Lecidella elaeochroma

Lecidella elaeochroma is an epiphytic lichen species commonly found on the bark of various deciduous trees. While it is not a pathogenic organism that directly consumes plant tissues, it is often categorized within agricultural pathology as a biotic factor that indicates poor tree vitality or unfavorable environmental conditions within an orchard.

This species primarily colonizes the bark of fruit trees, such as apples and pears, as well as various forest trees. It utilizes the bark surface as a stable substrate to grow. It is most frequently observed on older, slow-growing, or neglected trees where the bark surface has become stable enough for colonization.

The visual signs of Lecidella elaeochroma include a thin, granular or wart-like thallus that appears greenish-grey to olive-yellow. A key identifying characteristic is the presence of numerous small black apothecia (fruiting bodies) scattered across the lichenized area. These growths give the bark a distinct speckled appearance.

Development is driven by high humidity, moderate temperatures, and lack of direct sunlight within the canopy. The lichen thrives in orchards where sanitation pruning is neglected, leading to poor air circulation and excessive shade. These environments provide the perfect moisture-rich conditions for the spores to germinate and grow.

While the lichen itself does not extract nutrients from the tree, its impact is significant because it blocks bark lenticels, reducing gas exchange. Furthermore, it creates a physical shelter for overwintering pests like scale insects and fungal spores. To manage this, arborists recommend:

• improving air circulation through proper pruning;
• whitewashing trunks with lime;
• manually cleaning infected bark during the dormant season.