Eelworm threat to key Scots seed potato crops

On the surface all seems well in the Scottish potato industry with prices this year providing a good and occasional excellent financial return to growers but there is a problem lurking in the soil which might affect future prospects. The problem comes from potato cyst nematodes (pcn) that can reduce yields and remove markets for seed potato growers as they require to test their land before planting to ensure it is free from pcn.

According to Jon Pickup from the Scottish Government Science and Advice for Scottish Agriculture (SASA) which carries out the testing, there are currently some 20,000 acres of land infected with eelworm and thus out of seed potato production.

Yesterday he had blunt words for potato producers at a meeting held in the James Hutton at Invergowrie: “I think pcn will seriously compromise the area of land we can grow potatoes on in the future unless we change our ways.”

This eelworm “epidemic”, which is how Pickup described it, lies in all the main potato growing areas of the country, with Angus the heartland of the Scottish potato crop also havingthe highest levels of pcn infestation.

There are two main species of pcn – Globodera rostocheinsis and Globodera pallida – and the county of Angus has the highest incidence of the latter.

Using SASA records to track the development of the problem Pickup said that since 1970, there had been a steady increase in rostochiensis but the same period had seen a rapid increase in pallida infected land.

Part of the disparity in infestation has been down to new varieties being bred that have a resistance to rostochiensis but not to pallida and, given a free rein, the latter parasite has multiplied.

Adding weight to his concerns Pickup said that the situation was only going to get worse. He expected the acreage of land infected with Pallida would double in the next seven years. “It is already dialled in” was how he saw the problem as testing was always in a catch up situation.

And if that was not bad enough, he foresaw another doubling of Pallida infestation before the end of the 2020s.

“Current control methods are not working,” he stated.

However, Colin Herron, general manager of Mccain Foods, was more sanguine about the future saying that, while there was a problem with eelworm and it was not going to disappear, he was confident that new varieties coming forward would help to provide the answer.

“One of the main focus points we have as a company going forward is in introducing eelworm resistance and some of the varieties coming through the programme are quite promising,” he said.