Canker stain of plane

Pathogen and disease type. Canker stain of plane is a devastating vascular wilt disease caused by the ascomycete fungus Ceratocystis platani. It is recognized as a major quarantine pathogen globally. The fungus invades the tree's vascular system, specifically the xylem, where it produces toxins and physical blockages that severely impede water transport, ultimately leading to the tree's death.

Host range. The disease primarily targets trees within the genus Platanus, including the London plane, Oriental plane, and American sycamore. The pathogen is extremely virulent; once a tree is infected, the fungus spreads systematically through its internal tissues, meaning that even a minor infection point can become fatal within a few years.

Symptoms and signs. Early symptoms include foliage wilting, yellowing, and premature shedding. As the disease advances, cankers—depressed, elongated lesions—form on the bark. If the bark is removed, the underlying wood reveals characteristic dark, reddish-brown to black staining, which is a diagnostic feature of this fungal pathogen.

Development and spread. The fungus thrives in a wide range of temperatures, particularly in warm and humid conditions. It spreads through human activity, primarily through contaminated pruning tools, machinery, or the transport of infected wood products. Furthermore, it spreads underground through root grafting, where roots of adjacent trees fuse and allow the fungus to pass directly from one host to another.

Control and prevention measures. Because there is no known cure for the canker stain of plane, management strategies focus exclusively on prevention and containment:

• Strict sanitation protocols for pruning tools using fungicides or alcohol-based disinfectants.
• Immediate removal and professional disposal (burning or burying) of infected trees.
• Enforcement of strict quarantine regulations on the movement of Platanus wood and nursery stock.
• Avoidance of any mechanical wounding to healthy trees during maintenance work to prevent entry points for spores.