Strawberry is an important source of early-season income on farms across New England (Bornt et al., 1998; Grubinger, 2012), where it is estimated there are more than 1000 acres in production on 884 farms (U.S. Department of Agriculture National Agricultural Statistics Service, 2018) and locally produced strawberry fruit are highly regarded by consumers. Short-day cultivars (June-bearers) have long been popular in the region for their winterhardiness and low establishment costs (Black et al., 2002; Pritts and Handley, 1998), but regional dependence on these cultivars has prevented growers from participating in the commercial strawberry market outside their brief 4- to 6-week fruiting period each year (Pritts and Handley, 1998).
Day-neutral (DN) strawberry cultivars are less affected by daylength and typically continue to flower as long as temperatures remain between 40 and 85 °F, resulting in a substantially longer fruiting period compared with short-day plants (Pritts and Handley, 1998; Rowley et al., 2010). Furthermore, DN plants produce ripe fruit ≈10 weeks after planting, not the following year as with short-day plants (Pritts and Handley, 1998), reducing the period of crop management before financial return (Bornt et al., 1998).
DN cultivars have largely been developed for regions of the United States with substantial acreage in strawberry production, namely California and Florida (Lawrence et al., 1990). However, following the adoption of the plasticulture production system (Poling, 1993), early field trials in North Carolina showed that cultivars could produce as much as 1.02 kg/plant annually on the east coast of the United States (Ballington et al., 2008), suggesting great potential for DN production across the country. Recently, cultivar evaluations conducted from the mid-Atlantic region of the United States to as far north as Quebec, Canada, indicate that DN productivity is influenced by cultivar, site, and growing season, and annual marketable yields have ranged from between 189 and 950 g/plant (Condori et al., 2017; Lewers et al., 2017; Petran et al., 2016; Pritts, 2017a; Pritts and McDermott, 2017; Van Sterthem et al., 2017; Weber et al., 2018). Using a standard plasticulture plant spacing of 17,424 plants/acre (Lantz et al., 2010) such yields equate to between 8137 and 40,902 kg·ha−1, well exceeding the 5900 lb/acre (6613 kg·ha−1) harvested by New England growers (U.S. Department of Agriculture National Agricultural Statistics Service, 2018). This strongly suggests that DN strawberry cultivars may not only extend the fruiting period, but also offer high annual yields compared with short-day plants.
There are only a limited number of commercial farmers growing DN cultivars in New England. Anecdotally, the cultivars Albion, San Andreas, and Seascape are the most commonly grown, with select farmers reporting yields exceeding 25,000 lb/acre. While there have been exploratory trials at universities in the region (Handley, 2008; A. Radin, personal communication), to our knowledge, no replicated studies have been published and yield data are not available. Studies outside New England show tremendous variation in annual yield among sites, highlighting the need for region-specific research. For example, ‘Seascape’ was among the lowest yielding cultivars in Minnesota, but among the highest yielding in Maryland and New York (Lewers et al., 2017; Petran et al., 2016; Pritts, 2017a).
Several studies have found that low tunnel protective structures increase the marketable yield (grams per plant) and/or the percent marketable yield, especially late in the season and following weather events (Lewers et al., 2017; Petran et al., 2016; Pritts, 2017a; Resende et al., 2010; Van Sterthem et al., 2017). This suggests that low tunnels may be a useful tool for protecting fruit marketability in regions with frequent precipitation events, such as throughout the northeastern United States, but little is known about low tunnel effects on plant growth and development.
Of particular interest is runner initiation, which has been cited as a barrier for the adoption of the plasticulture cultivation system (Handley et al., 2009). While runner removal is standard practice in plasticulture production (Voth and Bringhurst, 1990), many growers converting from the perennial matted-row cultivation system [where runners are not removed (Poling and Durner, 1986)], find the task costly and time consuming because substantial labor is required to remove runners by hand (Handley et al., 2009). The gibberellic acid synthesis inhibitor prohexadione-calcium (commonly known as Apogee; BASF Corp., Research Triangle Park, NC) has been approved in Canada to assist with runner management (BASF Canada, Mississauga, ON, Canada). However, despite trials in Maryland, Massachusetts, and Maine showing that applications can significantly reduce runner initiation and even improve fruit yields in strawberry (Black, 2004; Green and Schloemann, 2010; Handley et al., 2009), the product has not been approved in the United States. Thus, other tools are needed.
Lewers (2013) has reported observing a reduction in runner emergence under low tunnels in field trials in Maryland, but to our knowledge, these effects have not been documented in any published studies. However, they are in line with other research showing the cultivars Chandler and Sweet Charlie produced fewer runners under high tunnel protected culture (Kadir et al., 2006). Total leaf area, shoot biomass (grams), leaf number, and the number of branch crowns have also been affected by high tunnels (Kadir et al., 2006), suggesting that protected culture may also influence plant size and even planting density.
