First Korean report of downy mildew on Coreopsis lanceolata caused by Plasmopara halstedii.
In October 2008, Coreopsis lanceolata plants showing typical symptoms of downy mildew disease were first collected in Pocheon County of Korea Republic. Infected leaves turned yellow or pale green, with a whitish fungal-like downy growth developing on the abaxial leaf surface. As the disease progressed, the leaves wilted and curled. Detailed microscopic examinations of three representative samples (KUS-F23701, KUS-F23741, KUS-F23742) were made to identify the pathogen. Based on the morphology, the pathogen was identified as Plasmopara halstedii. To confirm the identification, the D1-D3 region of the 28S rDNA was amplified and sequenced, and the resulting sequence deposited in GenBank (Accession No. FJ638471). Comparison with the sequences available at GenBank revealed that the isolate shared 100% similarity with sequences EF553469 and AY035523 of Plasmopara halstedii on Helianthus annuus. This is the first report of downy mildew disease on Coreopsis spp. in Asia.