Hericium coralloides

Hericium coralloides, commonly known as the coral tooth fungus, is a xylotrophic fungus that can act as a pathogen in woody plants. While it is primarily found in forests, its presence on fruit trees indicates a significant risk of wood rot, affecting the structural integrity and longevity of the host plant.

The causative agent is the fungus itself, which acts by secreting enzymes that decompose lignin and cellulose within the host's wood. This process results in white rot, a specific type of fungal decay that significantly weakens the woody tissue. The disease is progressive and often irreversible once it reaches the inner heartwood.

The fungus typically affects broad-leaved trees, including common orchard species like apple and pear trees. It targets trees that are already stressed or damaged. Entry points for the fungal spores include pruning wounds, frost cracks, broken limbs, and any exposed tissue where the bark has been compromised.

Symptoms are identified by the growth of unique, coral-like, white to creamy fruiting bodies emerging from the tree bark. Internally, the wood becomes bleached, spongy, and brittle. As the decay spreads, the tree loses its ability to transport nutrients, leading to branch dieback, crown thinning, and an increased risk of structural failure during adverse weather conditions.

Development is favored by high humidity and the presence of unprotected woody wounds. Preventing the spread of Hericium coralloides involves rigorous orchard maintenance practices:

• Practicing clean pruning techniques and disinfecting tools between trees.
• Sealing all cuts and wounds with appropriate wound dressings or fungicidal agents.
• Promptly removing and burning severely infected wood to minimize spore dispersal.
• Ensuring proper plant nutrition to boost the tree's natural defense mechanisms against rot.