Blue mold

Blue mold is a destructive post-harvest disease caused by various species of the fungus Penicillium. This pathogen is a classic opportunistic wound parasite that primarily invades fruits and vegetables through mechanical injuries, bruises, or cuts occurring during harvest and post-harvest handling.

The fungus has an extensive host range, frequently affecting onion, garlic, asparagus, papaya, citrus, watermelon, strawberries, and sweet potatoes. Because the spores are easily airborne, a single infected fruit can serve as a massive inoculum source, leading to rapid disease spread throughout the entire storage facility or container.

Symptoms initially appear as soft, discolored spots on the skin. As the disease progresses, these spots are covered by a characteristic dense mass of blue-green or turquoise powdery spores. The underlying tissue becomes watery and decayed, often emitting a distinct musty or moldy odor, eventually leading to the total breakdown of the fruit structure.

Environmental conditions are critical for the development of blue mold. High relative humidity (above 85%) and poor ventilation in storage are the primary drivers of disease outbreaks. Additionally, cool temperatures do not necessarily stop the growth of Penicillium; some species are well-adapted to low-temperature environments, making them particularly dangerous in cold storage.

Effective management requires a comprehensive approach, starting with careful handling to minimize skin damage. Sanitation practices, such as disinfecting storage crates and rooms, along with maintaining optimal airflow and humidity control, are essential.

• Sort produce meticulously before storage
• Remove all infected materials immediately
• Maintain proper cooling and ventilation systems
• Apply recommended post-harvest fungicides where necessary