Evaluation of Pumpkin Cultivars for Powdery and Downy Mildew Resistance, Virus Tolerance, and Yield

Twenty-six cultivars and two numbered selections of Cucurbita pepo L. pumpkin and four cultivars of C. maxima Duchesne pumpkin were evaluated in field experiments in 1996 and 1997 in Charleston, S.C. The four C. maxima cultivars ('Mammoth Gold', 'Big Max', 'Rouge Vif d'Etamps', and 'Lumina') and three C. pepo cultigens (HMX 6686, HMX 6688, and Magic Lantern) had lower powdery mildew (Sphaerotheca fuliginea (Schlechtend.:Fr.) Pollacci) severities than did the other C. pepo cultivars. Overall, C. maxima cultivars also had less foliage showing virus symptoms and less downy mildew (Pseudoperonospora cubensis (Berk.& M.A. Curtis) Rostovzev) than did C. pepo cultigens. Mid- and long-season cultigens of both species (≥100 days to maturity) produced a greater number of marketable-quality fruit than did short-season cultigens. Cucurbita maxima and C. pepo produced similar numbers of marketable fruit; however, more potential marketable yield was possible in C. maxima since most fruit were affected by virus. The C. pepo cultigens Spookie, HMX 6686, and Spooktacular produced the greatest numbers of marketable fruit. In general, no cultigens were well-adapted to the growing conditions of the humid coastal plain of the southeastern United States. Pumpkin can be a profitable crop when grown for the Halloween market. Because of the high potential return per hectare, pumpkin is particularly suited for growers with limited acreage or those located near urban areas. To yield well under current management prac- tices, pumpkin requires expensive inputs, such as white or black polyethylene mulch and regular insecticide and fungicide applications (Kemble et al., 1997). Because pumpkin has a long growing season (90 to 120 d) and is planted later than most warm-season vegetable crops, vines must be protected from several foliar pathogens. In the southeastern United States, both downy mildew and powdery mil- dew reduce yields (Bost et al., 1991; Shoe- maker, 1994). In addition, viruses such as papaya ringspot virus (PRSV), watermelon mosaic virus (WMV), and zucchini yellow mosaic virus (ZYMV) infect C. pepo and reduce marketable yields in this region (Schultheis and Walters, 1998). Little infor-