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Resistance to Downy Mildew in Cucumis melo Plant Introductions and American Cultivars. Claude E. Thomas, Research Plant Pathologist, USDA, ARS, Oklahoma-Texas Area, Weslaco, TX 78596. Plant Dis. 66:500-502. Accepted for publication 9 September 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982. DOI: 10.1094/PD-66-500.

Twenty-two Cucumis melo plant introductions, 14 cantaloup cultivars, and other selected Cucurbitaceae were evaluated for resistance to downy mildew under epiphytotic conditions at Weslaco, TX, in 1978 and 1979. Only nine plant introductions, all from India, and three cultivars had ≤50% leaf loss due to the disease. The most resistant entry was an inbred derivative of PI 124111. Cucumis sativus and Citrullus lanatus were infected in both years. Luffa cylindrica was not infected in either year. Three species of Cucurbita were infected in 1979 but not in 1978. Artificial inoculations in growth chambers produced the same differential host response that was expressed under field conditions.