Nectria canker

Systematic position and pathogen nature: Nectria galligena is an ascomycete fungus classified as a serious phytopathogen. It is known as the causative agent of European fruit tree canker. The pathogen is highly persistent, capable of surviving for long periods in the bark of infected branches and stems of its hosts.

Host plants and diseases: This fungus primarily targets pome fruits, with apple and pear trees being the most susceptible. In addition to fruit trees, the pathogen can infect various deciduous trees, including ash, beech, and oak, which acts as a reservoir for spores that can infect neighboring orchards.

Biology and life cycle: The fungus enters the host plant through wounds, such as pruning cuts, leaf scars, or frost damage. Once established, the pathogen colonizes the bark and cambium layers. It produces spores (conidia and ascospores) that are dispersed by wind and rain, particularly during cool and wet weather conditions, allowing for recurring infections throughout the growing season.

Development conditions and economic impact: High humidity and cool temperatures are ideal for the development and spread of Nectria galligena. The disease causes significant damage by forming necrotic cankers on limbs and trunks, leading to limb dieback, reduced fruit quality, and eventual death of the tree if left unmanaged, causing major economic losses for fruit growers.

Protection and control measures: Management of the disease relies on integrated strategies to minimize infection sites and reduce inoculum pressure.

• Pruning and destroying infected branches to prevent further spread.
• Disinfecting pruning tools between trees to avoid mechanical transmission.
• Applying fungicides, particularly copper-based formulations, after pruning and during leaf fall.
• Maintaining optimal orchard hygiene and ensuring good air circulation to reduce humidity around the trees.