First Report of Plasmopara halstedii New Races 705 and 715 on sunflower from the Czech Republic - Short Communication

Abstract

Downy mildew caused by Plasmopara halstedii significantly reduces annual yields of sunflower. At least 42 races of P. halstedii have been identified around the world. For the first time to our knowledge, races 705 and 715 of P. halstedii have been isolated, originating from sunflower plants collected at a single site (Podivín, South-East Moravia) in the Czech Republic at the beginning of June 2014. This enlarges the global number of the so far identified and reported races of P. halstedii to 44. The increasing complexity of P. halstedii pathogenicity led to race identification newly by a five-digit code. According to this new nomenclature, the two races of P. halstedii recorded in the Czech Republic are characterised by virulence profiles 705 71 and 715 71.

Keywords

• helianthus annuus
• resistance
• sunflower downy mildew
• virulence formula