First report of ‘Candidatus Arsenophonus phytopathogenicus’ on potato in Switzerland
In Switzerland, ‘Candidatus Arsenophonus phytopathogenicus’ (formerly EPPO Alert List) was first reported in on sugar beet (Beta vulgaris) in 2017 in the western part of the country. Annual surveys conducted in 2023 and 2024 also detected it in eastern Switzerland.
In July 2023, potato plants (Solanum tuberosum) infested with Pentastiridius leporinus (Hemiptera: Cixiidae) showing leaf and stem desiccation and rubbery tubers were observed in fields in the cantons of Bern, Fribourg and Vaud in western Switzerland. These fields were located in areas experiencing outbreaks of ‘Syndrome des basses richesses’ on sugar beet (Beta vulgaris). Molecular tests confirmed the presence of ‘Ca. Arsenophonus phytopathogenicus’ in diseased tubers and in P. leporinus. The authors caution that the reported symptoms may appear more severe due to a drought earlier in 2023 which affected the general health status of potato crops.
In certain potato varieties, the infection of tubers by ‘Ca. Arsenophonus phytopathogenicus’ seems to induce the browning of the flesh upon frying, raising strong concerns for varieties marketed for chip production.
Sources
Mahillon M, Bussereau F, Dubuis N, Brodard J, Debonneville C, Schumpp O (2025) First detection of Arsenophonus in potato crop in Switzerland: a threat for the processing industry?. Potato Research (early view). https://doi.org/10.1007/s11540-024-09840-y