Potato growers are facing an uncertain future unless contract prices increase, following a 25% drop in production and an increase in costs of 30%.
The NFU says that with about 75% of all potatoes grown on fixed-priced contracts, growers have borne the brunt of the large financial penalty dealt by the unprecedented cold and wet summer weather.
Yields are down and with thousands of acres of crops lost to waterlogged and flooded fields, production has fallen by a quarter nationally.
Tim Papworth, NFU potato forum chairman, said: "I can't remember a year quite like this. Our members have been working exceptionally hard to try to meet their customers' requirements, but the reality is that we have exceptional producers in this country suffering significant financial losses that were completely out of their control."
Mr Papworth warned many growers were now considering producing cereal crops instead of potatoes due to their higher current value, comparatively simpler supply chain and less intensive labour demands.
The Westcountry, though, has fared considerably better than most other regions.
Philip Prior, from Perranwell, near Truro, who grows 1,200 acres of potatoes said: "We haven't seen waterlogging in the way that they have upcountry because of the topography of the land in the South West. In the North and Midlands they still have potatoes to lift. Will they get them in? I wouldn't like to say."
He stressed, though, that he had never known such a difficult season, with very little rain in the first three months, and ten times as much in the remaining nine.
But salad potatoes, grown largely in the Westcountry, were less affected than main crop – down 20%.
"It's been a very unusual set of circumstances, but it could have a knock-on effect next year, with a shortage of seed potatoes, which are grown predominately in Scotland and Yorkshire," Mr Prior added.
The dry spring and appallingly wet summer have had an impact on other vegetables as well as potatoes.
Swedes and Brussels sprouts, grown extensively in West Cornwall, will be in tight supply, according to grower David Simmons. His family firm is part of Riviera Foods, based at Connor Downs, near Hayle, which takes produce from 12 local growers.
He said: "The situation is made serious by the fact that there are not the huge surpluses of vegetables that used to be grown not so long ago, which means that these days there's a big impact when there's adverse weather, such as we've experienced this year."