Neonectria canker

Neonectria canker, also known as European fruit tree canker, is a severe fungal disease caused by the pathogen Neonectria galligena. This fungus primarily attacks the bark and cambium of woody plants, leading to the formation of necrotic lesions and woody cankers. It poses a significant threat to orchard profitability by weakening trees and reducing fruit quality.

The disease affects a wide range of fruit-bearing trees, with apple and pear trees being particularly susceptible. Aside from pomaceous crops, the fungus can colonize various hardwood species such as willow, poplar, and oak. Infection typically occurs through natural openings like leaf scars or via physical wounds caused by pruning, insects, or frost damage.

The visual symptoms of the infection appear as sunken lesions on stems and branches. In resistant cultivars, these develop into concentric rings of callus tissue, known as an open canker. In susceptible varieties, the disease creates massive, dark, dead tissue areas that eventually cause branch girdling. Small, bright red perithecia (fruiting bodies) are often visible on the surface of the cankers during humid weather.

High rainfall and moderate temperatures are the primary drivers of spore dispersal and infection development. The fungus produces spores throughout the year, which are spread by wind and rain splashes. The pathogen survives the winter in the bark of infected branches, making it a persistent issue that can quickly spread throughout an entire orchard if not managed properly.

Effective management requires a combination of cultural and chemical strategies. Sanitation is crucial; all affected branches should be pruned back to healthy wood and removed from the site. Regular fungicide applications, particularly during leaf fall and early spring, help prevent new infections. Maintaining tree vigor through proper site selection and balanced fertilization significantly reduces susceptibility to the disease.

• Prune away infected wood at least 15 cm below visible lesions.
• Disinfect pruning tools between trees to prevent cross-contamination.
• Apply copper-based sprays during the dormant season.
• Ensure proper tree spacing for maximum airflow and light penetration.