Appearance of a new sunflower downy mildew race in the South-East region of the Hungarian Great Plain.
The downy mildew is an economically significant disease. It is caused by the fungus Plasmopara halstedii (Farl.) Berl. et de Toni. (syn. Plasmopara helianthi Nov.). This species is widespread in all sunflower-growing countries with the exception of Australia. To date 35 different races of Plasmopara halstedii have been discovered, of which only five are prevalent (300, 330, 710, 730, 770). In Hungary, five races (100, 700, 730, 710, 330) have been identified so far. However, in 2010 a strong infection of Plasmopara halstedii formed in stands of commercial sunflower hybrids, in a few fields of Tiszántúl in consequence of the climatic conditions, which were much cooler and more rainy than the average. The samples were collected in July, near Vésztő and Kondoros in the South-East part of the Hungarian Great Plain. In the course of analysing the samples for reactions to differential genotypes it has been proved that samples belong to the race 704, which was unknown so far in Hungary. It may be hypothesized that the new race have spread in consequence of favorable environmental conditions in major area, or some new races have already appeared in Tiszántúl region. Therefore, the reidentification of Hungarian downy mildew races and remapping of their occurrence would be of primary importance.