EuroBlight final data release, 2025

EuroBlight announce the final results of 2025 monitoring – despite the low blight pressure 2025 season over 1700 samples from 27 countries across Europe were genotyped.

July 2026, Jens Grønbech Hansen, Geert Kessel and David Cooke 

As presented at the 21st EuroBlight workshop in Spain, here we formally release the population analysis on the late blight samples collected from the 2025 European 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 256 in 2025.  This bottleneck in the populations may skew findings in some areas in favour of samples from field trial sites or other sources such as volunteer potatoes.  For example, in Britain more than half of the sampled outbreaks were collected from volunteer potatoes from September onwards. 

A summary of the results:

  • The P. infestans population in Europe in 2025 remained dominated by the EU36 genotype which comprised 31% of samples. The decline in the EU43 genotype has stabilised with the very slight increase in frequency due primarily to an increased in French crops from 10 to 24% of samples. The range of EU43 also expanded to include England, Switzerland, Latvia and Estonia in 2025. The EU46 genotype increased slightly from 4% to 7% of samples in 2025 and expanded its range to 14 countries (see below). In general, EU36 is however dominating in west and central Europe and isolates from the group “Other” comprising 36% 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 than in the past.
  • The overall frequency of EU43 decreased from 23% in 2023 to 9% in 2024 with a slight increase to 10% of all samples in 2025. Variation was marked among countries; for example, 15% (n = 99) in 2025 in the NL, 18% (n = 109) in DE and 10% (n = 48) in BE. In Denmark the proportion of EU43 dropped again to 3% (n=156). As mentioned above, a notable increase was observed in FR with EU43 more than doubling in frequency from 10 to 24% (n = 362) of the samples taken in 2025.  More information on EU43 and EU46 and fungicide resistance may be found in these recent papers: “New Mechanisms of Resistance to CAA and OSBPI Fungicides in Phytophthora infestans” and “Characterization of CAA-, OSBPI- and double resistant field isolates of Phytophthora infestans and their impact on late blight control in potatoes”.
  • The frequency of EU46 sampled across European crops increased again from 4% in 2024 to 7% in 2025 and there was considerable regional variation. For example, it decreased in NL to 1% (n = 99) and was not sampled in DK (n = 156). Conversely it was stable in DE at 18% (n = 109) increased in BE to 4% (n = 48) and in GB to 14% (n = 377) with the rest of the increase due to a range expansion with EU46 found for the first time in 2025 in samples from England, Norway, Sweden, Latvia, France, Austria and Switzerland.
  • EU36 is an aggressive triploid genotype which has come to dominate outbreaks across many parts of Europe since its first appearance in 2013. 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 31% in 2025. Again, there was considerable regional variation with 44, 65 and 77% of the 2025 samples in NL, FR and BE respectively being EU36 yet it was only rarely sampled in DK or Baltic countries and never in NO, SE or FI. It is reported that some isolates of EU36 can defeat sources of single and double R-gene blight resistance and also that mutants with OSBPI fungicide resistance are locally prevalent. More phenotypic testing is, however required to better understand its success.  
  • Considering other clones of note:
    • EU41 increased slightly from 2% in 2024 to 4% in 2025; down from its highest proportion at 6% in 2020. This clone was mostly found in NO, DK and Scotland (SC) where it comprised 19% of the population (n = 167) in 2025. It was also found in northern DE and a single sample in Malta.
    • EU45 has steadily expanded its range 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 2% 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 highs of 14% in 2017 and 2018. Changing use of fluazinam has driven this reduction and extended the life of this active ingredient.
    • EU47 clone with novel virulence against valuable sources of blight resistance was newly named in 2024 but only sampled in CH in 2025 and comprised less than 1% of the sampled population.  It was preferentially sampled on cultivars with specific blight resistance defined in Group C of the boakkerbouw Wageningen Task Force.
  • At 36%, the proportion of the highly diverse ‘Other’ population was more than double that of 15% sampled in 2024.  This very likely represents a generally lower proportion of 2025 samples from western regions of Europe that are dominated by clonal populations. France was an exception to this with almost 340 samples of which 99% were clonal lineages in 2025. However, in DE a marked increase from 18 to 46% from 2024 to 2025 was observed. In Baltic and Nordic countries the proportion at around 85% of the samples in 2025 was similar to that in 2024. 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. 

Genotype maps and charts are available here:

Pathogen Dashboard

A new Pathogen–Host Dashboard has been developed to explore the interactions between Phytophthora infestans SSR genotypes and potato cultivars. A detailed user guide will be available soon, but in the meantime we encourage you to explore the dashboard yourself.

To get started, select a country and begin exploring the data. The dashboard is fully interactive: whenever you make a selection in one panel, most of the other charts and tables update automatically to reflect your choice.

Try clicking on a bar in a chart or a segment of a pie chart to filter the data further and see how the other visualisations respond. Exploring the dashboard in this way is the best way to become familiar with its functionality.

 For 2026, please be careful to report the cultivar name as well during sampling.

Acknowledgements

We thank all 39 partners and sponsors that have contributed with samples and data in 2025. A total of 71 organisations have contributed samples since 2013. We acknowledge James Lynott and the team at Hutton who have processed the samples throughout the season, INRAE for French sample genotyping and Aarhus University for the data management and visualisation of the results.

2025 sponsors (listed alphabetically)

Commercial: ADAMA, Agriana, BASF, Bayer, Certis Belchim, Corteva, Cultus, Eurofins, Fight Against Blight, HLB, HZPC, Norika, Oxford Agricultural Trials, Pepsico, SA Consulting, Saka, Solynta, Staphyt, Syngenta, SynTech. 

Academic and research: Aarhus University, Agroscope, ARVALIS, CRAW, Estonian University of Life Sciences, INRAE, JKI, LfL, LWK, NIBIO, NLR, Petla (PJI), SRUC, SLU, TEAGASC, Hutton, University of Fribourg, University of Vigo, Wageningen University

Contacts

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Revideret 27.09.2022
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