Dermea canker

Initial symptoms are characterized by small, sunken necrotic lesions that form on the bark of trunks, branches, or twigs.

As the infection progresses, the affected bark shrinks, turns dark brown or black, and may exhibit a rough, wrinkled surface texture.

Small, dark-colored fruiting bodies of the pathogen may erupt through the bark surface in clusters within the necrotic zone.

Foliage distal to the infected branch may show signs of chlorosis, curling, and premature defoliation as the vascular supply is restricted.

Severe infections often lead to girdle-like cankers, resulting in the total dieback of the branch or death of the entire tree if the trunk is affected.

The causal agent of Dermea canker is the ascomycetous fungus Dermea cerasi, which primarily infects stone fruit trees, including cherries.

The fungus overwinters as mycelium and fruiting bodies (pycnidia and apothecia) within the infected bark and wood tissues of the host plant.

During the growing season, especially under humid conditions, the fungus produces conidia which facilitate the primary and secondary infection cycle.

Pathogen dispersal typically occurs via rain splash, wind currents, and mechanical transmission through contaminated pruning tools.

The fungus is opportunistic and exploits wounds, sunscalds, or unhealed pruning cuts to invade the vascular system and colonize healthy tissues.

High relative humidity and frequent rainfall are critical factors that promote spore germination and successful colonization by the fungus.

Trees subjected to environmental stress, such as frost injury or drought, show increased susceptibility to Dermea infection.

Dense orchard spacing and poor canopy aeration create a humid microclimate that favors the rapid multiplication of the pathogen.

Neglecting to disinfect pruning tools after working on infected wood significantly increases the risk of spreading the disease across the orchard.

Optimal temperatures for fungal growth generally range from 15 to 22 degrees Celsius, coinciding with spring and autumn growth flushes.

The disease causes significant economic losses by reducing the structural integrity and longevity of cherry trees in commercial orchards.

Infected trees suffer from reduced vigor and diminished fruit quality due to the impaired transport of water and nutrients throughout the canopy.

Extensive canker development leads to branch dieback, which necessitates heavy pruning and can eventually render the tree unproductive.

Once established in an orchard, the disease acts as a persistent inoculum source, threatening neighboring healthy trees if not properly managed.

The cost of replacing killed trees and implementing intensive control programs significantly impacts the profitability of fruit production.

Strict sanitation practices, including the removal and destruction of all cankered wood, are the foundation of effective disease management.

Pruning cuts should be made well below the visible necrotic tissue to ensure complete removal of the internal fungal mycelium.

Proper wound healing should be promoted by applying protective paints or fungicides to all major pruning cuts immediately after the operation.

• Application of copper-based sprays during the dormant season to reduce spore pressure.
• Sanitizing pruning shears between trees to prevent the mechanical transmission of the pathogen.
• Maintaining tree health through proper fertilization and irrigation to improve natural defense mechanisms.

Regular orchard monitoring is essential to detect early symptoms, allowing for immediate intervention before the infection becomes systemic.