EPPO Global Database

EPPO Reporting Service no. 04 - 1999 Num. article: 1999/056

Isolated finding of ring rot in Dutch potato crop

During a routine test carried out by the Dutch NPPO, bacterial ring rot (Clavibacter michiganensis subsp. sepedonicus - EPPO A2 quarantine pest) has been discovered in Dutch seed potatoes. It is the first time that this disease has been found in Dutch potatoes. An in-depth investigation into the cause of the outbreak has been carried out. All the information currently available suggests that this is an isolated infection.

In order to combat the disease each member state of the EU is carrying out research into the incidence of bacterial ring rot. Ring rot had not previously occurred in Dutch potatoes, but the disease was present in a number of other member states including Germany and Denmark. This had prompted the Netherlands to intensify its tests for ring rot in recent years. Approximately 7,500 samples of potatoes from the 1997 harvest were tested and found to be free from the disease. 7,100 samples from the 1998 harvest have so far been tested. The presence of ring rot in one sample of the Ottena race has been confirmed. This sample comes from a consignment of seed potatoes grown from own seed in the province of Overijssel close to the German border. All clonally related consignments have been tested and found to be free from ring rot. There is no evidence of any spread of the disease in the Netherlands.

The measures to eradicate the contamination and prevent the spread of the disease have been taken in accordance with the EU requirements. This means among other things that the contaminated consignment has been destroyed, that the other consignments of seed potatoes from the infected farm are no longer designated as seed potatoes, and that the contaminated land may not be used for growing potatoes for a period of three or four years.


NPPO of the Netherlands, 1999-04, updating the press release from the Dutch Ministry of Agriculture of 1999-01-12.