Rosellinia thelena

The primary symptom of infection is a change in the bark structure, which becomes loose and eventually detaches from the trunk.

Under the dead bark, the development of mycelium, appearing as white or grayish fan-shaped strands, is often observed.

On the surface of the dead wood areas, one can notice small, dense black dots, which are the fruiting bodies of the fungus.

The plant begins to show signs of general decline: leaf chlorosis, premature needle or leaf drop, and the drying of individual branches.

In advanced cases, there is complete necrosis of the cambium tissues, leading to the rapid death of the entire branch or even the entire tree.

The causative agent of the disease is the fungus Rosellinia thelena, which belongs to the class Ascomycetes. This microorganism leads a saprotrophic or weakly parasitic lifestyle, colonizing weakened plant tissues.

The fungus forms black, rounded fruiting bodies known as perithecia on the surface of the substrate, which are often found in clusters.

The mycelium of the fungus actively spreads under the bark of infected plants, gradually penetrating into deeper layers of wood.

The biology of this pathogen is closely linked to the decomposition of organic matter, making it a typical inhabitant of forest ecosystems.

Spore dispersal occurs primarily through the air, and the fungus can remain viable in plant debris for a long period.

The development of Rosellinia thelena is favored by high humidity in the air and soil, creating optimal conditions for spore germination.

The fungus most often attacks trees that are in a state of physiological stress due to drought, pests, or mechanical injury.

The presence of large amounts of uncleared plant debris in gardens or forest stands provides a primary source of infection.

Poor aeration of plantings and excessive planting density promote moisture stagnation, which triggers mycelial growth.

Moderate temperature ranges are favorable for the metabolism of this fungal species.

The damage caused by this pathogen lies in the gradual destruction of the bark and cambial layer, which disrupts the normal flow of sap in the tree.

Long-term infection leads to a serious decrease in the aesthetic value and productivity of woody plantings.

In tree nurseries or young orchards, the infection can cause mass mortality of seedlings due to their weak immune system.

Infected wood loses its quality characteristics, becoming unsuitable for use in construction or woodworking.

The disease significantly weakens the tree, making it vulnerable to secondary pests such as wood-boring insects.

A key method of prevention is timely sanitary thinning and the removal of infected plant parts from the plantings.

It is necessary to avoid mechanical damage to trunks and roots, as the fungus easily penetrates tree tissues through such wounds.

It is recommended to maintain optimal agronomic practices aimed at strengthening plant immunity: regular watering, fertilization, and pest protection.

• Perform timely cleaning of dead bark.
• Ensure good ventilation of tree crowns.
• Destroy infected plant residues by burning.

If the use of fungicides is necessary, the choice of preparation should be based on recommendations for controlling fungal bark diseases.