Inonotus nodulosus

Inonotus nodulosus is a wood-decaying fungus belonging to the Hymenochaetaceae family, commonly recognized as a causal agent of white heart rot in broad-leaved trees. It typically acts as a wound parasite, invading the host through mechanical damage or weakened areas of the wood tissue.

The primary hosts of this fungus include various deciduous species such as beech, hornbeam, birch, oak, and linden. It can also affect fruit trees if they are left untreated after pruning, making proper orchard management essential for preventing the establishment of the pathogen.

Visible symptoms are characterized by the emergence of small, cushion-shaped or nodular fruit bodies on the bark of trunks and branches. These fungal structures are often dark brown and woody. Internally, the fungus causes progressive degradation of lignin and cellulose, leading to a bleached, fibrous rot within the heartwood of the tree.

Environmental conditions that favor the spread of Inonotus nodulosus include high humidity and moderate temperatures ranging from 15°C to 25°C. Spores are primarily disseminated by wind and rainwater, seeking entry points such as broken branches, frost cracks, or improper pruning wounds where they can germinate and establish mycelial mats.

The impact of this disease is significant, as it weakens the structural integrity of the tree, often resulting in branch dieback or total collapse due to storm damage. Effective control requires rigorous sanitation practices, including the removal of dead wood and infected branches, the use of specialized wound dressings after pruning, and avoiding unnecessary trauma to tree trunks.