Pathogen

Fungus

Hosts

Potatoes

Symptoms

Concentric wrinkles develop on the tuber skin with white, pink or blue fungal patches. The rot inside the tuber is usually pale brown in colour with an undefined margin.

Development

The fungus is carried on seed tubers and can also survive in the soil for up to 7 years. Tubers are infected when inoculum in soil is impacted into wounds. Rotting usually develops late in storage as the temperature begins to rise.

Favourable Factors

Warm, humid storage conditions (12 - 20C).

Importance

One of the most important storage diseases of potatoes in the UK. In the growing crop a problem causing uneven emergence, reduced yields and variable tuber sizes.

Control

• There are no resistant varieties, but information on less susceptible varieties is available on the National List.

• Rotation of at least 5 years

• Plant disease free seed tubers

• Minimise mechanical damage

• Ensure a good skin set before lifting

• Store in cool, dry conditions

• Treating with fungicides may reduce disease incidence after lifting