Prices have fallen 8.8% in the past 12 months, and are 0.4% lower than in the last survey on January 16 this year.
Onion prices in particular are on a spiral downwards - they have fallen for the fifth survey in a row and are now at their lowest recorded level. Of the ten items surveyed, seven are cheaper than a year ago.
This comes at time when energy prices are rising and pushing up the cost of production for UK suppliers.
NFU chief horticultural adviser Phil Hudson said: “If retail prices are down the suspicion is that growers’ returns are down, too. For the protected crop sector energy is a major input and this is putting further pressure on margins. The profitability of the industry is being damaged because the industry cannot reinvest, which threatens the viability of the sector.”