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2025: Screening trial for potato varieties and clones

The SESUR potato variety trial in Sevilla is a fixed part of the testing programme of several European potato breeders and serves to capture, under real conditions, how new breeding lines and established varieties behave under the intensive growing conditions of southern Spain and the Mediterranean region. The 2026 season represents an exceptional testing ground: unusual weather has once again turned the trial into a stress test for varieties and seed – with results that are of particular interest to breeders and the management of breeding companies, and that could not be observed in this form in Central and Northern Europe.
Weather Conditions and Growing Conditions
The season got off to an atypical start: continuous rainfall persisted until the end of February, making field cultivation and planting impossible. As a result, actual planting took place around three months later than in a normal year.

After planting, the situation reversed: a phase of extremely vigorous growing weather followed, with almost no disease pressure. Due to the late planting, the growing cycle was shortened this year to around 90 days. An extension was not considered, given the likelihood of extreme temperatures from mid-June onwards. As a result, at the time of the first harvesting some of the stands were not yet fully desiccated and were still partly in flower; skin set was not yet fully developed at this point.

● Planting delayed by around three months due to persistent winter rainfall
● Extremely vigorous growth phase with very low disease pressure
● Shortened cycle of approx. 90 days
● Desiccation occurred in part of the stands while still in the flowering phase
● Skin set not yet fully developed at the first harvesting dates
● Visible differences between replicates, even though the trial field shows no discernible differences in soil structure

Seed Quality
The trial seed was already prepared at the end of December 2025. Due to the persistent rainfall, planting was delayed by almost three months, causing the tubers to sprout extremely during this time while still in their crates. To document the germination status of the seed in a traceable way, it was recorded photographically for each plot.

Key Trial Data

26.12.2025 Preparation of trial seed
05.03.2026 Trial Planting
27.05.–11.06.2026 Harvesting
28.05.2026 Desiccation of the Stands (Burning Plants)
Growing cycle approx. 90 days

Summary and Implications for Evaluation
Once again this year, the trial was a genuinely exceptional one: late planting, heavily pre-sprouted seed and extremely vigorous weather meant that, at the time of harvesting, the growing cycle in part of the stands was not yet fully complete – desiccation occurred mid-cycle, in some cases still during flowering.
The results of this trial are meaningful, but can only be interpreted appropriately if they are consistently viewed in light of the conditions described above. Precisely because the 2026 season pushed the varieties under test to their limits, it provides valuable additional insight into robustness, adaptability and desiccation behaviour under real, non-standardised stress conditions – information that would scarcely be visible in this clarity under average growing conditions.

2025-04-24: SESUR Fieldday and International PotatoVariety Demonstration in Seville

Some impressions from the Fieldday

2024: Screening trial for potato varieties and clones

2023: Screening trial for potato varieties and clones

2023 spring: sustainable cultivation of carrot with BioAgenaSol and Fla-One (without pesticides and chemical fertilisers)

please click on the image to download the full presentation (Spanish)

2022 spring: Internal breeders screening trial in Seville

2021 spring: Variety and screening trial in Seville

2021-05-07: Fieldday and Variety Presentation

2020-10-13: Soil Analysis with Greenfield

2020 spring: Variety and screening trial in Seville

2019-07-17: sustainable carrot production without mineral N in Cadiz

click on the image to download full presentation

please click on the image to download the full presentation (Spanish)

2019-06-23-28: Participation and sponsoring of ISMOM 2019 Seville

8th International Symposium on Interactions of Soil Minerals with Organic Components and Microorganisms (www.ismom2019.org)

2019-05: Test of "Keiler" harvester in Seville

2019 Spring: Internal breeders screening trial in Seville

2018 Spring: Internal breeders screening trial in Seville

2017-04-28: Fieldday and variety demonstration in Seville

More than 200 varieties and clones from 20 European breeding and seed distribution companies grown at the one site under the same conditions will be exhibited to professional visitors.

2015-04-17: Fieldday and variety demonstration in Seville

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Over 100 varieties from the following 20 breeders have been demonstrated

Agroplant (Holland)		Bavaria Saat (Germany)
CullenAllen (UK-Irland)		Pepsur Marketing (UK-Spain)
Danespo (Danmark)		Den Hartigh (Holland)
Europlant (Germany)		Euroseeds (Holland)
Germicopa (France)		Gopex (France)
Greenvale (UK-England)		Interseed (Germany)
KWS (Germany)		Meijer (Holland)
Norika (Germany)		Semagri (Holland)
Plantera (Holland)		Van Rijn (France)
Solana (Germany)