Late blight discovery


04 March 2022
New strain raises questions and highlights the value of monitoring

THE first case of the 41_A2 late blight genotype that emerged in Denmark in 2013 was detected in a crop of Maris Piper grown in Fife last August. The news was described as evidence of the value that genotype testing until now funded by AHDB Potatoes provides to growers.


Speaking at the Scottish Agronomy potato conference held online on 2 February, Dr David Cooke, research lead in Cell and Molecular Sciences at the James Hutton Institute and co-ordinator for the EuroBlight potato late blight monitoring project, explained that the genotype was detected during routine sample analysis.


There is no indication of its source, but human activity would be the likely cause given that regulations in Scotland mean only home-grown seed can be planted.

“The alternative windborne route would involve about a 700-kilometre journey from mainland Europe against the prevailing airflow,” David said.


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Eric Anderson, Scottish Agronomy Senior Agronomist, agreed that the distance to known source of infection in Scandinavia or the Netherlands meant airborne spread was highly unlikely. “It’s almost certainly human interaction of some kind but we should not discount the possibility that it spread from a tomato plant to a potato crop,” Eric said.


The 2021 season was another atypical year for late blight (Phytophthora infestans) with the cold spring delaying the first cases of disease. As a result outbreaks in Scotland were later than average and in south-east England, they appeared to be highly localised.


To read our fuller feature, see the March issue of Potato Review. You can subscribe here.


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