Supplies of common British vegetables will run short this autumn as the extended dry spell takes its toll on crops, growers have warned.

Even household staples such as potatoes will be in short supply, but buyers appear unconcerned by widespread reports of shortages and price hikes.

NFU horticulture board chairman Richard Hirst said that there were early signs that volumes of main crop potatoes due to be lifted this autumn will be 20% lower than usual.

Prices for the small volumes traded outside contracts have risen steadily to about £80 per tonne more than in 2005. Jersey Royal new potatoes were the first to suffer, with exports down 8,000t this season.

Peas and beans were said to be down 20% while brassicas could be down 40%. "If we'd had only an inch of rain in June it would have changed the picture completely - it's that fine a line between a good or average crop," said Hirst.

One southwest grower predicted a difficult autumn. "Cauliflowers are dying in the ground and we've lost acres so far. The broccoli has been stressed right out and gone to flower. We've had to pick our way through it for saleable crop. The spring greens seed isn't out of the packet yet because it's too dry. Usually, it would have been in the ground two weeks ago for harvesting in November."

The situation is being worsened by similar problems in Continental Europe, with industry groups predicting falls of up to 40% on some crops.

But supermarket buyers remained bullish. A spokeswoman for Sainsbury's described it as a '"storm in a vegetable basket", while Waitrose said it was not an issue at present. Tesco said: "The potential impact of the recent hot dry weather is something of which we are aware and we are working with suppliers to ensure availability and quality."