Farming leaders are calling for urgent talks with the Conservative shadow Minister for the Environment, Food and Rural Affairs after he criticised the use of polytunnels for growing soft fruit.

Bill Wiggin, MP for Leominster in Herefordshire, said his constituency was being covered in a sea of plastic, making it difficult for people living next to them to sell their homes.

He said he had not eaten a strawberry for four years and anyone eating the fruit out of season was encouraging the blight of polytunnels on the landscape.

But farmers have hailed the structures a success, claiming that without them this year's crop of strawberries would have been ruined by May's heavy rainfall.

The National Farmers' Union said 1,700 tonnes of the crop had been saved by polytunnels this year worth £85 million.

The NFU West Midlands is calling for a meeting with Mr Wiggin to address his concerns and highlight the importance of the structures for the region's farming economy.

The union has also set up a conference later this month, inviting MPs to a Herefordshire farm to discuss the use of polytunnels in the area.

Mr Wiggin said: "In Herefordshire, polytunnels do not have to have planning permission and we have got thousands of acres of plastic.

"We have a huge tourist industry here and visitors want to see the good side of British agriculture but can't see it if it is under plastic."

Mr Wiggin said the proliferation of polytunnels had knocked 25 to 30 per cent off the value of their homes.

Jenny Ellerton, of the Wickton Action Group, an anti-polytunnel group in Herefordshire supported by local resident and TV gardener Monty Don, said: "The size and scale of these developments are out of all proportion to the landscape around them.

"The tunnels should get planning permission, just as we need planning permission to alter our houses.

" I don't believe local authorities do enough to regulate this. Where are our democratic rights? We can't afford to take Herefordshire Council to court over this, and the tunnels seem to be continuing to expand. It might be a success at one level, but at what cost to human lives and the environment?"

Anthony Snell, who is hosting the conference with MPs on his farm in Harewood End, Herefordshire, said the use of polytunnels was vital if the industry was to compete with foreign imports.

"The soft fruit industry used to be a real struggle. Our season was squeezed into barely two months - June and July.

We had low yields of truly marketable product, with mis-shapen fruit that suffered from short shelf-life.

"We're now producing much more class one fruit. Before tunnels, we were looking at 40 per cent, now it's more like 80 per cent."

In 2005, sales of British strawberries and raspberries sold through UK supermarkets rose by 17 per cent to £157 million. Ten years before, British soft fruit was seen as an unreliable product, beset by bad weather and prone to disease and damage.

Mr Snell's crops include 140 acres of strawberries, raspberries, blackberries and blueberries, packed mainly for Sainsburys.

He said: "Finding a good site is key, that's blended into the landscape, is away from houses and has natural barriers to soften the visual impact. "We are worried for the future as a vociferous minority can cause problems. Some people see the countryside purely as their 'view' and would prefer it to be a museum.