The Scottish strawberry industry is facing crisis after experts said farmers could have lost up to £10 million this summer due to poor weather.

Thousands of plants have had to be discarded after being killed by heavy frost in the winter, while many more are not ripening because of a lack of sunshine. Others have been plagued by fungal diseases that thrive in wet conditions.

Some soft fruit farmers are now fearing for the future of their businesses as demand from major retailers plummeted during recent dreary weather.

Peter Thomson, chairman of the soft fruit division of NFU Mutual, said soft fruit farmers were experiencing very difficult times, which had been exacerbated by a late harvest.

Mr Thomson, who employs around 300 people at West Haugh Farm near Blairgowrie, Perthshire, said he understood Scotland's £50m strawberry industry could have shrunk by as much as 20% as a result.

He said: "It's a double whammy, really – we have much increased costs when we have lower yields but there is also diminished demand from the supermarkets. It is costing soft fruit farmers all an awful lot of money, definitely millions of pounds.

"In these conditions, it becomes very difficult to produce the super-quality fruit that you see on the shelves in your supermarkets."

Mr Thomson added: "It's difficult to pick fruit properly in this kind of weather, which increases costs and means there is more chance of some of it going mouldy. When this happens, we have no choice but to throw those strawberries away.

"People are also less inclined to buy summer fruits when it is so rainy."

Most of Scotland's strawberries are produced in late June and early July, but this year the harvest has been delayed, causing further problems for growers who can only hope for an upsurge in the latter part of the season.

Mr Thomson said many farmers would be considering the future of their businesses, adding that some had not experienced a successful season for the last six years.

Dr Rex Brennan, who heads the fruit breeding group at the James Hutton Institute at Invergowrie, outside Dundee, said all soft fruits had been affected.

"It has been a very challenging season," he said.