Furthermore, recent experiments comparing the microclimate under low tunnels with the traditional open bed environment have reported that season-long air and soil temperatures are greater under low tunnels (Condori et al., 2017; Van Sterthem et al., 2017). Warmer temperatures have been associated with greater yields and an extended fruiting season, especially in the mid-Atlantic region where temperatures are milder than the northeastern United States (Condori et al., 2017; Lewers et al., 2017; Van Sterthem et al., 2017). Given these findings, it is important to understand the effect of low tunnels on microclimate and season duration in the northeastern United States, where summers are hot but nighttime temperatures can drop precipitously in the fall. Of particular interest is whether low tunnels increase temperatures during the summer months even when low tunnels are vented, and whether they provide any thermal insulation at night during the fall months, when they may be used to assist in season-extension. Experiments conducted in warmer regions suggest low tunnels do not provide a substantial buffer in nighttime temperatures (Condori et al., 2017; Van Sterthem et al., 2017), but since most studies present season-long averages, not daily fluctuations in temperature, this remains unclear.
The objectives of this study were to quantify the effects of low tunnel structures and DN cultivar on yield, fruit marketability, and fruit and plant characteristics. We were also interested in the impact of low tunnels on air and soil temperatures. Toward this end, we evaluated five relatively well-known DN cultivars: Albion, Monterey, Portola, San Andreas, and Seascape, as well as three additional cultivars that may be candidates for our region: Aromas, Cabrillo, and Sweet Ann. Plants were grown on two production systems (called cover treatments): open beds and low tunnels. Data were collected on yield, fruit weight, the fruiting pattern of cultivars throughout the season (called fruiting pattern), fruit SSC, runner emergence, plant height, plant diameter, and average, maximum, and minimum air and soil temperatures.
Anderson, H. 2017 Effects of low tunnel plastic type on organic production of day-neutral strawberries in the upper Midwest HortScience 52 S442 S443 (abstr.)
Awang, Y.B. & Atherton, J.G. 1995 Growth fruiting responses of strawberry plants grown on rockwool to shading and salinity Scientia Hort. 62 25 31
Bagdasarian, J.H. 2012 Strawberry plant named ‘Sweet Ann’. U.S. Plant Patent PP22,472 P3. Filed 24 Feb. 2009. Issued 31 Jan. 2012
Ballington, J.R., Poling, B. & Olive, K. 2008 Day-neutral strawberry production for season extension in the Midsouth HortScience 43 1982 1986
Black, B.L. 2004 Prohexadione-calcium decreases fall runners and advances branch crowns of ‘Chandler’ strawberry in a cold-climate annual production system J. Amer. Soc. Hort. Sci. 129 479 485
Black, B.L., Enns, J.M. & Hokanson, S.C. 2002 A comparison of temperate-climate strawberry production systems using eastern genotypes HortTechnology 12 670 675
Bornt, C.D., Loy, J.B., Lord, W.G. & Wells, O.S. 1998 Annual strawberry production in New England Proc. Natl. Agr. Plastics Congr. 27:99–105
Bringhurst, R.S. & Voth, V. 1991 Strawberry plant named ‘Seascape’. U.S. Plant Patent 7,614. Filed 13 Feb. 1990. Issued 6 Aug. 1991
Capocasa, F., Balducci, F., Martellini, C. & Albanesi, A. 2017 Yield and fruit quality of strawberry cultivars grown in organic farming in the mid-Adriatic area Acta Hort. 1156 619 626
Condori, B., Fleisher, D.H. & Lewers, K. 2017 Relationship of strawberry yield with microclimate factors in open and covered raised-bed production Trans. Amer. Soc. Agr. Biol. Eng. 60 5 795 810
Connor, D.S. & Demchak, K. 2018 Farmer perceptions of tunnels for berry production: Management and marketing implications HortTechnology 28 706 710
Correia, P.J., Pestana, M., Martinez, F., Ribeiro, E., Gama, F., Saavedra, T. & Palencia, P. 2011 Relationship between strawberry fruit quality attributes ad crop load Scientia Hort. 130 2 795 810
