Potato: the Pectobacterium Empire strikes back

Blackleg disease on potato is caused by several pectinolytic bacterial species and subspecies. Until 2012, most of the blackleg-diseased plants observed in Switzerland were infected with species belonging to the genus Dickeya. During 2013, two other species were found to be responsible for several blackleg infections: Pectobacterium wasabiae and Pectobacterium carotovorum subsp. brasiliense. The former is well distributed in Europe wherefore its presence in Switzerland was not a surprise. The latter had not been identified in Europe before 2013, but isolates from 1988 and 1999 were found subsequently in the bacterial collection of Agroscope. The strain P. c. subsp. brasiliense already caused damages in 2014 and was alone responsible for 80 % of the blackleg-diseased plants sampled and analysed in the laboratory. Moreover, atypical blackleg symptoms were observed during the growing season 2014, which could lead to disease misidentification during the field controls for certification.