First report of ‘Candidatus Arsenophonus phytopathogenicus’ on onion in Germany
In January 2024, rotting symptoms were observed on onions (Allium cepa), that were harvested in a healthy state in September 2023 in Hessen, south-west Germany. The onions had been harvested from a field located in a region severely affected by ‘syndrome des basses richesses’ (formerly EPPO Alert List). ‘Syndrome des basses richesses’ is a disease of sugar beet (Beta vulgaris) mainly associated with a γ-proteobacterium ‘Ca. Arsenophonus phytopathogenicus’ transmitted by the polyphagous planthopper Pentastiridius leporinus (Hemiptera: Cixiidae), which is abundant in the region where the onions were grown. Molecular testing confirmed the presence of ‘Ca. Arsenophonus phytopathogenicus’ in symptomatic material. This suggests that onion could be a host of ‘Ca. Arsenophonus phytopathogenicus’, however more tests are needed to confirm the host status of A. cepa. It may be noted that potato had recently been recorded as a new host of this bacteria in Germany (EPPO RS 2023/029).
Sources
Therhaag E, Ulrich R, Gross J and Schneider B (2024) Onion (Allium cepa) as a new host for ‘Candidatus Arsenophonus phytopathogenicus’ in Germany. Plant Disease 108 (9), 2914. https://doi.org/10.1094/PDIS-03-24-0526-PDN