Monoblastiaceae

The primary fungal agents in this group include species of the genus Monoblastia. These fungi form symbiotic relationships with algae, resulting in crustose or squamulose thalli that adhere tightly to the substrate.

Biologically, these fungi belong to the order Trypetheliales. They feature perithecial ascomata, which are immersed in the plant bark or the fungal thallus, providing protection for the reproductive organs.

The disease type is nominal. Unlike parasitic pathogens, Monoblastiaceae do not penetrate deep into living plant tissues but utilize the bark strictly as a physical substrate for attachment.

The life cycle of the fungus is closely linked to bark moisture, where spores germinate to form hyphae, gradually expanding into a thallus that can persist on a tree for many years.

External signs of these fungi appear as small, often barely visible spots or coatings on the smooth bark of young trees and shrubs.

The thalli appear as crusts, which may vary in color from light gray to olive or brownish shades. They often coalesce, covering significant portions of the trunk.

Upon close inspection, one can observe tiny black dots—these are the ostioles of the fruiting bodies immersed in the thallus tissue. These structures are a characteristic sign of the family.

Unlike other bark diseases, the surface does not crack or exude sap when Monoblastiaceae are present. Bark coloration may change slightly due to the fungi's pigments.

Symptoms are most noticeable during wet periods when the thallus swells and becomes more distinct compared to the dry surface of healthy tree bark.

The main factor for development is high relative humidity in orchards or forests. Fungi of this family prefer shaded areas with poor air circulation.

Persistent moisture on the trunk surface creates an ideal environment for spore germination and colony formation. This is often observed in orchards with excessive overhead irrigation.

Temperature plays a secondary role as these fungi show high plasticity, but their most active growth occurs during moderately warm seasons.

Crowded planting schemes also favor fungal spread, as restricted airflow slows the drying of bark after rain or dew.

Air quality is a crucial condition: the presence of these fungi often serves as an indicator of the absence of heavy chemical pollution, making them useful bioindicators of environmental health.

Fungi of the Monoblastiaceae family cause no direct harm to crop yield or tree development, as they are not obligate parasites of plant tissues.

Indirect risks may involve the creation of micro-habitats for bark-dwelling pests, which can seek shelter under the crustose lichen thalli during unfavorable conditions.

Through excessive growth, epiphytic microflora may contribute to micro-damage of the outer periderm layer, occasionally weakening the bark's protective functions.

In ornamental horticulture, heavy coverage of trunks with lichens reduces the aesthetic appeal of trees, which necessitates maintenance and cleaning.

In rare cases, excessive colonization might obstruct gas exchange through bark lenticels, which could theoretically slow down physiological processes in heavily colonized trees.

Prevention relies on maintaining optimal canopy density through annual pruning, which improves airflow and sunlight exposure on tree trunks.

Removing dead bark layers with specialized scrapers during the spring period significantly reduces the amount of epiphytes on tree trunks.

Applying lime wash to trunks is an effective way to suppress the growth of lichenized fungi by creating an alkaline environment unsuitable for them.

The application of copper-based fungicides during the dormant period provides a strong suppressive effect on the spread of fungal colonies on the bark.

• Thinning of plantings.
• Regular sanitary pruning.
• Mechanical bark cleaning.
• Lime washing of trunks.
• Application of copper-based fungicides.