Inonotus cuticularis

Inonotus cuticularis is a parasitic fungus belonging to the Hymenochaetaceae family, primarily recognized as a causal agent of white heart rot in various hardwood tree species. This pathogen degrades the internal structure of the wood, leading to substantial decay and the loss of mechanical strength in infected trees.

The host range is extensive, commonly including oak, beech, elm, chestnut, and maple. The fungus typically gains entry into the woody tissue through wounds, pruning cuts, or bark lesions, allowing the mycelium to colonize the heartwood over time. It is especially opportunistic when trees are already under environmental stress.

The primary diagnostic sign is the presence of annual fruiting bodies. These sporocarps are often arranged in tiers, characterized by a brownish, leathery, and velvety surface. Internally, the disease is manifested by white, spongy decay, while externally, it often correlates with crown thinning, foliage yellowing, and branch dieback.

• Warm and humid seasonal conditions favoring fungal growth
• Presence of unprotected mechanical wounds on the trunk
• Old or declining trees with reduced resistance
• Poor air circulation in dense forest or orchard stands

The severity of this disease is linked to its ability to compromise the structural integrity of the tree, which can result in hazardous structural failure or the eventual death of the specimen. In urban and landscaped environments, this poses a significant risk to public safety and surrounding infrastructure.

Control strategies emphasize preventative care, such as minimizing bark and wood injuries. Proper pruning techniques and the immediate sealing of fresh wounds are essential. If fruiting bodies are observed, the extent of the decay should be assessed, and in cases of advanced infection, the removal of the tree is often necessary to stop the spread of inoculum to healthy trees.