Potato blight, that caused the Irish potato famine, is an airborne disease that can devastate a crop.
The Potato Council said the fungal disease, that manifests itself as a mould on the leaf and roots, has hit the potato crop badly this year due to the wet weather.
‘Allotment amateurs’ were also blamed for a "disproportionate amount of overall blight pressure."
Inexperienced gardeners could make blight spread by dumping infected potatoes on the compost, where the spores can spread on the wind to neighbouring farms.
In contrast commercial farms regularly spray the crop with fungicide to stop infection and bury any infected potatoes.
Allan Stevenson, Chairman of the Potato Council, told trade journal The Grocer, that people should be buying potatoes from the supermarket rather than growing their own as this may help spread blight.
"People should be encouraged to grown their own vegetables to learn about the origins of their food,” he said. "But the blight risk is real and it would be preferable if people bought healthy, well produced potatoes from their retailer rather than grow their own."
The wet weather has added even more to the cost of potatoes as farmers have struggled to harvest the crop in the wet ground. The cost of fuel, fungicide and fertiliser is also rising.
The wholesale price of potatoes, as a result of the poor harvest, has gone up by 61 per cent in the last year and there are fears this could be passed onto the customer, especially as wider food prices also rise.
The Potato Council is working with the Royal Horticultural Society and the National Society of Allotment and Leisure Gardeners (NSALG) to produce a special blight fact sheet and educate gardeners about the disease.
Even though the average home or allotment plot of potatoes is likely to be very small, the airborne infection can soon transfer from a garden to a commercial field of the crop.
Gardeners tend to grow lots of different varieties, some of which are more susceptible to potato blight than commercial strains.
As soon as the fungus is spotted on leaves, the potatoes should be buried underground, burned or sent to council recycling units that use closed composting. Otherwise the spores will spread on the wind to farmers’ crops.
There are 330,000 allotments in Britain, with a further 90,000 people on the waiting list for a plot.
B&Q and other retailers have reported a rise in sales of seeds for food since the recession as more people grow their own.
A spokesman for NSALG insisted that their members were aware of how to deal with blight and it was unfair to 'tarnish everyone with the same brush".
“People being able to grow their own should be celebrated," she said. "Like everything else people should be supported and educated about the right and wrong ways to deal with things but I would say our members are fairly well educated in knowing how to deal with pests and diseases. It is unfair to tarnish everybody with the same brush.”
