This season’s Scottish growing crop survey has found no signs of Dickeya, marking the third consecutive season that Scotland has been free of the disease.
Dickeya species, particularly Dickeya solani, is a major pathogen of potato in many European countries and Israel, says Gerry Saddler, head of diagnostics and analytical services at Science and Advice for Scottish Agriculture (SASA).
It is highly aggressive on potato crops, causing rapid wilting and blackleg-like symptoms across wide environmental conditions.
It can prove devastating, with the disease resulting in production losses in Dutch seed potatoes of €25m in 2007, due to downgrading and rejection of more than 20% of stocks during certification.
Dr Saddler adds that it has been found previously in a small number of ware crops grown in Scotland during 2009 and 2010, all of which were produced from non-Scottish-origin seed. It has never been found in Scottish seed potatoes, nor potatoes grown in Scotland from Scottish-origin seed.
In this year’s testing, 671 samples were tested from field-grown potatoes showing signs of blackleg and the pathogen was not found.
It is particularly noteworthy that no positive findings were made in 2013, as the prevailing warm and dry conditions during the growing season favoured the pathogen, says Dr Saddler.
“The lack of any positive findings this year puts to rest a possible theory that the pathogen had already established itself in Scotland and was lying dormant during the unfavourable summers of 2011 and 2012.
“These results reinforce the view that seed is the source of the infection and serve as a timely reminder that purchasing Scottish-origin seed potatoes is an effective means of maintaining our freedom from Dickeya infection,” says Dr Saddler.