a potato affected by late blight fungus

The top 5 fungal diseases in UK potatoes

Potatoes are susceptible to a lot of fungal infections, threatening crop yields and profits. Understanding the causes and treatments of these diseases is crucial for growers. From environmental factors to effective control methods, this guide provides insights into combating fungal infections in potatoes, ensuring healthier crops and sustainable farming practices.

In the UK, the top 5 fungal diseases affecting potatoes and their treatment methods are:

  1. Late Blight (Phytophthora infestans): Originating from infected plant debris or seed potatoes, late blight thrives in cool, moist conditions. It spreads rapidly, causing dark lesions on foliage and tubers. Treatment involves timely fungicide applications, cultural practices like crop rotation, and planting resistant potato varieties.
  2. Early Blight (Alternaria solani): Early blight spores overwinter in infected plant debris and soil. Warm, humid weather encourages its growth, resulting in dark lesions on lower leaves. Treatment includes fungicide applications, proper irrigation to avoid leaf wetness, and removing infected plant material.
  3. Powdery Scab (Spongospora subterranea): This disease originates from infected tubers or soil. It causes powdery lesions on tubers, reducing their marketability. Management involves using resistant potato varieties, improving soil drainage, and applying fungicides like mancozeb during tuber development.
  4. Fusarium Dry Rot (Fusarium spp.): Fusarium spp. infect potatoes during storage, especially in warm, humid conditions. Dry, sunken lesions develop on tubers, leading to decay. Control methods include proper storage conditions (cool and dry), using disease-free seed potatoes, and applying fungicides.
  5. Silver Scurf (Helminthosporium solani): Helminthosporium solani survives in infected tubers and soil. It causes silvery lesions on potato tubers, reducing their market value. Treatment involves planting disease-free seed potatoes, using fungicides, and proper crop rotation to manage its spread.

What causes fungal infections in potatoes?

Humid and moist conditions create perfect environments for fungal pathogens like late blight and early blight to thrive. Blight fungal spores mainly come from infected plant debris and spread through the air, carried by the wind. Soil-borne fungi, including Rhizoctonia solani causing black scurf and Verticillium dahliae causing Verticillium wilt, pose risks to potato crops.

Additionally, planting infected seed potatoes introduces pathogens into the soil, making disease spread easier.

How to manage fungal infections

  • Crop Rotation: Alternating potato crops with other plants disrupts the life cycles of fungal pathogens, reducing their prevalence in the soil.
  • Sanitation Practices: Removing and disposing of infected plant debris reduces the chance of fungal spores overwintering and re-infecting crops.
  • Fungicide Applications: Regular application of fungicides containing active ingredients such as copper and mancozeb helps control fungal infections, especially during periods of high disease pressure.
  • Selection of Resistant Varieties: Planting potato varieties with genetic resistance to specific fungal diseases reduces reliance on chemical controls and minimises disease impact.
  • Optimal Irrigation Management: Proper irrigation practices, including avoiding over-watering and ensuring adequate soil drainage, create less favourable conditions for fungal growth.

To keep potatoes healthy and safe from fungal diseases, use a mix of methods. Rotate crops, source high quality seed potatoes that are free from disease, and apply fungicides if required. Check your crops often and act fast if you see any problems.