In May 2011, young Impatiens walleriana Hook. f. plants showing downy mildew symptoms were collected from a greenhouse (Kecskemét, Hungary). The upper surface of affected leaves turned yellow and white fungal-like growth was observed on the underside. Diseased plants wilted and rapidly collapsed, resulting in losses of nearly 100%. Downy mildew of impatiens can be caused by two pathogens, Plasmopara obducens or Plasmopara constantinescui (syn: Bremiella sphaerosperma), which can be distinguished by the symptoms and by morphology of sporangiophores and sporangia. For molecular identification the 5′-end of the large subunit of ribosomal RNA gene was amplified by PCR using NL1 and NL4 primers and cloned and sequenced. The nucleotide sequence of the Hungarian isolate showed highest identity (99.72%) with two isolates of Plasmopara obducens from the United Kingdom and Serbia. On the basis of the symptoms, molecular and morphological characters, the pathogen was identified as P. obducens. The appearance of the pathogen in Hungary seriously endangers the production of I. walleriana, which is a popular ornamental in gardens and city parks. The chemical plant protection is not effective against the pathogen, by the occurrence of the first symptoms the diseased plants should be removed from the plantlet and must be destroyed.
Anon. (2005): Addition of Plasmopara obducens to the EPPO Alert List. EPPO Reporting Service NO. 7 Paris, 2005-07-01. 2005/108.
Bulajić, A., Vučurović, A., Stanković, I., Ristić, D., Jović, J., Stojković, B. & Krstić, B. (2011): First report of Plasmopara obducens on Impatiens walleriana in Serbia. Plant Dis., 95, 491.
Krstić B., 'First report of Plasmopara obducens on Impatiens walleriana in Serbia' (2011) 95Plant Dis.: 491-.
Krstić B.First report of Plasmopara obducens on Impatiens walleriana in SerbiaPlant Dis.201195491)| false
Farr, D.F. & Rossman, A.Y. (2011): Fungal databases, systematic mycology and microbiology laboratories. United States Department of Agriculture — Agricultural Research Service. Retrieved October 11. 2011.
Glits, M. (2000): Oospórás gombák. (Ospores fungi.) -in: Glits, M. & Folk, Gy.Kertészeti növénykórtan. Horticulturae plant pathology.) Mezőgazda Kiadó. Budapest, pp. 86–87.
Glits M., '', in Kertészeti növénykórtan, (2000) -.
Glits M.Kertészeti növénykórtan2000)| false
Göker, M., Voglmayr, H., Riethmüller, A., Weiss, M. & Oberwinkler, F. (2003): Taxonomic aspects of Peronosporaceae inferred from Bayesian molecular phylogenetics. Can. J. Bot., 81, 672–683.
Oberwinkler F., 'Taxonomic aspects of Peronosporaceae inferred from Bayesian molecular phylogenetics' (2003) 81Can. J. Bot.: 672-683.
Oberwinkler F.Taxonomic aspects of Peronosporaceae inferred from Bayesian molecular phylogeneticsCan. J. Bot.200381672683)| false
Lane, C.R., Beales, P.A., O’Neill, T.M., McPherson, G.M., Finlay, A.R., David, J., Constantinescu, O. & Henricot, B. (2005): First report of Impatiens downy mildew (Plasmopara obducens) in the UK. Pl. Pathol., 54, 243.
Henricot B., 'First report of Impatiens downy mildew (Plasmopara obducens) in the UK' (2005) 54Pl. Pathol.: 243-.
Henricot B.First report of Impatiens downy mildew (Plasmopara obducens) in the UKPl. Pathol.200554243)| false
Maniatis, T., Sambrook, J. & Fritsch, E.F. (1989): Molecular cloning: a laboratory manual (3rd Vol.). Cold Spring Harbor Laboratory. USA.
Fritsch E.F., '', in Molecular cloning: a laboratory manual, (1989) -.
Fritsch E.F.Molecular cloning: a laboratory manual1989)| false
Mukerji, K.G., Chamola, B.P. & Upadhyay, R.K. (Eds) (1999): Biotechnological approaches in biocontrol of plant pathogens. Kluwer Academic/Plenum Publishers. New York, p. 17.
Upadhyay R.K., '', in Biotechnological approaches in biocontrol of plant pathogens, (1999) -.
Upadhyay R.K.Biotechnological approaches in biocontrol of plant pathogens1999)| false
Riethmüller, A., Voglmayr, H., Göker, M. Weiss, M. & Oberwinkler, F. (2002): Phylogenetic relationships of the downey mildews (Peronosporales) and related groups based on nuclear large subunit ribosomal DNA sequences. Mycologia., 94, 834–849.
Oberwinkler F., 'Phylogenetic relationships of the downey mildews (Peronosporales) and related groups based on nuclear large subunit ribosomal DNA sequences' (2002) 94Mycologia.: 834-849.
Oberwinkler F.Phylogenetic relationships of the downey mildews (Peronosporales) and related groups based on nuclear large subunit ribosomal DNA sequencesMycologia.200294834849)| false