Plowrightia circumscissa

Pathogen and disease type. Plowrightia circumscissa is an ascomycete fungus responsible for a serious bark-canker disease in stone fruit trees. This pathogen primarily attacks the vascular tissues and bark, leading to necrosis and significant structural damage to the affected woody stems.

Host cultures. The fungus is primarily known to affect species within the Prunus genus. Cherry and sour cherry are the most common hosts, though symptoms have been documented on apricots and plums, potentially leading to severe economic losses in commercial fruit production.

Symptoms and signs of infection. The disease manifests through the formation of black, swollen, and crusty lesions on twigs and branches. As the fungus spreads, these lesions develop into deep, open cankers that girdle the branches, often causing foliage wilting, tip dieback, and eventual death of the affected branch sections.

Development and spread conditions. Plowrightia circumscissa thrives in high-humidity environments and moderate temperatures, particularly during the early spring months. Spores are disseminated through rain splashes and wind, entering the plant host primarily through bark wounds, pruning cuts, or natural fissures in the woody surface.

Protection and control measures. Management strategies focus on sanitation, specifically the removal and burning of all infected branches during the dormant season. Preventive chemical control involves applying copper-based fungicides before bud break to protect healthy tissues and prevent new infections from establishing on the bark surface.

• Regular pruning to improve air circulation in the tree canopy.
• Sterilization of pruning tools between trees to prevent cross-contamination.
• Application of wound sealants on major pruning cuts.
• Monitoring orchards for early symptoms during spring and autumn.