Chlorosplenium chlora

Chlorosplenium chlora is a species of fungi in the family Helotiaceae known for causing distinctive discoloration in the wood of deciduous trees. While primarily acting as a saprotroph, this organism plays a significant role in forest ecology and timber pathology by colonizing weakened plant tissues and decomposing wood structures.

The pathogen responsible is the Chlorosplenium chlora fungus, which belongs to the class Ascomycetes. It predominantly affects hardwood species such as oak, beech, and hornbeam. The fungus secretes pigments and enzymes that degrade lignin, causing a shift in the physical color of the host material to a characteristic greenish or yellowish hue.

Symptoms are most visible on the cross-sections of wood, which show intense green or yellow staining patterns. In addition to the internal coloration, the appearance of small, disc-shaped apothecia on the bark indicates the presence of the mature fungus. As the mycelium colonizes the wood, the tissue gradually loses its structural integrity and mechanical strength.

The development of the disease is highly dependent on humidity and moisture levels. High humidity in the forest environment facilitates the dispersal of spores via wind or water droplets. The pathogen typically enters the tree through wounds, frost cracks, or areas where the bark has been damaged, especially in shaded and poorly ventilated environments.

The economic impact of this fungus is significant in the timber industry, as it degrades wood quality and makes it less suitable for commercial use. Protection strategies focus on:

• minimizing mechanical damage to standing trees;
• conducting timely sanitary pruning;
• maintaining good aeration in timber storage sites;
• preventing water stagnation near forest stands.