Green elfcup

Green elfcup (Chlorociboria aeruginosa) is a distinctive fungus from the Ascomycota phylum, known for staining wood a vibrant blue-green color. In the context of forestry and plant health, this fungus acts as a wood-staining agent, colonizing decaying organic matter and affecting the structural and commercial quality of timber.

The pathogen primarily infects hardwood species, including oak, beech, and alder. It typically targets weakened, dead, or rotting wood by spreading its spores through the air, which then infiltrate cracks in the bark. Once established, the mycelium penetrates deep into the xylem, consuming nutrients and depositing pigment throughout the wood tissue.

Symptoms of the infection are unmistakable. The wood becomes stained with a deep, permanent turquoise or blue-green hue due to the accumulation of a pigment called xylindein. During the reproductive stage, the fungus produces small, cup-shaped fruiting bodies, usually 5 to 10 millimeters in diameter, that appear on the surface of the infected wood.

Development and spread of the fungus are highly dependent on environmental conditions. High humidity and moderate temperatures are essential for its proliferation. Shaded areas with poor air circulation and damp soil create an ideal environment for the spores to germinate and colonize new wood material, making it a common sight in moist temperate forests.

The damage caused by green elfcup is primarily economic, as the blue-green staining reduces the aesthetic and technical value of the wood for carpentry and construction. Prevention strategies focus on proper forest management, including the removal of deadwood, improving air circulation in wooded areas, and maintaining dry storage conditions for processed timber to inhibit fungal growth.