Potato Cyst Nematode (PCN) remains a critical challenge for UK potato growers. Effective management strategies require informed decision-making, responsible nematicide use, and selection of resistant and tolerant varieties.
Insights from the PCN Action Scotland project, led by Dr James Price at the James Hutton Institute, underline the importance of soil testing and variety choice, as the foundation of a robust PCN management strategy.
Start with your soil
Ahead of the 2025 planting season, Dr Price, a molecular biologist and nematologist, emphasises the importance of understanding soil and PCN populations.
“You need to know what’s in your soil at PCN species level—whether it’s Globodera pallida or Globodera rostochiensis. Without this knowledge, it’s impossible to deploy the right management strategies effectively.”
Soil testing enables early detection and identifies species type, helping growers make informed decisions about resistant varieties and the responsible use of nematicides where they are needed.
Dr Price stresses precision in sampling techniques to account for PCN’s elusive nature.
“You’re testing a small soil sample relative to the field area, and cysts are tiny—half a millimetre in size. Sampling appropriately is crucial to accurately identify the population.”
Integrating resistant potato varieties for PCN control
Understanding the difference between resistance and tolerance is key in making the best choice in variety:
- Resistance: Reduces the PCN population in the soil, gradually cleaning up infected land
- Tolerance: Maintains crop yield under infection pressure but does not reduce PCN populations.
- “For lower PCN populations, now is the time to introduce resistant varieties while the yield may remain relatively unimpacted.
“Impact on yield can be seen from as little as ten PCN per gram of soil,” says Dr Price.
“Therefore, if sampling indicates pressure into and above ‘double digits’, growers should consider the role of resistant and tolerant varieties to reduce PCN populations in the soil while also maintaining yield.”
Granular nematicides also play an important role in protecting that yield against the pest, but informed and responsible use is key.
“Nematicides don’t reduce PCN populations; they ‘freeze’ juvenile nematodes, preventing them from entering the plant during early development, allowing the plant to sustain a yield,” says Dr Price.
“Once the chemical is no longer present, the nematodes can resume activity, infect the plant and multiply
“Therefore, while nematicides protect yields under heavy infection pressures, they can mask the problem by maintaining yield, while PCN populations will continue to multiply.
“A true IPM approach, using resistant varieties where you can and extending crop rotations are both tools that can be used to reduce population buildup,” he adds.
If PCN pressures indicate that granular nematicides such as fosthiazate are needed, following the NSP Best Practice Guidelines is key to protect both the environment and operator safety.
Relevance of Scottish research
Although PCN Action Scotland’s findings stem from trials in the Scottish nation, their relevance extends to all UK growers explains Dr Price.“Our research impacts the entire industry. PCN is a huge, national problem, and Scottish seed growers play a pivotal role in controlling it by ensuring resistant varieties can be planted into infected land across the country.”
By adopting resistant varieties, growers can reduce the need for chemical intervention, delivering environmental benefits and lowering costs. This aligns with the NSP’s commitment to sustainable practices.
Key tips for controlling PCN
Start with soil testing: Early detection through soil sampling is essential to identify PCN species and population levels
Use resistant and tolerant varieties: Base decisions on population levels, choosing varieties suited to specific species (G. pallida or G. rostochiensis)
Take an IPM approach: For high pressures, pair resistant varieties with granular nematicides to protect yield. Extend crop rotations where appropriate. Consult your agronomist for advice specific to your farm and fields
Further information
Read more about PCN Action Scotland here: Home Page | Potato Cyst Nematode HubClick here to read the NSP best practice steps for the application of nematicides Code of good practice for the application of nematicides
