Datronia mollis

Datronia mollis is a species of bracket fungus in the Polyporaceae family, commonly recognized as a wood-decay pathogen. It primarily thrives on dead or decaying wood, but it can also colonize living trees that have been weakened by environmental stressors, mechanical damage, or secondary infections from pests.

This fungus predominantly affects a wide range of deciduous trees, including birch, alder, oak, beech, and willow. The pathogen is opportunistic, meaning it easily takes hold in areas where the tree's natural defense mechanisms are compromised, such as pruning wounds, broken branches, or frost cracks in the bark.

The primary symptom of infection is the emergence of leathery, resupinate to effused-reflexed fruit bodies on the wood surface. These brackets are often dark brown to blackish with a velvety texture. Once the mycelium invades the inner wood, it initiates the process of white rot, breaking down structural components like lignin and cellulose, which turns the wood into a soft, fibrous, and whitish mass.

Environmental conditions play a critical role in the growth and dispersal of Datronia mollis. The fungus flourishes in humid, shaded environments where moisture levels remain consistently high. Spores are primarily disseminated by wind and splashing rainwater, facilitating the spread of the pathogen across various hosts in the immediate vicinity during periods of high humidity.

The impact of this disease is characterized by the degradation of wood integrity, which significantly reduces the structural stability of the tree and makes it prone to wind-throw. Prevention and control strategies focus on rigorous orchard and forest sanitation, including:

• Regular inspection for signs of decay or fungal bodies.
• Proper pruning techniques to facilitate quick callus formation.
• Sealing large wounds with appropriate protective agents.
• Removing and destroying heavily infected wood to prevent spore release.