Nicola Sturgeon has accused the UK government of selling out farmers in Scotland after it emerged that seed potatoes are set not to be included in a post-Brexit trade deal. A letter from the Department for Environment, Food and Rural Affairs (Defra) said the EU would allow almost all food and plant exports from Great Britain to continue from 1 January. However, seed potatoes will be banned. The Defra letter says: “Unfortunately the EU have confirmed they will not accept our case for a permanent change to the prohibition on seed potatoes … on the grounds that there is no agreement for GB to be dynamically aligned with EU rules.” Scottish seed potato farmers are one of the biggest exporters for the production of chips and crisps in the world, with the sector accounting for three-quarters of UK production and worth about £112m a year. Northern English farmers will also be particularly affected. Sturgeon, Scotland’s first minister, tweeted: “This is a disastrous Brexit outcome for Scottish farmers … and like all other aspects of Brexit, foisted on Scotland against our will.” James Withers, the chief executive of Scotland Food and Drink, said: “There’s no dressing this up. This is bad news for Scottish seed potato exporters. One-fifth of our exports go to the EU, more than 20,000 tonnes a year. “It may be a smaller industry in a big trade deal, but tell that to the companies and farmers affected. This will feel to them about as far from a definition of free trade as is possible. There are still markets elsewhere and a roll-on deal for Egypt is good news.” Sales to Northern Ireland, which will operate under EU arrangements under the terms of last year’s withdrawal agreement, are also likely to cease. Iain Barbour, who manages JBA Seed Potatoes in Dumfries, described the outcome as “a massive disaster for everyone”. Pointing out that Scottish seed potatoes are a premium global product on a par with salmon or whisky, he added: “We’ve got so many people – potato trade bodies, Defra, MPs – supposed to be lokoing out for our interests but nobody has done.” Barbour, who has been selling seed potatoes to Northern Ireland and the EU for decades, said: “Nothing has changed in our potato rules so it doesn’t make sense to me how they can say we don’t align anymore.” Barbour said Scotland specialised in producing varieties such as Kerr’s Pink and British Queen, which suit Irish tastes. “We’ve seen demand for those double in the past month, because buyers knew there was a danger that they wouldn’t be able to get them after December 31st.” The Scottish National party’s shadow environment, food and rural affairs spokesperson, Deidre Brock, said: “If these reports are true, it would be a terrible negotiating failure on the part of the Tory government – and a devastating blow to an extremely valuable part of Scotland’s booming farming industry. “It is clear that the Tories are selling Scotland’s farming and fishing industry out and planning a total betrayal of our rural communities – with a hard Brexit that will cause serious and lasting damage to exports, jobs, living standards, businesses and the economy.”