Lachnellula flavovirens

Lachnellula flavovirens is an ascomycete fungus known to colonize the bark of various coniferous species. It acts as a facultative parasite, often affecting stressed or weakened trees, particularly those in the genus Larix. The fungus disrupts the integrity of the vascular system, causing bark lesions and potentially leading to the death of the affected tissues or branches.

The primary hosts for this pathogen include larch and certain species of pine. It is frequently encountered in forest nurseries and young plantations where high density and moisture retention create optimal microclimatic conditions for fungal development. The disease can be particularly damaging to young saplings, often causing girdling of the stems which results in rapid decline.

Symptomatology is dominated by the emergence of characteristic apothecia. These fruiting bodies are typically yellow to greenish-yellow in color and appear in clusters along the bark or within cankerous depressions. The underlying bark becomes necrotic, often exhibiting cracking, while the wood beneath may show signs of discoloration as the mycelium penetrates deeper into the host's structure.

The spread of the fungus is highly dependent on environmental factors, particularly moisture and temperature. Spore production and dissemination occur via wind and rain splash, targeting bark fissures or wounds. Stagnant air and high humidity in dense plantations facilitate the establishment of the fungus, making dense stands significantly more susceptible to outbreaks compared to well-managed, open forests.

Management and prevention focus on enhancing stand hygiene and reducing pathogen pressure. Silvicultural practices such as thinning are essential to improve air circulation and reduce moisture on bark surfaces. Infected branches or severely damaged trees should be removed and destroyed to minimize the local inoculum load. In nursery settings, ensuring proper spacing and regulating humidity can effectively suppress the disease cycle.

• Regular thinning of forest stands
• Sanitary pruning of infected limbs
• Proper nursery sanitation practices
• Monitoring of tree health during wet seasons