Melaspilea

Melaspilea is a genus of lichenicolous fungi that exhibit parasitic or saprotrophic life cycles, residing primarily on the thalli of lichens found on the bark of various trees. While lichens themselves are not parasites of trees, the dense colonization of these fungi can signify an imbalance in the tree's health or an environment with excessive moisture, leading to the gradual degradation of the tree's surface layers.

The causal agents belong to the class Ascomycetes. In an agronomic context, they are often observed on older fruit trees, ornamental species, and forestry specimens. These fungi thrive on the micro-ecosystem provided by lichens, and under high density, they can create conditions that hinder the bark’s ability to breathe and manage moisture, effectively turning a passive lichen layer into a source of stress for the host tree.

Symptoms of infestation are identified by the presence of small, dark, often submerged apothecia (fruiting bodies) that appear as black spots or streaks across the surface of the lichen. In severe cases, the lichen thallus may turn black or brown and disintegrate. This degradation can lead to secondary cracks in the bark, potentially providing entry points for other opportunistic pathogens or wood-boring insects.

Environmental conditions that favor the development and spread of Melaspilea include consistently high humidity, lack of sunlight in the canopy, and stagnant air. The spores are typically wind-dispersed or spread through water runoff along the bark during rain events. Rapid proliferation occurs when these environmental stressors are combined with an accumulation of old, undisturbed lichen growth.

Protection and preventive measures focus on improving tree hygiene. Pruning to enhance airflow and light penetration is essential for discouraging lichen growth. Additionally, cleaning trunks with stiff brushes during the dormant season helps remove the substrate for the fungus. Applying horticultural lime washes or copper-based treatments to the trunks can effectively modify the pH of the bark, preventing the re-establishment of lichen-fungal complexes.