Dryad's saddle

Dryad's saddle (Latin: Polyporus squamosus) is a basidiomycete fungus that acts as a significant forest and orchard pathogen. It is recognized as a facultative parasite that initiates white rot, a type of wood decay where the fungus decomposes lignin and cellulose, compromising the structural integrity of the host.

The fungus primarily targets deciduous trees, including fruit species like apple and pear, as well as forest trees such as elm, maple, and walnut. Infection typically occurs through wounds, broken branches, or improperly pruned stubs, allowing the fungal spores to colonize the internal woody tissue of the host plant.

The life cycle involves the production of large, bracket-shaped fruiting bodies that emerge from the host surface. These bodies release masses of wind-borne spores that spread to other vulnerable hosts. Inside the tree, the mycelium spreads rapidly, leading to heartwood decay that can persist for many years, often resulting in the sudden breakage of limbs or the entire tree under stress.

Environmental conditions that favor the spread of Polyporus squamosus include high humidity, poor aeration, and physical trauma to the bark. The fungus thrives when trees are stressed due to drought, poor soil quality, or competition with other plants, making them more susceptible to the colonization of fungal hyphae.

Integrated management is essential for controlling this pathogen. Key strategies include:

• Prompt removal and destruction of fruiting bodies to limit spore dispersal.
• Sanitary pruning to remove dead or infected limbs using sterilized tools.
• Applying wound dressings or sealants to major cuts to prevent spore entry.
• Improving overall tree health to bolster natural defenses against fungal invasion.