The infectious potato disease Dickeya solani has been found in a ware crop growing in Perthshire.
The species is an aggressive, form of the seed-borne bacterial disease, blackleg
Scotland had recently established rules to keep the disease out.
But reports in The Scotsman newspaper suggested that a Dutch-bred variety had been brought north from England and planted in a potato seed growing area in Coupar Angus, Perthshire.
The infection is currently limited to one field on one farm and was picked up as part of a Scottish Government inspection, according to the newspaper report.
The crop has been destroyed but growers are on alert because the bacterium can survive in soil and spreads through water courses.
Dickeya solani was first identified in 2005 and in less than five years has become the predominant cause of blackleg in continental Europe. It has been blamed for a five-fold increase in annual losses from the disease amounting to €25m.
It is the major reason for seed downgrading and rejections in the Netherlands through the related condition of bacterial soft rot of tubers.
The disease has never been found in potatoes grown from seed of Scottish origin.