Cinnamon fungus

Cinnamon fungus, caused by the pathogen Pezicula cinnamomea, is a significant fungal disease affecting the bark of various woody plants. This pathogen typically functions as a wound parasite, invading the host through lesions, frost cracks, or improper pruning cuts. Once established, it compromises the structural and physiological integrity of the plant by damaging the cambium layer.

The host range of this fungus includes a variety of deciduous tree species. While it may infect mature, robust trees, it is notably more destructive to younger specimens or those already stressed by environmental factors, nutrient deficiencies, or pest infestations. The disease prevalence often increases in areas where trees are planted too densely, limiting airflow and sunlight.

Visual diagnostic signs include localized sunken lesions on the bark that typically appear brown or cinnamon-colored, corresponding to the fungus's common name. As the necrosis advances, the bark may rupture, leading to the formation of visible cankers. In humid environments, small, disk-shaped fruiting bodies (apothecia) appear on the dead bark tissue, releasing spores for further infection.

The spread of Pezicula cinnamomea is highly dependent on climate conditions. High humidity and cool, damp weather provide the ideal environment for spore germination and infection. Rain and wind are the primary vectors that carry the spores from infected necrotic tissue to healthy bark wounds, allowing the cycle of infection to persist throughout the growing season.

Effective management requires a proactive approach centered on hygiene and plant vigor. Removing and destroying infected branches is essential to reduce the local inoculum. Furthermore, protecting tree bark from mechanical injury and ensuring trees are adequately spaced to promote drying are critical cultural practices. In severe cases, protective fungicide applications following major pruning may be necessary to prevent the establishment of the pathogen.