Merismodes anomala

Merismodes anomala is a species of basidiomycete fungus that typically colonizes the bark of deciduous trees. In agronomy and arboriculture, it is regarded as a wood-decay fungus that acts as an opportunistic pathogen on weakened or damaged branches, causing structural degradation of the outer wood layers.

This fungus primarily affects a wide range of deciduous hosts, including common forest trees like birch, alder, and hazel, as well as various fruit trees. It is frequently observed on specimens that have already suffered from environmental stress, such as drought, winter injury, or improper pruning practices which create entry points for the fungal mycelium.

The primary symptom of infection is the appearance of tiny, cup-shaped or goblet-shaped fruiting bodies appearing in clusters on the bark surface. These bodies are generally brownish to ochre-colored and feature a velvety or hairy exterior. As the infection progresses, the fungal colonization leads to localized necrosis of the inner bark and cambium, eventually causing branch dieback.

Development and spread of Merismodes anomala are highly dependent on moisture levels. The pathogen thrives in humid environments with poor air circulation, such as densely planted or overgrown orchards. Spores are primarily dispersed via wind and rain splash, allowing them to lodge in bark crevices, frost cracks, or wounds where they germinate and initiate colonization.

Effective management and prevention strategies include several key practices:

• Pruning out and removing infected limbs to reduce the inoculum load.
• Applying wound sealants or protective paints to large pruning cuts.
• Ensuring optimal tree spacing and pruning for proper air movement and light penetration.
• Maintaining tree vigor through appropriate fertilization and water management to improve natural resistance.