Cytospora canker of plane tree

Cytospora platani is a pathogenic fungus belonging to the Ascomycota division, known primarily as the causal agent of canker disease in plane trees (Platanus). This fungus is a facultative parasite that aggressively exploits weakened tissues, leading to the formation of localized necroses that can girdle stems and cause branch death.

The primary hosts of this pathogen are various species of the Platanus genus. The disease manifests as sunken, dark-colored areas on the bark, which eventually crack and become necrotic. Over time, these areas become site-specific focal points for the fungus, where small, erupting pycnidia appear, releasing masses of conidia that serve as the primary source of inoculum.

The life cycle of the pathogen is closely tied to environmental conditions. Cytospora platani survives the dormant season as mycelium within infected wood. During periods of high humidity and moderate temperatures, the fungus produces conidia, which are disseminated by rain splash, wind, and insects. Infection occurs primarily through wounds, pruning scars, and winter-damaged bark tissues.

The development of the disease is heavily influenced by host susceptibility. Stress factors, such as drought, sunscald, frost damage, or poor soil conditions, significantly reduce the tree's ability to resist the fungal invasion. Once the pathogen colonizes the phloem and cambium, it causes progressive bark death, which can be fatal if the main trunk becomes girdled.

Control strategies for Cytospora canker focus on sanitation and tree health management. Effective practices include:

• Prompt removal and destruction of infected branches.
• Sterilization of pruning equipment to prevent cross-contamination.
• Application of wound dressings to large cuts.
• Improving tree vigor through proper irrigation and nutrient management to aid natural defense mechanisms.