Eutypella canker of plum

Eutypella canker is a serious fungal disease caused by the ascomycete Eutypella prunastri. This pathogen is known for causing localized necrosis and canker lesions on the bark and woody tissues of stone fruit trees. If left unmanaged, the infection can persist for years, severely damaging the tree's vascular system and leading to crown dieback.

The disease primarily affects species within the genus Prunus, with plum trees being particularly susceptible. The fungus enters the host through wounds, such as pruning cuts, frost cracks, sunscald injuries, or other physical damage. Once established, the mycelium colonizes the cambium and inner wood, slowly expanding the infected area over several growing seasons.

Key symptoms include depressed, sunken areas or raised callus tissue forming cankers around the site of infection. As the canker expands, the bark often cracks or peels away, exposing the necrotic wood underneath. A diagnostic feature is the presence of numerous small, black, pin-head-sized fruiting bodies (perithecia) embedded in the dead bark surrounding the canker.

Environmental conditions that favor the disease include high humidity, frequent rainfall, and mild temperatures, which facilitate the release and germination of fungal spores. Wind and rain are the primary vectors for dispersing spores throughout the orchard. Trees that are stressed due to poor soil, drought, or improper pruning are significantly more vulnerable to colonization by this pathogen.

The economic impact is significant, as the disease reduces fruit yields and can kill entire trees by girdling the stems or branches. Implementing a robust management program is essential for maintaining orchard health:

• Regular sanitation pruning to remove and destroy infected wood.
• Disinfecting pruning tools between trees to prevent the mechanical spread of spores.
• Promptly painting large pruning wounds with protective fungicidal wound dressings.
• Improving orchard air circulation through proper tree spacing and thinning.
• Applying preventive fungicide sprays during the dormant season and spring growth stages.