First report of blackleg and soft rot of potato caused by Pectobacterium carotovorum subsp. brasiliensis in New Zealand

Abstract

Blackleg and stem rot of potato occur sporadically in New Zealand, causing economic damage under optimal temperature and humidity conditions for disease development. Both Pectobacterium atrosepticum (Pba) and P. carotovorum subsp. carotovorum (Pcc) have previously been isolated from potato tubers with soft rot symptoms in New Zealand (Crowhurst & Wright, 1998) whereas only Pba has been shown to cause blackleg. A collection of 89 enterobacteria were recently isolated from potato tubers from commercial crops in the Auckland, Waikato, Manawatu-Wanganui and Canterbury regions of New Zealand. The majority were initially assigned as Pcc by their growth at 37°C, carbon utilisation profiles and restriction fragment length polymorphisms (Pitman et al., 2008). These isolates were mostly unable to cause blackleg symptoms, although several were shown to be highly aggressive upon stem infection.