The low prices retailers are paying cauliflower growers are threatening the long-term viability of English production.

Growers of the brassica crop, largely produced in the south west in winter, are receiving only 18p-20p per head for a crop that can cost up to 35p per head to produce, according to Richard Hirst, chairman of the National Farmers' Union horticulture board.

"If growers can't have a bigger share of the retail value to reward them for their work, they'll go and do something else," he warned.

Hirst said the union was collecting data and planned to hold discussions with supermarket buyers once it had been collated.

Retailers and the public should know growers were not simply "crying wolf", he added. "Five years ago growers were receiving 41% of the retail value, now it's about 20%."

Last year's floods meant cauliflower plantings had to be delayed from June and July to August, causing the season to get off to a slow start. The late winter crop then overlapped with the spring crop, which, when combined with warmer winter temperatures boosting production levels, created a surplus.

This has led to a situation where some cauliflowers have been left unharvested in fields in Cornwall.

Growers have also faced increases in production costs, with fertiliser and energy prices rising significantly in the past year. "Supermarkets are maintaining margin and not supporting growers. Some growers say they will reduce their plantings or get out of production altogether next season if the price doesn't go up," said Richard Angove, senior group secretary for the West Cornwall NFU branch.

Many growers were seriously considering switching to more profitable cereal crops, he added.

Total UK expenditure on cauliflower was £99m last year, up 4% year-on-year [TNS]. This rise was largely due to price increases and promotions, said TNS.