Neofabraea kienholzii

Neofabraea kienholzii is a fungal pathogen responsible for significant damage to pome fruit trees, primarily apples and pears. It is recognized as one of the causative agents of bull's eye rot and various bark canker diseases, posing a major threat to both orchard productivity and post-harvest storage quality.

The host range of this fungus is specialized towards the Rosaceae family. The pathogen affects the woody parts of the tree, such as branches and trunks, as well as the fruit. Infections often remain latent in the fruit during the growing season and develop into characteristic rot symptoms only after the harvest, while the fruit is in cold storage.

Symptoms on the bark include depressed, discolored lesions that eventually develop into deep, perennial cankers with raised margins. On the fruit, the disease manifests as circular, brown, slightly sunken spots. Over time, white or cream-colored sporulating structures emerge from the center of these lesions, which is a hallmark diagnostic feature of the fungus.

The development and spread of Neofabraea kienholzii are heavily influenced by environmental conditions, particularly cool, wet weather. The fungus survives the winter in the bark cankers and in mummified fruit left in the orchard. Rain splashes are the primary mechanism for spore dispersal, while wind can also play a role in spreading the infection to healthy tissues.

The economic impact of this disease is two-fold: direct yield loss in the field due to tree decline, and devastating losses during storage. Once infected fruit is placed in storage, the fungus can easily spread to neighboring healthy fruits, leading to widespread decay and significant financial loss for growers and packers alike.

• Remove and destroy all cankered branches and mummified fruit during winter pruning.
• Apply copper-based fungicides during the dormant season to reduce inoculum.
• Implement timely protective fungicide sprays during the growing season.
• Ensure adequate orchard hygiene by clearing leaf litter and fallen fruit.
• Maintain optimal storage conditions, including proper temperature and humidity control.