Trichotheliales

Trichotheliales is an order of fungi within the class Dothideomycetes. These organisms are primarily known for their lichenized lifestyle, where they form complex symbiotic associations with algae. While not classified as primary agricultural pathogens, they are frequently observed on the bark and leaves of trees in humid, tropical, and subtropical climates, often appearing as crust-like growths.

The biological nature of Trichotheliales involves the production of ascomata, specifically perithecia, which are typically flask-shaped and partially embedded in the host substrate. Because they are often lichenized, they derive nutrients through the photosynthetic activity of their algal partners rather than by parasitizing the living tissues of the host plant, making them more of a botanical curiosity than a direct threat to crop health.

The target hosts include various tree species, particularly those in orchard systems with high canopy density. Common crops affected by the presence of these fungal colonies include coffee, citrus, and other perennial crops grown in warm, humid regions. Their distribution is strictly limited by microclimate, preferring areas with high relative humidity and low light penetration.

Symptoms of their presence include the appearance of small, hard spots, dots, or patches on the bark, which can sometimes be confused with fungal leaf spot diseases or bark infections. Unlike true pathogens, they do not produce symptoms such as soft rot, wilting, or necrotic lesions on the plant tissue. They essentially exist as part of the epiphytic community living on the surface of the plant.

Control measures are rarely necessary, as these fungi do not cause significant crop losses. However, if the coverage becomes excessive, it may indicate poor tree management, such as inadequate pruning or high humidity. Integrated management techniques include:

• Pruning to increase airflow and light penetration within the canopy.
• Sanitation to remove dead branches.
• Maintaining optimal tree spacing to reduce humidity.
• Monitoring to ensure they do not harbor other pests or pathogens.