Blight-resistant potato varieties help cut carbon footprints

Despite their strong blight resistance, Sárpo potato varieties remain very much a niche product. Could that be about to change? Robert Harris reports

Beauty may only be skin deep, but for the premium supermarket pre-pack market, appearance is everything.

Whatever other attributes a potato variety may have, only the best looking, bright-skinned tubers with shallow eyes, a regular shape and low dry-matter content make it on to the shelves.

That frustrates David Shaw, director of research at the Sárvári Research Trust, who tests and develops Hungarian-bred Sárpo varieties at the Henfaes Research Centre near Bangor, north Wales.

“The industry has worked itself into a lather over tuber finish. It has become the be all and end all in the fresh potato sector, yet most people peel the skins anyway,” he says.

Not that Sárpo potatoes are ugly – far from it, he insists. “Our best-known variety, Sárpo Mira, a maincrop introduced in 2002, has late foliage maturity and continues to bulk up if not stopped. If it is not properly managed towards the end of the season it can produce some strange-looking outgrades.”

The variety, which produces long oval red-skinned tubers when managed correctly, and its successors have struggled to shake off that reputation, even though newer varieties have a range of maturities, dry matters and skin colour, says Dr Shaw. As such, Sárpo varieties remain largely the preserve of amateur gardeners and small-scale organic producers.

“The supply chain says we are getting near to producing the modern waxy, white-skinned variety that today’s consumer wants. But they won’t trade excellent blight resistance for less-than-perfect appearance – to them blight is not a problem as it can easily controlled with a liberal use of chemicals.”

However, what is perceived as beautiful could be about to change. Supermarkets are examining much more closely the carbon footprint of goods that fill their shelves, including potatoes. Processors are also taking much more notice, with some establishing carbon audits.

Dr Shaw believes such moves could provide the breakthrough that has eluded Sárpo varieties. All have excellent or good resistance to late blight and viruses, removing the need for 15 or more sprays a season. This would significantly reduce a crop’s carbon footprint, he believes.

Sárpo Mira has retained a score of seven for foliar late blight and a nine for tuber blight, despite the arrival of the new aggressive Blue 13 strain first identified by Dr Shaw and fellow researchers in 2005.

More recent additions to the National List include Sárpo Gwyn, an early maincrop with medium dry matter, which also scores seven for foliar blight. Others include Sárpo Una, a second early waxy pink, waxy variety, salad type Kifli and blue-skinned Blue Danube, and another early maincrop, Sárpo Shona.

Although scores for foliar blight resistance are not the highest in these four varieties, one or two blight sprays will keep the crop in perfect health, Dr Shaw maintains.

The vigorous, weed-suppressing foliage common to Sárpo varieties often negates the need for herbicides, helping their environmental footprint further, he adds.

And their vigorous deep rooting reduces the need for energy-hungry irrigation and means they are good nutrient miners. Yield is another key determinant in the carbon footprint equation, and the typical 45-50t/ha output matches many modern conventional choices, he notes.

However, perhaps the biggest carbon trump card is their dormancy. Sárpo varieties can be stored at ambient temperatures for months. “They don’t need to be kept in cold stores. This could save a huge amount of energy and therefore carbon over a season,” says Dr Shaw.

“We are keen to investigate this further so we can prove that, far from being hair-shirt potatoes, these are low-input, low-cost potatoes suited to modern tastes with an exceptionally light carbon footprint.”

Seed pane

Although seed remains in tight supply, stocks of high-grade, certified Sárpo seed, both conventional and organic, are being multiplied by a group of mainly livestock farmers in north Wales and Scotland.

“Our virgin soils in north Wales are free of potato cyst nematode and the virus resistance of our varieties means that aphid transmission at sea level is not a problem,” says Simon White, Sárvári’s trials and seed manager. Two farms have Safe Haven status, he adds.

The venture is also set to benefit from a useful sideline. Jones o Gymru crisps, a premium hand-cooked product, was recently set up by a group of growers and entrepreneurs, to which Sárvári belongs, and will take over-sized grades from Sárpo seed growers.

The aim is to sell them through independent outlets and some supermarkets across the UK, says Mr White.

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