Physiological Races Identification of Powdery Mildew On Cucurbits in Heilongjiang Province

Powdery mildew is one of the most important diseases attacking cucurbits in greenhouses and open-field. The disease can be caused by three fungal species, Sphaerotheca fuliginea, Erysiphe cichoracearum and Leveillula taurica, but S. fuliginea is the most commonly species in China. The powdery mildew physiological races infected cucurbits change quickly. Consequently, knowledge on the prevalence and geographic distribution of these races is essential for the choice of appropriate strains to be used in breeding programs and for the implementation of gene deployment strategies.

     Eighteen powdery mildew samples were isolated from mildewed melon, cucumber, pumpkin and squash grown in greenhouse or open field of seven different ecological regions in Heilongjiang Province in 2009, then were detected using the standard identification system of powdery mildew. According to performance on thirteen hosts which are universal in the world, one strain came from cucumber of Mudanjiang was classified as race N1, while others were race 1. This study preliminarily confirmed that race 1 of Sphaerotheca fuliginea was the dominant race which infected cucurbits. It also provided basis for cucurbits resistance variety breeding in Heilongjiang.

Key words: Cucurbits, Powdery mildew, Physiological race identification