Comparison of resistance to powdery mildew and downy mildew in Chinese wild grapes

This research was performed under natural conditions in an effort to compare resistance within Chinese Vitis germplasm to powdery mildew and downy mildew. Sixty-six genotypes of 13 Chinese wild Vitis species were selected to evaluate disease resistance. Seven among these 13 species, V amurensis, V romanetii, V piazezkii, V davidii, V davidii var. cyanocarpa, V liubanensis, and V bashanica showed resistance to powdery mildew. Three species, Vyeshanensis, V davidii var. cyanocarpa, and V pseudoreticulata exhibited resistance to downy mildew. Among 66 genotypes, 46 were resistant to powdery mildew, 28 were resistant to downy mildew and 19 genotypes had resistance to both diseases. Although more than half of the genotypes exhibited resistance to powdery mildew and a lesser number expressed resistance to downy mildew, resistance to both diseases in Chinese Vitis were significantly related (r = 0.395, df = 64, r(0.01) = 0.325). Also, there is resistance variation regarding both diseases between the species and also, to a lesser degree, among the genotypes. The variation is not related to the geographic distribution of the germplasm. These variations should be considered when researchers collect the gemplasm on location, making every effort to obtain extensive genotypes for the breeding program.