Durner, E.F., Barden, J.A., Himelrick, D.G. & Poling, E.B. 1984 Photoperiod and temperature effects on flower and runner development in day-neutral, junebearing, and everbearing strawberries J. Amer. Soc. Hort. Sci. 109 396 400
Galletta, G.J. & Bringhurst, R.S. 1990 Strawberry management, p. 109–112. In: G.J. Galletta and D.G. Himekick (eds.). Small fruit management. Prentice Hall, Englewood Cliffs, NJ
Green, D.W. & Schloemann, S.G. 2010 Prohexadione-calcium inhibits runner formation and enhances yield of strawberry J. Amer. Pomol. Soc. 64 3 795 810
Grubinger, V. 2012 History of the strawberry. 11 Feb. 2019. <https://www.uvm.edu/vtvegandberry/factsheets/strawberryhistory.html>
Handley, D. 2008 Strawberry varieties for Maine: How do I grow strawberries in the off-season? Univ. Maine Ext. Bul. 2184. 4 Feb. 2019. <https://extension.umaine.edu/publications/2184e/>
Handley, D. 2017 Getting started in strawberries – Plasticulture. New England Veg. Fruit Conf. Trade Show Proc. p. 79–83
Handley, D.T., Dill, J.F. & Moran, R.E. 2009 Prohexadione-calcium applications to suppress runner growth in strawberries grown in a plasticulture system Acta Hort. 842 801 804 (abstr.). doi:10.17660/ActaHortic.2009.842.176
Kadir, S., Sidhu, G. & Al-Khatib, K. 2006 Strawberry (Fragaria x ananassa Duch.) growth productivity as affected by temperature HortScience 41 1423 1430
Kirschbaum, D.S., Adlercreutz, E.G.A. & Gariglio, N. 2017 Growth and production patterns of strawberries grown in the Atlantic coast of Argentina Acta Hort. 1156 941 946
Lantz, W., Swartz, H., Demchak, K. & Frick, S. 2010 Season-long strawberry production with everbearers for northeastern producers. Univ. Maryland Ext. EB 401
Laugale, V., Dane, S., Lepse, L., Strautina, S. & Kalnina, I. 2017 Influence of low tunnels on strawberry production time and yield Acta Hort. 1156 573 578
Lawrence, F.J., Galletta, G.J. & Scott, D.H. 1990 Strawberry breeding work of the United States Department of Agriculture HortScience 25 895 896
Ledesma, N.A. & Kawabata, S. 2016 Response of two strawberry cultivars to severe high temperature stress at different flower development stages Scientia Hort. 211 319 327
Ledesma, N.A., Nakata, M. & Sugiyama, N. 2008 Effect of high temperatures stress on reproductive growth of strawberry cvs. ‘Nyoho’ and ‘Toyonoka’ Scientia Hort. 116 186 193
Legard, D.E., Xiao, C.L., Mertely, J.C. & Chandler, C.K. 2000 Effects of plant spacing and cultivar on incidence of Botrytis fruit rot in annual strawberry Plant Dis. 84 5 795 810
Lewers, K. 2013 Strawberry season extension using low tunnels. 4 Feb. 2019. <http://www.hort.cornell.edu/expo/proceedings/2013/Berries/Berries%20Lewers%20Low%20TTunnel.pdf>
Lewers, K.S., Fleisher, D.H. & Daughtry, C.S.T. 2017 Low tunnels as a strawberry breeding tool and season-extending production system Intl. J. Fruit Sci. 17 3 795 810 doi: 10.1080/15538362.2017.1305941
Nicoll, M.F. & Galletta, G.J. 1987 Variation in growth and flowering habits of June-bearing and everbearing strawberries J. Amer. Soc. Hort. Sci. 112 872 880
Nobel, P.S. 2005 Physicochemical and environmental plant physiology. 3rd ed. Elsevier Sci. Technol./Academic Press. Oxford, UK
Pérez De Camacaro, M.E., Camacaro, G.J., Hadley, P., Dennett, M.D., Battey, N.H. & Carew, J.G. 2004 Effect of plant density and initial crown size on growth, development and yield in strawberry cultivars Elsanta and Bolero J. Hort. Sci. Biotechnol. 79 5 795 810
Petran, A., Hoover, E., Hayes, L. & Poppe, S. 2016 Yield and quality characteristics of day-neutral strawberry in the United States upper Midwest using organic practices Biol. Agr. Hort. 33 2 795 810
Pistón, F., Pérez, A.G., Sanz, C. & Refoyo, A. 2017 Relationship between sugar content and °Brix as influenced by cultivar and ripening stages of strawberry Acta Hort. 1156 491 496
Poling, E.B. 1993 Strawberry plasticulture in North Carolina: II. Preplant, planting, and postplant considerations for growing ‘Chandler’ strawberry on black plastic mulch HortTechnology 3 383 393
