Graphostroma platystomum

Graphostroma platystomum is a fungal pathogen belonging to the Ascomycota division, known primarily for causing bark necrosis in various broad-leaved tree species. As a specialized parasite, it targets the periderm and cambium layers, interfering with the physiological processes of the host plant and leading to localized tissue death.

The primary host for this fungus is the linden tree (Tilia). While it often colonizes trees that are already stressed or compromised by environmental factors such as frost damage or mechanical injuries, it can also manifest in dense stands where microclimatic conditions favor the accumulation of fungal spores.

The clinical signs of the disease include the formation of distinct, black, plate-like stromata that rupture through the host's bark. Beneath these structures, the necrotic tissue turns dark and brittle. Over time, these areas develop into sunken lesions or fissures, which can compromise the structural integrity of the branches and the trunk.

Development and spread are heavily influenced by environmental humidity and temperature. The fungus thrives in moist, temperate conditions that facilitate the production and release of conidia. These spores are easily disseminated by wind and water splash, allowing the pathogen to colonize adjacent trees if the environmental conditions remain favorable.

Integrated management is essential for controlling this disease. Key strategies include:

• Sanitary pruning of affected limbs to reduce inoculum pressure.
• Disinfection of pruning tools to prevent cross-contamination.
• Enhancing tree vigor through proper fertilization and watering.
• Application of protective fungicides during the early stages of infestation.