The genus Cucurbita includes ca 14 species native to the New World from the United States south to Argentina. It includes at least five different species domesticated before European contact (Sanjur et al., 2002). In many parts of the world, these domesticated species are widely cultivated as vegetables and, to a lesser extent, as oilseeds, animal forages, and ornamentals. Wild populations of Cucurbita often possess disease-resistance genes that are unknown or extremely rare in domesticated populations. This has been demonstrated for resistance to many viruses and fungal pathogens that infect Cucurbita (Rhodes, 1964; Provvidenti, 1990; McCreight and Kishaba, 1991; Munger, 1993; Provvidenti, 1993). Extensive research has also been conducted to transfer disease-resistance genes from wild species into modern Cucurbita cultivars (Contin and Munger, 1977; de Vaulx and Pitrat, 1979; Washek and Munger, 1983; Whitaker and Robinson, 1986; Herrington et al., 1988a, 1988b, 1989; Robinson et al., 1988; Tasaki and Dusi, 1990).