Collemataceae lichens
Collemataceae
Collemataceae lichens appear as gelatinous, soft, or brittle growths on tree bark. When dry, they look like dark brown or black scales, but when wet, they absorb moisture, becoming jelly-like and expanding significantly in size on the host surface.
What the section contains
Collemataceae lichens
They typically colonize older trees with rough or deteriorating bark. Unlike true parasitic fungi, they do not penetrate the wood tissues, but they form a thick layer that can alter the tree's microenvironment and retain moisture on the bark surface for long periods.
It is important to note that Collemataceae lichens are not a plant disease in the traditional sense, as they are not pathogens that feed on the tree. They are complex symbiotic organisms made of fungi and cyanobacteria (often of the genus Nostoc).
The tree serves only as a physical substrate for these organisms. In an agricultural context, their presence is considered an indicator of poor tree vigor, slow growth, or a lack of proper airflow within the canopy rather than a primary biological infection.
The development of these lichens depends on high air humidity and adequate light exposure. They thrive in unmanaged, dense orchards where the lack of proper pruning prevents the bark from drying out quickly after rainfall.
The age of the tree is a significant factor: old or neglected bark provides a perfect anchor for spores. They prefer microclimates that remain consistently humid, favoring areas with high rainfall or heavy dew patterns that allow them to hydrate and grow.
While they do not derive nutrients from the tree, Collemataceae lichens can harbor various pests. Their porous and protected structure provides excellent overwintering sites for harmful insects, mite larvae, and the spores of true pathogenic fungi.
Excessive coverage on branches can slightly inhibit the bark's gas exchange. Furthermore, a heavy presence of these lichens usually indicates a stressed or aging tree that is not growing rapidly enough to shed its outer bark, requiring attention.
The most effective strategy involves regular orchard maintenance, including pruning to improve air circulation within the tree crown. Cleaning the trunk of dead bark and debris is a highly effective way to reduce the colonization surface.
- Mechanical removal using specialized scrapers or stiff brushes.
- Applying lime wash to trunks to create an unfavorable surface.
- Treating affected areas with a 1–3% copper sulfate solution.
- Improving overall tree health through balanced fertilization and care.