European fruit tree canker

European fruit tree canker, caused by the fungus Neonectria ditissima, is a destructive disease affecting the wood and bark of various woody plants. It is particularly notorious in apple and pear orchards, where it causes significant economic loss by weakening or killing the trees through the formation of necrotic lesions.

The host range of this pathogen is broad, including various pome fruits, as well as many hardwood tree species such as beech, ash, and oak. Because it persists in the environment, the disease poses a perennial threat, making it a critical focus for orchard health management strategies throughout the growing season.

Symptoms of the infection present as sunken areas on branches and trunks, often surrounded by callus tissue that develops in concentric rings, forming a typical 'canker' appearance. As the fungus invades the wood, the bark cracks and peels, eventually leading to branch dieback or total collapse of the canopy. Fruit infections result in 'eye rot' or brown spots with fungal spores.

The infection cycle is heavily dependent on moisture and temperature. Spores are primarily dispersed by rainfall and wind, entering the tree through natural openings like leaf scars, pruning wounds, or frost-damaged tissue. The pathogen remains active in wood lesions throughout the winter, producing spores whenever temperatures and humidity are favorable, particularly during the autumn and spring.

Effective management requires a combination of sanitation and chemical interventions. Pruning out and destroying infected wood is the most vital step to remove inoculum. Growers should also ensure good orchard hygiene, protect wounds with paint or pruning sealants, and apply approved fungicides during the autumn leaf-fall period and the spring bud-burst phase to prevent new infections.