The Potato Council has produced a definition of "new potatoes" that it hopes will be adopted by the industry following complaints from the public that the term was being misused by retailers.
An investigation by trading standards officers found that potatoes were being sold as "new" up to seven months after harvest.
Officers from South Ayrshire Council took 24 samples from six retailers earlier this year and found that each included potatoes harvested "quite some time" before going on sale.
One sample from Tesco had been harvested in August last year, but was still described as "new" while on sale in March. The council told the Potato Council, which agreed that a standard definition was lacking.
Head of marketing Caroline Evans said: "Our description of a 'new potato' means customers know they're enjoying potatoes at their seasonal best."
Tesco has agreed to abide by the definition. But Sarvari Research Trust director of research Dr David Shaw said: "Supermarkets are unlikely to stop calling a set-skin small potato anything but a new potato, no matter how long it has been stored."
Definition: What makes a new potato 'new'?
Under the Potato Council's agreed definition, "new potatoes" are those:
- defined as a first or second early in the British Potato Variety Database or the European Cultivated Potato Database;
- with an "immature, thin, or scraping skin";
- destined for retail sale without storage.