Phacidiopycnis tuber rot

Phacidiopycnis tuberivora is a fungal pathogen responsible for a specific type of dry rot in potatoes. Unlike soft rots caused by bacteria, this disease manifests as a progressive desiccation of the tuber tissue, significantly impacting the commercial quality and nutritional value of stored potatoes.

The disease primarily affects potato tubers. The fungus is soil-borne, and primary infection occurs either in the field before harvest or immediately after, through wounds and natural openings like lenticels. Once inside, the fungus colonizes the parenchyma, leading to the disintegration of internal starch structures.

The visual signs of the disease include sunken, dark lesions on the tuber surface. As the infection progresses, the internal tissue becomes spongy, brown, and dry. A definitive diagnostic feature is the presence of pycnidia, small black reproductive structures of the fungus, which often emerge through the skin of the rotting tuber.

Environmental conditions during storage are critical to the proliferation of the disease. Temperatures ranging between 5°C and 15°C, combined with high humidity, create an ideal climate for the fungus to spread. Poor ventilation in potato bins exacerbates the situation by allowing moisture to accumulate, creating hotspots of infection.

Effective control strategies focus on integrated management. Key measures include harvesting under dry conditions to minimize wounding, removing infected tubers before long-term storage, and ensuring proper curing of the potato skins post-harvest. Maintaining storage temperatures strictly below 4°C is essential to inhibit the growth of the pathogen and preserve crop integrity.