Fenestella

The most distinctive sign is the development of necrotic areas on the bark, characterized by a series of small, perforated openings.

These openings are the exit points for the fungus's reproductive structures, which give the affected bark a perforated or "window-like" appearance.

As the infection progresses, the bark becomes discolored, develops deep cracks, and the underlying cambium tissues begin to die.

Visible symptoms often include localized gumosis and the gradual dieback of specific branches in the canopy.

• small perforated bark holes;
• necrotic bark patches;
• bark cracking;
• dieback of branches.

The disease is caused by the ascomycete fungus Fenestella fenestrata, which typically acts as a weak parasite on woody plants.

The fungus is primarily adapted to colonizing weakened plant tissues, where it establishes its mycelium under the bark layers.

During its life cycle, it forms small, embedded fruiting bodies called perithecia, which are responsible for releasing infectious spores.

Spores are dispersed through the air and splashing water, allowing the fungus to spread throughout orchards and forests.

The pathogen is highly persistent, capable of surviving for long periods in dead wood, which serves as a reservoir for further infection.

High humidity and poor air circulation in the canopy provide the ideal environmental conditions for the fungus to thrive.

Mechanical damage to the bark from pruning or environmental stress, such as frost cracks, provides entry points for the pathogen.

Temperatures ranging from 15 to 25 degrees Celsius promote optimal growth rates for the fungus within the host tissues.

Densely planted orchards often suffer from higher infection rates due to reduced airflow and increased moisture retention on stems.

Tree stress caused by drought or improper mineral nutrition significantly lowers the host's defenses, allowing the fungus to colonize.

The primary impact of the disease is the systematic dieback of branches, which drastically reduces the photosynthetic capacity of the tree.

If the infection reaches the main trunk, it can lead to severe structural damage and the eventual decline or death of the entire tree.

Economic losses occur due to decreased fruit production, the cost of labor for surgical tree intervention, and possible tree replacement.

The disruption of vascular tissues prevents efficient nutrient transport, leading to stunted growth and reduced cold hardiness.

Infested trees become susceptible to secondary infestations by wood-boring insects, further accelerating the degradation of the plant.

Effective management requires rigorous sanitation, including the prompt removal and disposal of all infected wood and branches.

All pruning wounds should be treated with appropriate fungicides or protective sealants to prevent spore germination at the site of injury.

Preventative applications of copper-based fungicides in early spring can help suppress the fungal population on the bark surface.

Promoting tree health through balanced fertilization and adequate irrigation is crucial for maintaining strong natural immunity.

Regular inspection of the orchard is essential to identify early symptoms and take immediate steps to contain the spread of the fungus.