Top wilt/ blackleg/ soft rot – Dickeya spp.
The genus Dickeya was previously known as Erwinia chrysanthemi. There are two significant potato pathogens within this genus currently affecting Europe; Dickeya dianthicola and ‘Dickeya solani’. D. dianthicola has never been found on Scottish potatoes. ‘D. solani’ emerged in Europe around 2005-2006. It is highly aggressive on potato, causing rapid wilting and blackleg-like symptoms across wide environmental conditions.
Preliminary research indicates that ‘D. solani’ may be significantly more aggressive than D. dianthicola and Pectobacterium atrosepticum. The new species appears to be able to rapidly induce blackleg symptoms and also to rot developing progeny tubers, even when inoculum levels are low. Aggressiveness of the new Dickeya pathogen appears to further increase at higher temperatures so there are implications for increased importance of this pathogen in response to global warming. As yet, there is little substantiated practical information on the biology of this strain in relation to its host range, its ability to survive, establish and spread in the environment or its behaviour on stored potato tubers.
Information on a range of measures to protect Scotland's ware growers against Dickeya, and a range of threats, can be found in the Defending your potato crop against disease leaflet.
SASA