Growers are being urged to test potato land for potato cyst nematode (PCN) levels and ensure soil sampling is intense and accurate.

Sampling soil is an important part of formulating a PCN control strategy, giving growers an idea of numbers, species of nematode and any hotspots in the field.

Potato expert John Keer of Richard Austin Agriculture says a sample rate of one per hectare is the optimum testing intensity, which the most forward-thinking growers are currently using.

His concern is that many growers are still using just one sample per field or one sample for every four hectares.

“You can be even more robust than one per hectare, which will provide you with more information, but it won’t affect what you do agronomically.

“Research and experience tells us that rate will give you the best return on investment and reduces the risk of underestimating or missing PCN problems completely,” explains Dr Keer.

The two major species of PCN, Globodera rostochiensis and Globodera pallida, cost the potato industry in excess of £50m annually and are the biggest pest threat for potato producers.

Dr Keer points out that in such a high value crop, robust soil sampling is worthwhile, even when land is perceived as being “clean” and free from PCN.

“The overall cost of GPS sampling and PCN analysis is about £30/ha, which isn’t much in a crop that’s costing more than £6,000/ha to grow, yet the impact of a PCN problem can be massive if you get it wrong.”

Adding GPS recording of sampling sites is also adding value, says Dr Keer, as it provides a consistent analysis of the same locations in the field.

“It allows you to monitor how your PCN control strategy is performing over a longer period of time and you can making changes accordingly,” he adds.

Hutchinsons root crop specialist Darryl Shailes says even low levels of PCN can have a significant negative impact on crop health, increasing susceptibility to diseases such as alternaria and ultimately reducing yield and quality.

He also believes the sampling should be as thorough as possible and when taking an aggregate sample across one hectare, growers should aim for about 50 separate cores.

“The more samples you take the better chance you have of picking up on PCN hotspots,” says Mr Shailes.

Soil sampling is an integral part of an integrated strategy that is required to protect potato land from building PCN populations and can influence rotation width, variety choice and chemical or biological control measures.

With good potato growing land hard to find and expensive to buy or rent, Mr Shailes says it is vital it is protected for future production. 

“Controlling PCN is not just about the effects on the following crop,” he adds.

Soil fumigant metam sodium and conventional nematicides Vydate (oxamyl) and Nemathorin (fosthiazate) are under threat from regulatory pressure due to their hazardous nature. 

Dr Keer says that soil sampling will also ensure that those products are targeted as accurately as possibleto keep on top of PCN populations.

“We’ve all got to ensure PCN levels are kept as low as possible to grow the crop sustainably in the future.

“We believe thatPCN sampling once a hectare gives the optimum balance between time, cost and providing enough information to control PCN effectively,” he says. 

More on this issue