Chestnut fusicoccum canker

The pathogen responsible for this disease is the fungus Fusicoccum castaneum, which belongs to a group of microorganisms known for causing necrotic cankers on woody plants. This fungus primarily attacks the bark and cambium layers, interfering with the plant's vascular system and causing significant physiological stress.

Sweet chestnut (Castanea sativa) is the primary host species for this pathogen. The fungus typically enters the tree through physical injuries in the bark, such as frost cracks, pruning wounds, or damage inflicted by insects and herbivores, which serve as entry points for the fungal spores to colonize the healthy tissue.

Symptoms of Fusicoccum castaneum infection include localized necrotic lesions on the bark, which appear sunken, darkened, and often cracked. In advanced stages, one may observe the formation of small, dark fruiting bodies (pycnidia) breaking through the bark surface, releasing spores during periods of high humidity or rainfall.

The development and spread of this disease are heavily favored by humid and moderate environmental conditions. Spores can be disseminated over short distances by water splash or over longer distances by wind. Trees under environmental stress, such as drought or poor soil nutrition, are notably more susceptible to the successful colonization of the pathogen.

The economic and ecological impact of the disease is significant, as it leads to progressive branch dieback and, in severe cases, the death of the entire tree. Effective management strategies involve a combination of cultural and chemical practices:

• systematic pruning and removal of infected branches;
• proper disinfection of all pruning tools to prevent cross-contamination;
• application of copper-based fungicides to protect vulnerable bark areas;
• maintaining overall tree vigor through adequate irrigation and fertilization.