Mucor rot

Mucor rot is a destructive fungal disease caused by the pathogen Mucor piriformis. As a member of the Zygomycetes class, this fungus is a significant post-harvest threat, capable of causing rapid decay in a wide variety of fruits and berries. Its ability to proliferate quickly makes it a major concern for fruit producers and storage facility managers alike.

The disease primarily targets pome and stone fruits, such as apples, pears, and peaches, as well as strawberries. Mucor piriformis acts as a wound pathogen, meaning it typically requires a portal of entry to colonize the host. Mechanical injuries, insect feeding punctures, or microscopic cracks in the fruit cuticle provide the perfect environment for the fungus to initiate infection.

Symptoms of the disease are characterized by the rapid development of soft, watery, and decayed lesions on the fruit surface. As the infection progresses, the internal tissue breaks down completely, often resulting in a distinct fermenting odor. A dense, fluffy, whitish-gray mycelial mat soon covers the affected area, eventually developing dark sporangia that release large quantities of spores.

The epidemiology of Mucor piriformis is heavily influenced by humidity and temperature. A key concern for the industry is that this pathogen is psychrotrophic, meaning it can continue to grow and cause significant decay even at temperatures close to freezing. This allows the disease to spread extensively within refrigerated storage environments, leading to substantial economic losses.

Effective management and prevention of Mucor rot require an integrated approach focusing on sanitation and handling:

• Careful harvesting to avoid bruising or wounding the fruit skin.
• Strict hygiene protocols in packing houses and storage facilities.
• Removal of orchard debris to reduce the primary inoculum pressure.
• Optimizing airflow and maintaining low humidity during fruit storage.
• Use of appropriate post-harvest treatments to inhibit fungal growth.