Fusarium dry rot of potato

Pathogen and disease type. Fusarium dry rot in potatoes is caused by the fungus Fusarium sambucinum. It is a serious fungal disease that significantly impacts both the growth phase in the field and the quality of tubers during the post-harvest storage period, often leading to total loss of infected batches.

Host range. The primary host is the potato plant, though the fungus can survive in soil debris for several years. It is highly opportunistic, readily infecting tubers through mechanical injuries, cuts, or bruises sustained during the harvesting and handling processes.

Symptoms and signs. In the field, infected plants show yellowing leaves, wilting, and stunted growth. On tubers, the disease appears as sunken, dark, wrinkled spots. When cut, the infected flesh is dry and brown, often with cavities lined with masses of white, salmon-pink, or yellow fungal mycelium.

Development and impact. The pathogen thrives in moist conditions with temperatures above 5°C. High humidity in storage combined with poor ventilation creates ideal conditions for rapid spread. The economic impact is devastating as it not only ruins current yields but also ruins the marketability and potential for seed stock.

Prevention and control measures. Management of the disease relies on integrated strategies:

• Minimizing physical damage to tubers during digging and grading.
• Implementing crop rotation with non-host plants to reduce soil inoculum.
• Curing tubers adequately after harvest to allow skin to heal.
• Maintaining optimal storage temperatures (2-4°C) with proper air circulation.
• Applying registered fungicide treatments to seed potatoes before planting.