Analysis of the risk of brown rot to the high-grade seed potato production in Scotland

摘要

Potato brown rot is caused by the quarantine bacterium Ralstonia solanacearum. Outbreaks in Europe have been associated with the irrigation of potato crops with contaminated river water. Although R. solanacearum was detected in one Scottish river in the past, the bacterium has never been found in Scottish potatoes. After three years of eradication and monitoring, Scotland is now free of the bacterium. This paper assesses the risk of spread of R. solanacearum via surface water and of the occurrence ofbrown rot in seed crops under Scottish conditions. At least 50 Scottish river systems flowing through potato growing areas may be at risk from contamination with R. solanacearum. Long-term survival of the bacterium in Scottish waters is unlikely withoutthe presence of the wild host Solanum dulcamara. This plant is not widespread in Scotland and has so far been found in only 6 out of 48 river systems surveyed. Ten of the 50 river systems potentially at risk from contamination have been used for irrigation in the past two years. Although the acreage of seed crops irrigated from these waterways is relatively small, prevention of infection is important to avoid the occurrence and spread of brown rot in Scotland, especially since R. solanacearum biovar 2,race 3 is able to infect Scottish potato varieties and cause disease under Scottish conditions. Testing of Scottish waterways for the presence of the brown rot pathogen continues to prevent the contamination of fields and ensure the good health of Scottish seed.