The results of studies of (Plasmopara halstedii Farl.) Berl. et de Toni population (the causative agent of sunflower downy mildew) in the south of the Russian Federation in 2016-2018 have been shown. Seven races of the pathogen were found. For the first time races 713, 733 and 734 were registered in the Russian Federation, and races 733 and 734 - in the territory of Europe and Asia. The simultaneous presence of different P. halstedii races in the sunflower plant was revealed. It was established that there are resistant biotypes among races 710, 730 and 734 to mefenoxam, among races 713 and 734 - to thiram.