Bulgaria inquinans

Bulgaria inquinans is an ascomycete fungus often referred to as the black bulgar or the leather rot fungus. While it is primarily a saprotrophic organism that plays a role in wood decomposition, it can also act as a weak pathogen on stressed or damaged trees, making it a point of concern for arboriculture and forestry management.

The fungus typically colonizes deciduous trees, showing a strong preference for oak, beech, and hornbeam species. It targets branches and stems that have been compromised by environmental stress, structural damage, or previous infections, using these entry points to establish its mycelium within the wood tissue.

The primary diagnostic sign of this fungus is the appearance of fruit bodies, which are gelatinous, cup-shaped, and black or dark brown in color. When these fruit bodies mature, they release dark-colored spores mixed with a liquid substance, creating distinctive black streaks and stains on the bark, which serves as a visual indicator of its presence.

Fungal development is highly dependent on environmental conditions, particularly high humidity and temperatures during the spring and autumn seasons. Spores are disseminated by wind and water splash, quickly infecting fresh wounds on susceptible hosts, especially in dense or unmanaged tree stands where air circulation is restricted.

Management of the disease centers on cultural practices aimed at reducing the presence of decaying wood. Proactive measures include pruning affected branches, sealing bark wounds with appropriate treatments, and maintaining tree vigor through correct fertilization and watering. By ensuring good site hygiene and removing dead wood, growers can significantly lower the risk of infection.