New haplotypes of Synchytrium endobioticum in the Netherlands
In 2025 two new pathotypes of Synchytrium endobioticum (potato wart disease, EPPO A2 List) were detected in the Netherlands on starch potato (Solanum tuberosum). One was found in an infested field in autumn 2023. The pathotype P 42(Erica) was confirmed in April 2025 using the Spieckermann method on a range of differentials that included an additional cultivar (Seresta). Mid-May 2025 another new pathotype was suspected for which the pathotype determination is to be confirmed. Wart spores of two earlier findings in 2022 were used for infection and caused wart formation on the cultivar Belita, which was so far known for its resistance against all known pathotypes of wart disease in the Netherlands.
The NPPO considers that the rapid development of these new pathotypes in addition to the finding of P38-Nevşehir in 2021 (EPPO RS 2021/200) in the Netherlands is worrying as no or very limited resistant varieties of potato are available for growers. To date, these new pathotypes have only been recorded in starch potato production. Awareness has been raised amongst growers and packing stations to pay close attention to prevention and report any suspicion of wart disease. An adjustment of the measures in the starch potato production area is being considered.
The pest status of Synchytrium endobioticum in the Netherlands is officially declared as: Present, under eradication, only in demarcated areas.
Sources
NPPO of the Netherlands (2026-02).