THE FRENCH CONTROL SCHEME AGAINST RALSTONIA SOLANACEARUM
De Guénin1 M.C., Caffier2 D.
1
2 Laboratoire National de la Protection des Végétaux Unité Bactériologie. 10, rue Le Nôtre, F-49044 Angers Cedex 01.
With regards to the European phytosanitary regulation, Ralstonia solanacearum is a quarantined bacterium. Each member must apply strong measures in order to avoid the introduction and the dissemination of the disease, and to eradicate it in case an outbreak occurs. The French Plant Health Service decided to strengthen the control scheme against brown rot in order to keep the country free from the disease.
Since 1993, an official document, the European Phytosanitary Passport, has been linked to the lots. It gives the main information concerning the lot and assures that it is consistent with the requirements of regulations. Farmers do have to keep the passport for at least three years so that the origin of an outbreak could be traced. Nevertheless, all the Dutch potatoes are carefully controlled by the French Plant Health Service because of the outbreaks which occurred in the Netherlands. Inspectors check that the passport is present and take samples for analysis.
Importation of seed tubers from third countries to the European Union is forbidden, except from Switzerland. Extensive tests are performed in the French potato quarantine station in case some plant material is required for research or breeding.
Only Cyprus, Egypt, Hungary, Israel, Libya, Malta, Morocco, Switzerland, Syria, Tunisia and Turkey are allowed to export ware potatoes to France. Controls are done according to their phytosanitary status. All the lots coming from known contaminated countries are controlled. In addition to visual observations on cut tubers, one sample consisting of 200 tubers per lot of 25 tons or less is analysed. Potatoes coming from countries where brown rot was described in the past are inspected and samples are analysed. Controls are done at random on ware potatoes coming from countries where the disease was never reported. Contaminated lots are sent back or destroyed.
Field inspections and laboratory tests are extensively done in France during breeding and multiplication of seed potatoes in order to guarantee that tubers are free from a list of harmful organisms, including R. solanacearum. The production of ware potatoes is also controlled, samples are collected at random and submitted to analysis.
Some of the outbreaks which occurred in Europe seem to be connected with irrigation and potato processing industries. It is not possible to test extensively all the rivers, so the risks are evaluated according to acreage of susceptible plants in each region, irrigation with river water and existence of potato or tomato processing industries in the neighbourhood. Each Regional Plant Health Service is then asked to collect a number of samples according to a risk scale. Samples of water or of wild Solanum dulcamara growing by the riverside are sent to the laboratory.
In the meantime, the laboratory is preparing new antisera and is testing and comparing different methods to prepare samples and to detect the bacterium in solanaceous plant material, weeds, soil and water. Extensive investigations are held in areas where an outbreak occurred in order to check that the disease is strictly controlled.
