Urnula

Urnula is a genus of ascomycete fungi that includes dangerous pathogens contributing to the development of necrosis and the death of weakened woody plants. The most well-known representative, Urnula craterium, is classified as a facultative parasite that often affects previously damaged areas of bark and wood.

The disease is caused by a fungus from the Pezizomycetes class. It typically acts as a saprotroph, but under certain conditions, it exhibits parasitic properties by penetrating through mechanical damage to trunks, frost cracks, or fissures in the bark, classifying this pathological process as infectious wood necrosis.

The primary hosts for Urnula are deciduous tree species, particularly oaks, beeches, and various elm species. The fungus is especially active in colonizing the lower part of the trunk and the root collar, leading to systemic damage and disruption of nutrient transport in cambial tissues.

A key symptom of infection is the appearance of characteristic cup-shaped or urn-shaped black fruit bodies that emerge through the bark or develop on dead branches. As the mycelium spreads, bark necrosis occurs, followed by deep fissures and subsequent wood decay, which significantly reduces the structural integrity of the plant.

To prevent the spread of the infection, it is necessary to carry out sanitary logging and remove infected debris. An important preventive measure is to protect trees from mechanical bark damage, treat wounds with appropriate antiseptics in a timely manner, and maintain an optimal sanitary status of forest stands to prevent the weakening of trees.