Determination of physiological race of powdery mildew and its virulence to different melon genotypes

Sphaerotheca fuliginea is the major agent causing powdery mildew throughout the spring season in Hangzhou. The leaf disk assay of the differential melon lines clearly demonstrated that physiological race of Sphaerotheca fuliginea is Race 2. A good linear relationship was found between the results from leaf disk assay and those from field survey of whole plants for resistance to powdery mildew. In this experiment, 24 genotypes were found with resistance to powdery mildew race 2 among 87 melon genotypes.