Pritts, M. 2017a Protected culture for berries, low and high tunnel research. 8 Mar. 2018. <https://www.youtube.com/watch?v=5ErlnTZNuxM>
Pritts, M. 2017b Low tunnel strawberry production. New England Veg. Fruit Conf. Trade Show Proc. p. 87–98
Pritts, M. & Handley, D. 1998 Strawberry production guide for the Northeast, Midwest, and eastern Canada. Northeast Reg. Agr. Eng. Serv. (NRAES), Ithaca, NY
Pritts, M. & McDermott, L. 2017 Protected culture for strawberries using low tunnels. 11 Feb. 2019. <http://www.hort.cornell.edu/fruit/pdfs/low-tunnel-strawberries.pdf>
Resende, J.T.V., Morales, R.G.F., Faria, M.V., Rissini, A.L.L., Camargo, L.K.P. & Camargo, C.K. 2010 Produtividade e teor de sólidos solúveis de frutos de cultivares de morangueiro em ambiente protegido Hort. Bras. 28 185 189
Rowley, D., Black, B. & Drost, D. 2010 High tunnel strawberry production. 4 Feb. 2019. <https://digitalcommons.usu.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpshttps=1&article=1709&context=extension_curall>
Ruan, J., Lee, Y.H., Hong, S.J. & Yeoung, Y.R. 2013 Sugar and organic acid contents of day-neutral and ever-bearing strawberry cultivars in high-elevation for summer and autumn fruit production in Korea Hort. Environ. Biotechnol 54 3 214:222
Salamé-Donoso, T.P., Santos, B.M., Chandler, C.K. & Sargent, S.A. 2010 Effect of high tunnels on the growth, yields, and soluble solids of strawberry cultivars in Florida Intl. J. Fruit Sci 10 3 795 810 (abstr.)
Shaw, D.V. 1998 Strawberry plant named ‘Aromas'. U.S. Plant Patent 10,451. Filed 12 Nov. 1996. Issued 16 June 1998
Shaw, D.V. & Larson, K.D. 2006 Strawberry plant named ‘Albion’. U.S. Plant Patent 16,228 P3. Filed 29 Jan. 2004. Issued 31 Jan. 2006
Shaw, D.V. & Larson, K.D. 2016 Strawberry plant named ‘Cabrillo’. U.S. Plant Patent 2016/0227687 P1. Filed 30 Jan. 2015. Issued 4 Aug. 2016
Shaw, D.V. & Larson, K.D. 2009a Strawberry plant named ‘Monterey’. U.S. Plant Patent PP19,767 P2. Filed 25 Jan. 2008. Issued 24 Feb. 2009
Shaw, D.V. & Larson, K.D. 2009b Strawberry plant named ‘Portola’. U.S. Plant Patent PP20,552 P3. Filed 6 Nov. 2007. Issued 15 Dec. 2009
Shaw, D.V. & Larson, K.D. 2009c Strawberry plant named ‘San Andreas’. U.S. Plant Patent PP19,975 P2. Filed 25 Jan. 2008. Issued 12 May 2009
Tabatabaei, S.J., Yusefi, M. & Hajiloo, J. 2008 Effects of shading and NO3:NH4 ratio on the yield, quality and N metabolism in strawberry Scientia Hort. 116 264 272
Takaichi, M., Shimaji, H. & Higashide, T. 2000 Effects of red/far-red photon flux ratio of solar radiation on growth of fruit vegetable seedlings Acta Hort. 514 147 156 doi: 10.17660/ActaHortic.2000.514.16
University of New Hampshire 2016 Commercial fruit soil report: Recommendations. Univ. New Hampshire Ext. Soil Lab. Rpt., Durham
University of New Hampshire 2018 Weather statistics. 26 Nov. 2018. <http://www.weather.unh.edu>
U.S. Department of Agriculture 2012 Plant hardiness zone map. 11 Mar. 2019. <https://planthardiness.ars.usda.gov/PHZMWeb/>
U.S. Department of Agriculture National Agricultural Statistics Service 2018 New England vegetable and strawberry report, 2017 crop. U.S. Dept. Agr., Washington, DC
U.S. Department of Agriculture Natural Resource Conservation Service 2016 Soil series classification: Charlton. 25 Mar. 2019. <https://soilseries.sc.egov.usda.gov>
Van Sterthem, A., Desjardins, Y., Gauthier, L., Medina, Y. & Gosselin, A. 2017 Use of low tunnels to improve the productivity of day-neutral strawberry plants under the Québec climatic conditions Acta Hort. 1156 555 562
Voća, S., Duralija, B., Družić, J., Skendrović Babojelić, M., Dobričević, N. & Čmelik, Z. 2007 Influence of cultivation systems on physical and chemical composition of strawberry fruits cv Elsanta. Agr. Conspectus Sci. 71 4 795 810
Weber, C., Gassier, R., Kuehn, K. & Pritts, M.P. 2018 Yield of day-neutral strawberries grown under low tunnels is affected by planting date HortScience 53 S171 (abstr.)