your trees from Daldinia focuses on prevention. Proper arboricultural practices are essential: ensure trees are not overly crowded, provide adequate fertilization to maintain vigor, and always treat pruning wounds with appropriate sealants. Removing dead or decaying wood from the vicinity is also crucial to reduce the overall spore load in the environment and prevent new infections.