Potato Cyst Nematode (PCN) is the primary pest of potato within the UK and infestation can result in tuber yield losses that exceed 80%. Overall, the pest is estimated to cost the UK potato industry about £50 million annually.

The main period of plant damage is caused when juvenile nematodes emerge from cysts and infest plant roots.  PCN infestation can cause wilting, stunted growth, and other symptoms which are widely indicative of root damage and stress.

In England and Wales, approximately 65% of the land used for growing ware potatoes is infested with PCN.

Understanding PCN

There are two PCN species, white PCN (Globodera pallida) and yellow PCN (G. rostochiensis), with the former being the most common.

A PCN cyst can contain 200-600 eggs and once present in the soil can persist for over ten years. The eggs are stimulated to hatch by potato root exudates.

Once land is infested with PCN, it is very difficult to eliminate so management strategies generally concentrate on maintaining pest numbers at levels where they have a minimal impact on the crop.

Assessing the level of PCN infestation

Understanding the level of PCN infestation in your land is pivotal to developing a successful management strategy.

Before planting, it is important to assess the overall PCN risk within a given field. The presence of PCN cysts, along with cyst viability and the species composition, influences the overall risk and decides which pest management options can be employed.

Chemical control with one of a range of nematicides is most commonly used. Where the yellow PCN (G. rostochiensis) is most common, resistant potato varieties can be grown. Cyst viability is also an important factor to consider, as a high number of unviable cysts containing few PCN eggs presents less risk than a low number of viable cysts which contain many eggs. Furthermore, the presence of any PCN cyst will mean that the land cannot be used to grow seed potatoes or potatoes for export.

When to check for PCN

PCN levels in the soil are often assessed between September and March before planting the new crop. This allows the determination of the extent of the PCN risk so that appropriate management practices can be employed if needed. In some cases, the results of PCN analysis will be used to help make decisions on whether or not to rent land for cropping with potatoes.

How to test soil for PCN

ADAS Pest Evaluation Services offers a PCN screening service which provides a count of PCN eggs/g soil, PCN cysts/100g soil, viability assays, and expert advice. For more information, please email pes@adas.co.uk

About the ADAS Pest Evaluation Services team

The Pest Evaluation Services team, based in North Yorkshire, specialises in all aspects of nematology, entomology, and pathology over a range of arable and horticultural crops.

Comprising of entomologists and laboratory technicians, the team has over 50 years of combined entomological and pathological experience, and regularly participates in wider ADAS Research & Development projects.