EuroBlight early data release, 2025
EuroBlight releases the first set of genotype results, 2025 - totalling approximately 1250 results from all over Europe. More data to come.
15 December 2025, Jens Grønbech Hansen, Geert Kessel and David Cooke
Read the news story in pdf
EuroBlight just released the first set of genotyping results – despite the low blight pressure 2025 season over 1200 samples from across Europe were genotyped to date.
Given ongoing concern from the potato industry on the impact of the EU43 and EU46 lineages of P. infestans, the EuroBlight monitoring team here releases an early set of results on the status samples collected from the 2025 potato crop. A general trend this year was that warm, dry weather across many potato growing regions, in particular from March to July, reduced primary inoculum levels and thus disease pressure across much of the season. For example, in the Netherlands, Germany and Belgium there were over 1000 samples collected in 2024 but only 166 in 2025. This bottleneck in the populations may skew the results in favour of samples from field trial sites or other sources. For example, in Britain more than half of the sampled outbreaks were from volunteer potato plants from September onwards. The data was released to the public side of the EuroBlight database on the 11 December.
A summary of the results to date:
- The P. infestans population in Europe in 2025 remained dominated by the EU36 genotype which comprised around one third of samples. The decline in the EU43 genotype has stabilised with an overall slight uptick in frequency but a notable increased in French crops from 10 to 25% of samples. Its range also expanded to include Switzerland and Latvia in 2025. The EU46 genotype increased from 4% to 7% of samples in 2025 and expanded its range to 12 countries with new findings in England, Norway, Sweden, Latvia and France. In general, EU36 is however dominating in west and central Europe and isolates from the group “Other” comprising 33% are dominating in the northeast of Europe. The relatively new clones, EU43 and EU46 with reported resistance to some active ingredients have been broadly suppressed through modified approaches to fungicide use with more mixing and alternation of FRAC active ingredient groups.
- The overall frequency of EU43 had decreased from 23% in 2023 to 9% in 2024 with a slight increase to 12% of all early samples in 2025. Variation was marked among countries; for example, 20% (n = 69) in 2025 in the NL, 12% (n = 58) in DE and 13% (n = 39) in BE. In Denmark the proportion of EU43 dropped again to 4% (n=103). As mentioned above, a notable increase was observed in FR with EU43 more than doubling in frequency from 10 to 25% (n = 345) of the samples taken in 2025. More information on EU43 and EU46 and fungicide resistance may be found in this recent paper: “New Mechanisms of Resistance to CAA and OSBPI Fungicides in Phytophthora infestans”
- Although the frequency of EU46 sampled across European crops increased again from 4% in 2024 to 7% in 2025 there was considerable regional variation. For example, it decreased in NL to 1% (n = 69), in DE to 7% (n = 58) and was not sampled in DK (n = 103). Conversely it increased in BE to 5% (n = 39) and in GB to 20% (n = 278) with the rest of the increase due to a range expansion to England, Norway, Sweden, Latvia and France in 2025.
- EU36 is an aggressive genotype and dominant across many parts of Europe. At the European level, the progressive increase in this clone was checked in 2025 with a fall in sampling frequency from 52% in 2024 to 34% in 2025. Again, there was considerable regional variation with 43%, 64% and 74% of the samples in NL, FR and BE respectively being EU36 but, it was not sampled in the Nordic countries, except one isolate found in DK. Additional phenotypic testing is required to better understand its success. It is for example, reported that isolates in the EU36 group can defeat sources of single and double R-gene blight resistance.
- Considering other clones of note:
- EU41 increased slightly from 2% in 2024 to almost 5% in 2025. This clone is localised to NO and DK where it comprised 2-5% of the population and in Scotland where it comprised 25% of the population (n = 113 ) in 2025. In DK, all 10 isolates of EU41 on the same trial location.
- EU45 had been steadily expanding after its initial sampling in Germany in 2019. It had spread to comprise 4% of the samples in 2024 but in 2025 this fell to 1% with an expansion of range to eight countries that now includes Poland.
- EU37 clone that has demonstrated resistance to fluazinam once again remains at a low incidence at 1% of the samples in 2025 compared to its high of 14% in 2017 and 2018.
- EU47 clone with novel virulence against R8 and R9 resistance genes was newly reported in 2024 but not sampled in 2025. This may reflect the bottleneck in the population due to the warm dry conditions across many potato growing regions of Europe in 2025.
- At 33%, the proportion of the highly diverse ‘Other’ population was double that of 15% sampled in 2024. This very likely represents a higher proportion of 2025 samples from northern and eastern regions that are not dominated by clonal populations of P. infestans. For example, in DK and NO 85% of the samples from 2025 were ‘Other’. Data from many years show a consistent incidence of highly localised and ephemeral multi-locus genotypes that do not reach the threshold for being named as clones. This is consistent with oospore inoculum in the soil that germinates and causes local infection.
Fig 1. Genotype frequency map, Europe 2025
Fig 2. Genotype frequency chart, Europe 2024
Genotype maps and charts are available here:
https://agro.au.dk/forskning/internationale-platforme/euroblight/pathogen-monitoring/genotype-map
We thank all partners and sponsors that have contributed with samples and data this year. A full list will be provided in the later data release. We would also like to acknowledge James Lynott and the rest of the team at Hutton who have worked hard to process the samples throughout the season, and AU for doing the data management and visualisation of the results.
Contacts
- Jens G. Hansen & Poul Lassen, Aarhus University. Contact: jensg.hansen@agro.au.dk
- David Cooke & Alison Lees: James Hutton Institute, Dundee. Contact: david.cooke@hutton.ac.uk
- Geert Kessel, Wageningen University and Research Centre. Contact: geert.kessel@wur.nl
- Didier Andrivon & Romain Mabon, INRAE. Contact: Didier.Andrivon@inrae.fr
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