Potato ring rot 
Potato ring rot is a serious non-indigenous bacterial disease of potatoes, which is listed as a quarantine organism in the EC Plant Health Directive and is notifiable in the UK. It is caused by the bacterium Clavibacter michiganensis ssp. sepedonicus.
It has been reported in a number of countries including parts of North America and is also established in northern and eastern Europe. There had been no outbreaks in the UK prior to a finding in Wales in November 2003.
Potato ring rot has never been found in Scotland.
Guidance and European Directive
The Plant Health Directive includes requirements on the movement of material within the Community, and on imported material, to prevent the spread of this disease. Additional measures may also be introduced in response to particular risks. The Directive is implemented in domestic legislation through the Plant Health (Scotland) Order 2005.
In addition, a specific EC Control Directive (93/85/EEC) for the disease lays down measures aimed at preventing its spread wherever it is found and, if possible, eradicating it. We carry out an annual survey of seed and ware potatoes for the bacterium. Restrictions are imposed in the event of positive findings and a contingency plan is in place outlining the measures to be taken..
A potato ring rot leaflet is available.
Potato ring rot information for England and Wales can be found on the Fera's Website.