First report of Peronospora aquilegiicola, the downy mildew of columbines in Germany
The NPPO of Germany recently informed the EPPO Secretariat of the first occurrence of Peronospora aquilegiicola on its territory. In Spring 2020, a private garden owner submitted a plant sample of diseased Aquilegia sp. to the plant protection service of Lower Saxony. The owner had observed heavy symptoms of downy mildew on Aquilegia sp. in 2019 which recurred in 2020. The pathogen species was identified via morphological and molecular methods. About 400 plants on an area of 200 m2 were affected. The plants showed varying degrees of symptoms ranging from chlorotic necrosis and slight twisted growth to the death of whole plants. A preliminary PRA was performed, which concluded that P. aquilegiicola may fulfil the criteria of a quarantine pest. Officially measures were taken to eradicate the pest. As the plants were not planted in the garden by the owner but appeared spontaneously, the source of the outbreak is unknown.
The pest status of Peronospora aquilegiicola in Germany is officially declared as: Present, under eradication.
EPPO note: Aquilegia spp. includes both native and ornamental plants in the EPPO region. Peronospora aquilegiicola was first reported in the United Kingdom in 2013. As it was considered established and widespread in England and Wales, no statutory action was taken. The report in Germany is the first for continental Europe. P. aquilegiicola can be spread via the movement of infected seed or host plants for planting. A recent article showed that P. aquilegiicola is an indigenous species in northeast Asia and it was first found on Semiaquilegia adoxoides in China. Semiaquilegia is an Asian plant genus closely related to Aquilegia. The genetic similarity of P. aquilegiicola collections from South Korea and the United Kingdom suggests that this pathogen has been quite recently introduced to the United Kingdom, presumably by trade with infected plants or seeds from East Asia. Finally, several risk assessments have been recently conducted in the EPPO region and are available in the EPPO PRA Platform: https://pra.eppo.int/organism/PEROAQ
Sources
NPPO of Germany (2020-06).
Denton GJ, Beal EJ, Kilty A, Denton JO, Choi YJ, Thines M (2015) Characterisation and risk assessment of the emerging Peronospora disease on Aquilegia. Mycological Progress 14, 69. https://doi.org/10.1007/s11557-015-1092-5
JKI (2020) Express – PRA zu Peronospora aquilegiicola. Avalaible at https://pflanzengesundheit.julius-kuehn.de/schaedlinge---risikoanalysen.html
Thines M, Denton GJ, Beal EJ, Kilty A, Denton JO, Shin HD & Choi YJ (2019). Peronospora aquilegiicola sp. nov., the downy mildew affecting columbines in the UK is an invasive species from East Asia. European Journal of Plant Pathology https://doi.org/10.1007/s10658-019-01787-y.
Tuffen M (2016) Rapid Pest Risk Analysis (PRA) for: Peronospora sp. on Aquilegia. Department for Environment Food & Rural Affairs, York, UK.