Megalariaceae

Megalariaceae is a family of lichenized fungi that are often encountered on the bark of perennial plants and orchard trees. While they are not classified as infectious diseases in the traditional sense, their appearance is frequently a concern for horticulturists and agronomists managing woody species.

These organisms are typically lichenized, meaning they live in a symbiotic association with algae. They function as epiphytes, utilizing the surface of the bark for attachment rather than penetrating the living tissues to extract nutrients. Therefore, they do not act as typical fungal pathogens that cause wilting or necrosis.

The primary symptom is the colonization of the bark with crustose thalli, which can manifest as grey, green, or brown patches. These patches do not cause direct damage to the cambium, but they can cover significant areas of the trunk and branches, especially in older, slow-growing specimens.

Development and spread are strongly correlated with environmental factors such as high humidity, low sunlight exposure, and lack of air movement through the canopy. They thrive in neglected orchards where the density of branches creates a stagnant microclimate that prevents the bark from drying out sufficiently.

Control strategies for these organisms are focused on preventative maintenance of the orchard. Regular pruning to improve air circulation, scraping off dead bark during the dormant season, and applying protective whitewash (often lime-based) are standard procedures that discourage lichen growth and help maintain optimal bark health.

From an agronomic perspective, the presence of Megalariaceae should be treated as an indicator of environmental conditions rather than a direct threat. Keeping the tree vigorous through proper fertilization and irrigation reduces the niche available for these epiphytes, thereby naturally limiting their proliferation on productive orchard trees.