A new potato blight strain, resistant to some of the main fungicides for blight control in Ireland such as Revus and possibly Zorvec, is a major concern for the sector here in Ireland.

Two cases of the strain known as EU43 were found in Ireland in 2023.

Speaking at the Teagasc potato blight workshop in Teagasc Ashtown on Tuesday 26 March, Geert Kessel from Wageningen University in the Netherlands explained that the strain was first found in Denmark in 2018.

It was found in the Netherlands in 2021 and took up 2% of the population that year. By 2022, it took up 43% of the blight population.


If correct fungicide programmes are not followed, such as mixing products and avoiding applying products numerous times in a row, then this can help to increase the prominence of the strain, known as a process called selection.

While some farmers have potatoes from 2023 still to dig and wait for weather to plant in 2024, Teagasc researcher Steven Kildea was keen to get the message out there ahead of the season that this strain is present.

He noted that resistant strains found in Europe generally turn up in Ireland two to three years later. He wants farmers to send leaf samples to Teagasc during the season so that they can be genotyped to identify the strain of blight present.

“It is in the country. It’s something that we need to be aware of,” he said.

Pest management

Good integrated pest management still needs to be adhered to to reduce blight risk, such as rotation length and controlling potato volunteers in other crops, as well as disease prevention rather than cure and mixing and alternating fungicides.

UK researcher David Cooke noted that strategies to reduce resistance risk can work.

For example, another active ingredient fluazinam (found in Shirlan) was found to have poor control of resistant gene EU37, but it was controlling other blight strains.