A growing number of potato farms in the UK are under restriction after the world's most damaging potato disease was discovered.
Miriam O'Reilly of Radio 4's Farming Today explains the effects of the disease, known as potato ring rot.
What is potato ring rot?
Potato ring rot is a highly infectious bacteria which is widespread in crops around the world.
It is the foot-and-mouth of the plant world.
How does it show itself?
The disease appears as black rings within the potato and the vegetable rots.
What does it mean for a potato crop?
Any infected crop would have to be dug up and destroyed.
The bacteria stays in the soil, so the farmer would not be able to replant until it was clear, which could take six years.
The spores also live on machinery and packaging.
How worried is the farming community about this?
Extremely - infected farms would not be able to trade and it is unlikely they would be insured against any outbreak.
If the disease took hold in the UK, all potato exports could be banned.
Where does it come from?
The origins of ring rot are unknown, but the disease only infects early potatoes.
Good surveillance in the UK has meant that in the past infected batches of seed potatoes have been found before they were planted.
Not every batch of imported potatoes is tested, and visual inspections are not foolproof as ring rot is hard to pick up with the naked eye.
In this case the infected batch got through to the farm and the seed potatoes were planted last season.
What can be done to combat the spread of the disease?
Any outbreak has to be contained as quickly as possible.
Infected farms are closed down, crops destroyed and any machinery or sacking which came into contact with the infected potatoes thoroughly cleaned.
It can be spread if infected potatoes are transported across the country to other farms.
Have there been previous cases of this disease in the crop in the UK and when?
No, this is the first outbreak to ever hit the UK.
It is known the infected farm sold seed potatoes to three UK farms, which are now under restriction, and exported more to the Canary Islands, Majorca and Spain.