Bisporella

Bisporella is a genus of fungi belonging to the Helotiaceae family. While primarily categorized as saprotrophs that decompose dead organic matter, these fungi can opportunistically colonize weakened living tissues of woody plants, acting as an infection agent that accelerates the degradation of plant cell walls.

The causative agent involves ascomycete fungi that propagate via spores. The disease is characterized by localized necrosis and structural rot. The pathogen typically enters through mechanical injuries, such as broken branches, pruning cuts, or frost cracks, where the wood is exposed and vulnerable to colonization.

This fungus primarily affects deciduous trees, including oak, beech, and birch, as well as various fruit trees in orchards. Host plants that are stressed due to improper irrigation, nutrient deficiencies, or previous pest damage provide an ideal environment for the fungus to establish its mycelium network.

Symptoms include the emergence of tiny, bright yellow or lemon-colored disc-shaped fruiting bodies directly on the bark. Surrounding areas of the wood often turn dark, become spongy, and lose structural integrity. Favorable conditions for development include high humidity, stagnant air, and moderate temperatures.

Effective protection and prevention rely on good horticultural practices. This includes regular pruning of deadwood to eliminate the fungus's food source, prompt treatment of mechanical wounds with protective grafting wax, and ensuring proper tree hygiene to prevent secondary infections. Maintaining strong tree immunity through balanced fertilization is key.