Phialophora rot

Systematic position and type of pathogen. Phialophora malorum (syn. Cadophora malorum) is a microscopic fungus classified within the kingdom Fungi, phylum Ascomycota, order Helotiales. It is primarily recognized as a post-harvest phytopathogen capable of causing significant decay in pome fruits during cold storage.

Diseases and host crops. The pathogen is responsible for Phialophora rot, also referred to as deep-pitted or spot rot. While it primarily infects apples, pears are also susceptible to this fungal invasion. The disease manifests as dark, depressed lesions on the fruit surface, which eventually extend into the flesh, causing softening and a bitter taste, rendering the produce commercially worthless.

Biology and life cycle. The fungus exists in the orchard environment on decaying leaves and plant debris. Infection typically occurs at the time of harvest or during handling, when spores enter the fruit through lenticels, micro-cracks, or physical damage caused by harvesting tools and sorting machinery. The pathogen remains latent initially and begins active colonization once the fruit is placed in storage conditions.

Developmental conditions and impact. The pathogen thrives in high-humidity environments and is well-adapted to the low temperatures maintained in industrial cold storage facilities (typically between 0°C and 5°C). The economic damage is severe because the infection often spreads rapidly from infected fruit to healthy ones, leading to heavy losses during the winter and spring months when the fruit is in storage.

Protection and control measures. Management of Phialophora malorum focuses on sanitation and minimizing fruit injury. Key strategies include:

• Applying pre-harvest fungicides to reduce the inoculum level in the orchard.
• Ensuring careful handling during harvest and post-harvest grading to prevent skin damage.
• Sanitizing storage bins, pallets, and packing facilities to reduce spore survival.
• Maintaining optimal cooling regimes with controlled humidity to slow down fungal growth.
• Regular inspection and sorting of stored fruit to remove early signs of infection.