Patellaria atrata

Patellaria atrata is a species of fungus in the family Patellariaceae. Often identified as a saprobic organism, it primarily colonizes dead or dying woody tissues. However, in the context of plant pathology, it is recognized for its ability to opportunistically colonize stressed trees, where it can compromise the vitality of the bark and phloem layers.

This fungus typically targets a variety of deciduous tree species. Common hosts include maples, oaks, and ashes, though it can occasionally be found on various fruit-bearing trees. The pathogen thrives on bark that has been previously compromised by environmental stress, insect activity, or mechanical damage.

The primary clinical sign of an infestation is the appearance of small, black, disc-shaped apothecia on the outer bark. These fruiting bodies are often found in clusters. As the fungal mycelium develops underneath the bark, it can cause localized necrosis, leading to bark scaling and potential disruption of nutrient transport within the vascular system of the tree.

The spread of Patellaria atrata is heavily dependent on moisture. High humidity, frequent rainfall, and stagnant air within dense tree stands create an ideal environment for spore dispersal and germination. These conditions allow the fungus to transition from dormant stages to active colonisation of suitable bark surfaces.

Management and prevention focus on maintaining tree vigor through proper silvicultural practices. Reducing canopy density to improve air circulation and sunlight penetration is crucial for managing moisture-related fungal growth. Additionally, standard sanitary measures, such as removing dead wood and treating bark wounds with appropriate fungicides, remain the most effective methods of protection against this pathogen.