Investigation and control of potato brown rot in Germany, especially in Bayern¹

Abstract

Ralstonia solanacearum has been found in Dutch potato production since 1995. For this reason, comprehensive laboratory tests on seed‐ and ware‐potato production have been carried out in Germany. The amount of tested potato lots has increased fivefold. In 1997, 10678 tests were carried out on seed potatoes and 2351 tests on ware potatoes respectively. In 1996, R. solanacearum was found in five lots in Bayern and in one lot in Brandenburg, and in 1997 only in two ware‐potato lots in Bayern. A thorough analysis was carried out to find the source of infection, but it was not possible to identify it clearly. The measures taken were based on the draft Control Directive for brown rot, which will soon be adopted by the Council of the European Union, and were very restrictive for the affected farms. Monitoring of a potato‐processing enterprise that had processed an infected lot without permit in 1996 established that R. solanacearum was present in wastewater. This paper discusses the measures taken in Bayern and the risks of further introduction.

Spatial Stochastic Simulation Offers Potential as a Quantitative Method for Pest Risk Analysis

“…Solanum dulcamara is particularly susceptible to infection caused by the pathogen R. solanacearum , and the bacterium is known to be naturally disseminated via surface water, especially in watercourses inhabited by S. dulcamara . ( 9 , 35 , 37 ) Potato tubers ( Solanum tuberosum ) are also known to be effective as dispersal units of this pathogen. ( 35 ) R. solanacearum is not known to be dependent on any vectors in its life cycle other than its host's.…”

“…Regarding the initial step, release of R. solanacearum into the environment could occur in many ways, e.g., via infected potato tubers ( 35 ) or via infested potato peeling wastewater from potato processing plants ( 9 , 37 ) or private households. Second, the timing of releases will be important because the climate of the study area, which influences survival, varies during the year.…”

“…( 35 ) The bacterium is known to be able to disseminate from infected host plants and via water to infect new host plants. ( 9 , 35 , 37 ) Since the dissemination of this organism in water occurs by passive transport, it will be disseminated in the drainage direction. Dissemination potential is the main reason why R. solanacearum is a hazardous pest, so the model for simulating pest introductions should describe this phenomenon carefully.…”