Tephromela

Tephromela is a genus of crustose lichens that often colonizes the bark of trees. While not a parasitic disease in the traditional sense, its presence is frequently considered an indicator of tree vitality levels. Agronomists monitor these lichens because they can occupy space that otherwise would allow for healthy bark expansion and gas exchange.

From a biological perspective, Tephromela consists of a fungal partner and an algal symbiont. In agricultural settings, species such as Tephromela atra attach themselves to tree trunks and branches. They thrive in environments with clean air, but their rapid proliferation on cultivated trees is often linked to the slow growth or structural damage of the bark surface.

The host range includes a variety of fruit trees and ornamental species. The lichen is particularly noticeable on older trees with rougher, slower-growing bark. While the lichen itself does not consume plant nutrients, it alters the micro-environment of the bark surface, potentially shielding harmful pests from pesticides and natural predators.

Symptoms of heavy colonization include the appearance of grey, crusty patches with distinctive small black apothecia. Although the plant is not actively killed by the lichen, the accumulation of organic matter under the crust can lead to increased moisture retention, which sometimes encourages secondary fungal infections or bark rot in susceptible varieties.

Management strategies focus on orchard hygiene and vitality. Manual removal of lichens using soft brushes is effective for young trees, while chemical control involves using lime wash or diluted copper-based fungicides to inhibit growth. Proactive care, including optimal fertilization and pruning to ensure sufficient sunlight, is the best prevention against excessive lichen colonization.

• Manual scrubbing of lichen-covered bark.
• Application of lime wash for bark sterilization.
• Copper-based spray applications during dormancy.
• Optimizing tree canopy density for airflow.
• Regular bark health inspections.