The potato harvest season runs from March to June
The remainder of the season's Jersey Royal potato crop could go to ruin if weather conditions do not improve.
Heavy downpours over the last two weeks have turned many of Jersey's potato fields into quagmires, bringing the harvest on some days to a standstill.
Tom Benet, managing director of Jersey Royal Potatoes, said it was "unprecedented".
Potatoes are the island's biggest export crop and the season, running from March to June, has one month left.
Mr Binet, whose company farms about 4,400 acres across Jersey, said: "I have never seen the likes of this in 17 years of farming.
"The ground is pretty saturated and we just can't get the potatoes out. It's unprecedented."
He estimates his company, which supplies most of the main UK supermarkets, has lost about 3,000 tonnes of orders.
Last year the potato seed crop was affected by bad weather in June and July, and farmers had been hopeful that this year would be drier.
According to the supermarket Tesco, Jersey royal potatoes account for 75% of all UK potato sales when they are in season, and the annual market is worth £35m.