Neofabraea rot

Neofabraea rot, commonly known as bullseye rot, is a fungal disease caused by species of the genus Neofabraea. It is a significant concern for pome fruit growers, as it primarily causes post-harvest fruit decay that can result in substantial economic losses during storage and transportation.

The primary hosts for this pathogen are apple and pear trees. The fungus behaves as a necrotrophic pathogen, colonizing both the fruit and the woody tissues. While the damage to fruit is most visible, the ability of the pathogen to establish cankers on limbs makes it a persistent threat that cycles within the orchard ecosystem.

The clinical symptoms on fruit manifest as circular, depressed brown lesions, often with a lighter or cream-colored center, giving the appearance of a "bullseye." As the lesion matures, the tissue underneath becomes decayed and often develops a bitter taste. Infected limbs may show sunken cankers, which serve as the primary inoculum source for subsequent seasons.

The development of the disease is heavily influenced by cool, wet weather conditions, particularly as the fruit approaches harvest. Conidia (spores) are dispersed by rainfall and wind. Even at low temperatures, such as those found in commercial cold storage facilities, the fungus remains active, leading to widespread infection if not managed correctly in the orchard.

Integrated management strategies are essential for reducing the incidence of bullseye rot:

• sanitary pruning to remove wood cankers;
• application of targeted fungicides during the late growing season;
• monitoring nutrient levels to avoid excessive tree vigor;
• post-harvest handling, including rapid cooling to inhibit fungal growth.