Health officials are examining a mid Wales farm - the source of the world's most damaging potato disease previously not found in the UK.
Middleton Farm in Bwlch is the focus of the investigation
It is thought they may begin destroying crops at Middlewood Farm in Bwlch, near Brecon, whjere tubours were found to be contaminated with ring rot - described as the potato equivalent of foot-and-mouth.
The discovery of the disease was confirmed during an annual survey for ring rot by Defra and it is thought the disease was brought into Wales on infected Dutch seed.
Although ring rot poses no risk to human health, farmers leaders in Wales had said the news is a "massive blow" to the industry.
Annual losses to US potato farmers caused by ring rot have been as high as 50%.
Farmers are also worried about the effect on the seed market if the UK loses its disease-free status.
Wales' potato industry
95 registered growers
Produces 86,000 tonnes
Worth £11.4m to economy
Total area farmed 2,000 hectares
John Morgan, the farmer at the centre of this outbreak said: "Obvoiusly we're devastated at the news. We're working with the Welsh assembly locally and Defra plant officials to eradicate this disease."
Officers from Defra , the Welsh assembly and the Plant Health and Seeds Inspectorate are meeting at the farm in the Brecon Beacons to assess the extent of the problem.
Farmer John Morgan says he's devastated by the news
It is likely crops will have to be burnt or buried.
Meanwhile, experts are trying to trace the movement of seed potatoes from the farm - it is known that the farm has exported to the Canary islands, Majorca and Spain and supplies a vast area of Pembrokeshire in west Wales.
The Welsh Agricultural Statistics 2002, compiled by the Welsh assembly, states that 2,295 hectares are used for potato growing in Wales.
According to the Farmers Union of Wales the total number of farms producing potatoes, is 651.
Brecon and Radnor MP Roger Williams said the priority was the eradication of the disease.
"I know the producers concerned have an excellent reputation for crop husbandry and health and I am sure that this outbreak will not be traced to any negligence on their part," he said.
"In that case we must look at the testing regime for potato imports particularly from Holland. I have tabled oral and written questions to Defra and will pursue this matter and any compensation that may be appropriate."
Assembly Conservative leader Nick Bourne called on Countryside Minister Carwyn Jones to make an urgent statement to the assembly
" Ring rot is a highly contagious disease which will devastate the potato industry if it is not contained," he said.