Lecanorales

The order Lecanorales consists of various lichen species that are frequently misidentified as agricultural plant pathogens. It is critical for agronomists to distinguish between true plant diseases and these symbiotic organisms. Lecanorales are not parasites; they do not infect plant tissues or consume nutrients from the host plant, and therefore do not cause plant death or decay.

These lichens utilize the bark of trees as a stable substrate for growth. While they are not harmful to the plant's health directly, their presence is often an indicator of environmental conditions. A heavy buildup of lichens on tree trunks is typically observed on older, slow-growing, or neglected trees that provide a stable, long-lasting surface for colonization.

Symptoms of their presence include the appearance of crust-like, scale-like, or shrubby structures on the surface of branches and trunks. These structures often display various shades of grey, green, or yellow. Unlike pathogenic fungi, these growth forms do not cause lesions, wilting, or necrosis, as they exist purely on the outer surface of the bark.

The development of Lecanorales is favored by high atmospheric humidity, lack of air circulation, and insufficient sunlight reaching the bark. They thrive in environments where the host plant's growth has slowed, often in orchards that lack routine maintenance. Proper orchard management, including consistent pruning, effectively limits their ability to establish colonies.

Effective management focuses on physical control rather than heavy chemical usage. Regular sanitation, including the removal of dead bark and cleaning the trunk with appropriate tools, is the most recommended practice. Following this with a white lime wash helps maintain tree hygiene, removes potential shelters for overwintering pests, and discourages further lichen attachment.