Blue mold rot

The causative agent of the disease is the fungus Penicillium crustosum, a widely distributed saprophytic pathogen belonging to the group of imperfect fungi. This infectious disease, commonly known as "blue mold," affects mainly fruits and vegetables during the ripening stage, as well as throughout the transport and storage phases.

Major crops susceptible to infection include pome and stone fruits, particularly apples and pears, as well as citrus fruits and various root vegetables. The pathogen invades plant tissues through any mechanical injuries to the skin, which typically occur during harvesting, sorting, or transportation of the produce.

Symptoms of the infection manifest as rapidly expanding soft, slightly sunken lesions on the fruit surface. Over time, these areas become covered with a dense, characteristic layer of conidiophores, which appear as blue-green or turquoise powdery spores. The affected fruits often develop a distinct musty, unpleasant odor.

Development and spread of the pathogen occur most intensely in high-humidity conditions (above 85%) and moderate temperatures. The fungus is thermotolerant and exhibits the ability to grow actively even at the low temperatures found in industrial cold storage facilities, representing a significant challenge for postharvest crop maintenance.

The economic impact of the disease is severe, resulting in total loss of marketable produce and the risk of accumulation of dangerous mycotoxins, such as penitrem A. Effective control strategies involve: sanitation of storage facilities, strict humidity management, careful handling to minimize bruising, and the application of postharvest fungicides.