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Inheritance of Resistance to Powdery Mildew in Cucumber. S. Shanmugasundaram, Plant Pathologist, Wisconsin Agricultural Experiment Station, Madison, Wisconsin 53706; P. H. Williams(2), and C. E. Peterson(3). (2)Plant Pathologist, Wisconsin Agricultural Experiment Station, Madison, Wisconsin 53706; (3)Horticulturist, Plant Science Research Division, ARS, USDA, Madison 53706. Phytopathology 61:1218-1221. Accepted for publication 17 May 1971. DOI: 10.1094/Phyto-61-1218.

Resistance to powdery mildew in cucumber is controlled by a major recessive gene s. This recessive gene s determines hypocotyl (intermediate) resistance and is also essential for leaf (complete) resistance. Leaf resistance is controlled by dominant gene R, which only expresses itself in the presence of recessive gene s. Gene I is an inhibitory gene which prevents the expression of complete resistance, but does not affect gene s. The genes responsible for resistance in cultivars P.I. 212233, P.I. 234517, and Natsufushinari appear to be the same. Genes for powdery mildew resistance, scab resistance, cotyledon bitterness, and spine color are all independently inherited, and no linkage was observed between them.