The use of polytunnels has revolutionised soft fruit production in the UK, and the advantages vastly outweigh the drawbacks, according to the NFU.
Since the introduction of polytunnels 13 years ago, UK soft fruit growers have been producing increasingly successful crops, partly because they prevent rain damage to the developing fruit.
In an average year 40 per cent of the crop can be damaged by rainfall.
"Polytunnels have allowed British fruit growers to make huge advances, both in saving the ripening fruit from rain damage and in extending the season which now lasts from May until October," said Anthony Snell, NFU horticultural board member.
"The season used to last only six weeks but now it can last six months.
"British growers are now successfully competing with foreign imports from Egypt and Spain, extending the growing season has a big impact on the food miles that used to be attached to strawberries before June and after July."
Demand for strawberries, a rich source of vitamin C as well as antioxidants like ellagic acid, has increased in the UK, with many supermarkets marketing the fruit as one of nature's Superfoods. Strawberry sales in the UK are reported to have increased by 34 per cent during the last two years.
Growing public understanding of several fruits and vegetables has also seen demand increase across the UK for other berries. Sales of blueberries are reported to have rocketed by 130 per cent, while raspberry sales grew by 62 per cent in the last two years.
Polytunnels are plastic structures developed from similar designs used by farmers in Spain to protect their winter salad crops. They consist of a tubular steel framework of hoops over which polythene is secured.
The moveable tunnels are erected and dismantled by farm staff or horticultural contractors at the end of each growing season - a maximum period of six months of any year.
The enclosed nature of polytunnels means that the growers can reduce their use of pesticides by 50 per cent and the enclosed environment means they can also release natural enemies like lacewings to eat aphids and other pests.
"The British soft fruit industry is worth 185 million every year and that is down to the improved conditions that polytunnels offer the plants."
There has been criticism of polytunnels because of their visual impact on the landscape. But the NFU argues that recently developed plastics have helped to reduce the glare and shimmer by 70 per cent.
In addition, there are environmental advantages to using polytunnels. Domestic supermarkets represent 85 per cent of the British retail business. Farmers who cannot meet quality standards are 'de-listed' or dropped as a supplier.
When adequate UK sources are exhausted berries from Spain, France and America are imported, with greater damage to the environment in the form of high food miles.
Analysts from Innova Market Insights said recently that the increasing popularity of berries and berry flavours is now extending to other less well-known super fruits, such as pomegranate, mangosteen, acai and noni, which are all being marketed on their antioxidant content and associated health benefits.
This could have a knock-on effect into other sectors. Datamonitor recently said that in Europe, the increased popularity of exotic fruit contributed significantly to a growth rate of 26 per cent for the European organic food industry between 2001 and 2004. The US market looks to be following suit.