Potato Brown Rot
Potato brown rot (Ralstonia solanacearum) is a serious bacterial disease of potatoes that is listed in the EC Plant Health Directive and is notifiable in the UK. It is caused by the bacterium Ralstonia solanacearum. It is widely distributed in warm temperate areas of the world and within the EC there have been findings in many Member States including Belgium, France, Germany, Hungary, Italy, The Netherlands, Portugal, Slovakia, Spain and Sweden.
There have been five outbreaks in England in ware potatoes between 1992 and 2000. The bacterium was found in Scotland in 2000, in water samples and in the alternative host, Solanum dulcamara, taken from a small stretch of the Tay river system in Perthshire during routine monitoring. The bacterium has now been successfully eradicated.
Despite intensive testing of potato crops following the finding of the bacterium potato brown rot has never been found in Scottish potatoes. Tomato crops are also susceptible and have been affected at a single location in England in 1997 and 1998.
Guidance and European Directives
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 (98/57) for the disease lays down measures aimed at preventing its spread wherever it is found and, if possible, eradicating it. The Scottish Government carries out annual monitoring of seed and ware potatoes and watercourses for the bacterium. Restrictions are imposed in the event of positive findings, which involve irrigation for watercourses and spraying prohibitions for potato and tomato crops.
A potato brown rot leaflet is available. A Scottish Government information sheet summarising action to keep Scottish potatoes free from potato brown rot is also available.
Potato brown rot information for England and Wales can be found on the Fera plant health website.