Dothiorella canker

Dothiorella canker, caused by the fungus Dothiorella foederata, is a serious disease that primarily affects the bark and vascular system of woody plants. As an ascomycete fungus, it colonizes the cambium, disrupting the tree's ability to transport nutrients and water, which ultimately leads to limb dieback or whole-tree mortality.

This pathogen has a wide host range, commonly impacting fruit trees like apple and pear, as well as various ornamental shrubs and forest species. The disease is opportunistic, frequently manifesting in trees that have already been stressed by environmental factors or mechanical injuries.

Symptoms typically include sunken, discolored patches on the bark, which may eventually crack or peel away. Beneath these lesions, the inner bark and sapwood show signs of necrosis, turning brown or reddish-black. In advanced stages, small, pimple-like pycnidia emerge from the necrotic tissue, releasing spores to spread the infection.

The fungus thrives in moist environments, with spore dissemination facilitated by splashing rain and high humidity. Wounds from pruning, frost cracks, and insect feeding provide ideal entry points for Dothiorella foederata, allowing the fungus to establish itself and proliferate within the host's tissues.

Effective management and prevention strategies include the following:

• Rigorous sanitation, including the removal and destruction of infected wood.
• Proper pruning techniques to minimize open wounds and improve airflow within the canopy.
• Application of protective copper-based fungicides during the dormant season.
• Maintaining tree vigor through balanced fertilization and appropriate irrigation to boost immunity.
• Protection of trunks against winter sunscald and bark-damaging pests.