Traditionally, commercial production of sweetpotatoes (Ipomoea batatas) has concentrated in the warmer states of the United States, with North Carolina, California, Arkansas, Florida, Louisiana, and Mississippi demonstrating more than 94% of total area planted for 2018 [U.S. Department of Agriculture (USDA), National Agricultural Statistics Service (NASS), 2020]. In stark contrast, the northeastern United States [defined here as the conjunct of states conforming the subregions of New England and the mid-Atlantic (in all, Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont)] accounts for only ≈1300 acres (1.2% of the total U.S. acreage) harvested for fresh-market sweetpotatoes in 2017 (USDA, NASS, 2019). For that reason, the majority of sweetpotatoes consumed in the northeastern United States are shipped and distributed from southern U.S. states such as North Carolina and Louisiana.
Yet, sweetpotato is considered a resilient crop, well adapted to low- and high-input systems, and numerous types of soils and climates (Jansson and Raman, 1991), with their North American distribution ranging from Florida to southern Ontario, Canada (Bouwkamp, 1985). Progressively, more and more sweetpotato production research studies under shorter growing seasons and milder temperatures have been published (Sideman, 2015; Wees et al., 2015, 2016).
Pennsylvania’s sweetpotato acreage has grown slowly but steadily and now accounts for more than 4% of the total acreage harvested in the northeastern United States (USDA, NASS, 2019). The majority of Pennsylvania farmers plant and harvest sweetpotatoes as part of a diversified farmstead, with sweetpotato acreage fluctuating between 1 and 2 acres. Typically, farmers outsource second generation (G2) sweetpotato slips from certified producers in southern U.S. states, opting to purchase vigorous disease- and virus-free slips as opposed to producing slips themselves.
Still, the greatest challenges for sweetpotato production in the northeastern United States including Pennsylvania are 1) a short growing season, 2) cool temperatures, 3) erratic and unpredictable rainfall patterns, and 4) nonadapted varieties, among many others. Northern and central Pennsylvania growers cannot plant in early spring because of cold soil temperatures, and must harvest early in the fall season before the first frost, resulting in a shorter growing season. One strategy is the use of raised beds coupled with black biodegradable or standard black plastic mulch films to increase early-season soil temperature and control for weeds (Hayes et al., 2019). However, there are increased labor, machinery, and supply costs associated with initial placement and subsequent removal and disposal of plastic after final harvest. This strategy has been examined extensively and was found to increase vegetable yields (Hayes et al., 2019). Another important factor for sweetpotato production is the use of adapted sweetpotato varieties that could yield well under northeastern U.S. conditions, as well as present suitable shapes and quality characteristics for local fresh markets.
Numerous studies have shown the positive impact of plastic mulch on the growth of sweetpotato both in the United States and Canada. In New Hampshire, Sideman (2015) examined sweetpotato growth using both biodegradable and nondegradable black plastic mulch, with variable results depending on varieties tested. In Iowa, Nair et al. (2012) tested different colored plastic mulches using ‘Beauregard’ and ‘Evangeline’. Their results demonstrated no statistically significant differences between the different color mulches tested with regard to final yield. In New York, Bornt (2012) used traditional black plastic mulch and infrared transmitting mulch with no statistically significant differences in yield among the sweetpotato varieties examined. In Canada, Wees et al. (2015, 2016) examined more than 15 sweetpotato varieties under biodegradable and nondegradable black plastic mulch and different planting densities. Their results were variable under these conditions, but suggested that both ‘Georgia Jet’ and ‘Beauregard’ were better adapted to higher latitudes compared with OF varieties such as Covington, Diane, Evangeline, Ginseng Red, Hernandez, and Porto Rico.
The objective of this study was to determine the performance and adaptability of eight commercial sweetpotato varieties and two unreleased accessions for production and direct marketing in Pennsylvania conditions under black plastic mulch in a mild temperate climate. The results of these evaluations over 2 years in Rock Springs, PA, are described.
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