Resistance to Peronospora parasitica in Chinese Cabbage. J. E. Yuen, Former Associate Plant Pathologist, The Asian Vegetable Research and Development Center, Shanhua, Tainan 741, Taiwan. Plant Dis. 75:10-13. Accepted for publication 24 April 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0010.

Some Chinese cabbage (Brassica campestris subsp. pekinensis) lines developed at The Asian Vegetable Research and Development Center, both open-pollinated and F₁ hybrids, are moderately resistant to downy mildew caused by Peronospora parasitica. In field trials, these lines had a reduced rate of disease increase when disease was measured as either percentage of leaf area infected or number of diseased leaves. Resistant lines had fewer and smaller lesions than the susceptible check 7–9 days after inoculation. In vitro tests with detached cotyledons showed a reduced rate of sporulation in resistant lines, with no evidence of maternal effects in hybrids. Comparisons of F₁ hybrids and their parents tested in vitro suggest that resistance may be an additive characteristic.