Hazelnut cytospora canker

Cytospora corylicola is a significant fungal pathogen responsible for cytospora canker on hazelnut and filbert trees. It acts as an opportunistic parasite, primarily targeting the bark and cambium layers of the branches, eventually causing severe tissue necrosis and tree decline.

This pathogen specifically affects plants within the Corylus genus. Orchard health is often compromised when the pathogen infects branches that have been weakened by environmental stressors such as drought, winter cold injury, or poor management practices that leave trees vulnerable.

Typical symptoms include the development of discolored, sunken areas on the bark. As the disease progresses, these lesions enlarge, eventually girdling the branch. Small, pimple-like structures known as pycnidia erupt through the bark surface. During wet weather, these structures release spores that spread the infection to adjacent branches or neighboring trees.

The development and spread of Cytospora corylicola are highly dependent on moisture levels and host vigor. Spores are easily disseminated by rain splashes and wind, entering the host through fresh mechanical wounds, frost cracks, or pruning cuts. Once established, the fungus grows internally, disrupting the plant's vascular system.

Management of the disease requires an integrated approach focusing on prevention and sanitation. Pruning should be conducted during dry weather, and all diseased wood must be removed and destroyed to reduce inoculum pressure. Maintaining vigorous tree growth through appropriate fertilization and irrigation, combined with the protection of pruning wounds using fungicidal sealants, is critical for successful control.