Blackleg in potatoes – Rapid haulm destruction key to blackleg control

Over the past few seasons, blackleg has been the thorn in the side of Scottish seed producers, who otherwise are producing seed of the highest quality. In recent years, levels of blackleg have mysteriously begun to increase, with the disease now the number one reason for down-grading or failure of seed stocks.The inevitable question is ‘why is this happening?’, says Prof Ian Toth, research theme leader at the James Hutton Institute. To try and understand the issue, AHDB Potatoes and SASA jointly funded a three-year project to identify the routes of blackleg contamination. The point where levels of the bacteria responsible for blackleg, Pectobacterium atrosepticum (Pba), reached their highest levels coincided with haulm desiccation, which indicated that the method of haulm destruction may have a critical bearing on the potential levels of blackleg infection, he says. The discovery that blackleg can develop through the contamination of roots and doesn’t require a contaminated seed tuber means that even very high quality seed is at risk from picking up infection during the same season. More