Fisheye rot

Fisheye rot, caused by the fungus Butlerelfia eustacei, is a notable post-harvest disease affecting apple fruits. It is primarily observed after the harvest, significantly reducing the shelf life and market value of the crop. This pathogen is particularly problematic in environments where fruit handling causes even minor skin abrasions, providing easy entry points for fungal spores.

The causal agent, Butlerelfia eustacei, is an ascomycete fungus that thrives under moist conditions. It acts as a specialized parasite, penetrating the fruit epidermis through lenticels, insect punctures, or mechanical wounds incurred during harvest and transportation. Once inside, the fungus secretes enzymes that degrade the cellular structure of the fruit flesh.

The distinctive symptom of this disease is the development of circular, well-defined lesions on the fruit surface that resemble a "fish eye." These lesions typically feature a dark center surrounded by a lighter halo, creating a marked contrast with the healthy tissue. As the infection progresses, the underlying flesh becomes soft, discolored, and eventually turns into a sunken, rotted area that can encompass the entire fruit.

The development and spread of Butlerelfia eustacei are heavily influenced by environmental factors, particularly humidity. Excessive moisture during the pre-harvest period facilitates initial infection in the orchard, while poor air circulation within cold storage facilities can lead to rapid secondary spread between healthy and infected fruits. Stressed or overly mature fruits are more susceptible to colonization by this pathogen.

Effective management strategies against Fisheye rot require a multi-faceted approach centered on both field and post-harvest practices. Orchard sanitation is vital to reduce the initial inoculum of the fungus. Furthermore, post-harvest measures, including careful handling to minimize mechanical damage and the maintenance of strictly controlled environmental conditions in storage, are essential to mitigate the impact of this disease.

• Strict adherence to fungicide application schedules in the orchard.
• Minimization of skin punctures during harvest and grading.
• Rigorous culling of infected fruits prior to storage.
• Implementation of rapid cooling to stabilize the fruit temperature.
• Regular sanitation of packing lines and storage environments.