Potato brown rot in western Europe – history, present occurrence and some remarks on possible origin, epidemiology and control strategies

Abstract

Since 1992 an increased number of outbreaks of potato brown rot, caused by the bacterium Ralstonia (Burkholderia, Pseudomonas) solanacearum race 3, biovar 2, has been reported in several EPPO member countries, including more northern states like Belgium, France, The Netherlands and the UK. The largest outbreak took place in The Netherlands in 1995, mainly through one heavily infected seed‐tuber line. The bacterium was found in most infested countries in surface water and in the weed Solanum dulcamara growing along waterways. In some countries, tomato was also found to be infected. The history of the so‐called‘low‐temperature’race 3, adapted to more temperate climates (also occurring at higher altitudes in the tropics) is described, together with details on its host range and geographical distribution. Possible origins of the disease in western Europe are discussed, including introduction through import of infected early ware or industrial potatoes from some countries in the Mediterranean area, where the disease is established. The brown rot bacterium has many similarities concerning its biology and epidemiology with some other infectious diseases, e.g. with cholera, and useful comparisons can be made for control strategies. A detailed account on the epidemiology of P. solanacearum and possible prevention and control strategies is presented. These strategies are: (1) responsibility for prevention and control is for the country where the disease occurs; (2) countries where the disease occurs should report outbreaks as soon as possible; (3) early and sure detection and diagnosis of the pathogen are the core of the system; (4) adequate prevention and control measures should be taken after an outbreak; (5) production of healthy seed tubers should be guaranteed and surveys and (laboratory) checks for (latent) infections performed; (6) education of scientific personnel and the public (farmers, traders, advisory service, etc.) is essential. It is foreseen that hygienic measures and avoidance of surface water for irrigation will be key factors in successful control of the disease.