First report of Plasmopara obducens in Norway
In August 2008, diseased Impatiens walleriana plants were received from a private garden in Oslo (Norway) for diagnosis. The pathogen was identified (morphology, PCR) as Plasmopara obducens (formerly EPPO Alert List). Severe disease outbreaks were later observed in 2008 on I. walleriana cv. ‘Xtreme Red’ in public parks in Oslo and Bergen (South-Western Norway). In 2009, the disease was again found outdoors at several places in South-Eastern Norway (also on cv. ‘Xtreme Red’), and in 2 glasshouses on I. walleriana cv. ‘Silhouette’ which had been grown from imported cuttings. It is noted that in the past, P. obducens had been observed outdoors on I. noli-tangere, a native plant in Norway. However, it is not known whether the pathogen observed on I. walleriana is exactly the same as the one which was previously found in native Impatiens species in Norway.
Toppe B, Brurberg MB, Stensvand A, Herrero ML (2010) First report of Plasmopara obducens (downy mildew) on Impatiens walleriana in Norway. New Disease Reports Volume 20 (2009-09 to 2010-01). http://www.bspp.org.uk/publications/new-disease-reports/ndr.php?id=020033