Although the fresh market strawberry industry in the United States is overwhelmingly dominated by California and Florida, small-scale production continues throughout much of North America, particularly in proximity to urban centers where fresh local produce commands premium prices. Demand for local produce continues to increase with the developing local food movement despite environmental conditions in many areas that are less than ideal for strawberry production. Ideal conditions for strawberries occur when temperatures are between 20 and 26 °C. Suboptimal temperatures (less than 20 °C) retard the growth and development of both the strawberry plant and fruit, whereas superoptimal temperatures (greater than 35 °C) cause the strawberry plant to stop growing (Galletta and Bringhurst, 1990).
Fall-planted June-bearing cultivars in an annual hill production system have proven effective for focusing fruit production in the early spring (Black et al., 2002; Poling, 1993; Stevens et al., 2011), but length of fruiting season is limited by photoperiod and temperature (Durner et al., 1984). Alternatively, day-neutral cultivars are insensitive to photoperiod and continue to flower as long as temperatures are between 4 and 29 °C (Hancock and Handley, 1998; Pritts and Dale, 1989). In many production areas including the northeast United States, day-neutral cultivars are increasingly being used to extend the growing season and produce strawberries throughout the summer. Day-neutral plants are established in the early spring, come into production near the end of the June-bearing production season, and continue to fruit through the summer and fall months (Pritts and Dale, 1989).
Conditions in the high-elevation valleys of the Intermountain West region of the United States (Utah, Idaho, Nevada, western Colorado) are particularly challenging for strawberry production. Early spring temperatures are generally suboptimal and transition rapidly to summer temperatures that are typically superoptimal (Moller and Gillies, 2008). Wide diurnal temperature fluctuations in early spring also limit strawberry production in the region, and there is not sufficient water available for spring frost protection. The production window for field-grown June-bearing strawberries also coincides with peak national production and depressed wholesale prices (Pollack and Perez, 2008). The short growing season and depressed prices often make strawberry production in the region only marginally profitable.
High tunnels have been successfully used to manipulate temperature and extend the growing season for a number of crops, including flowers (Rasmussen and White, 2006), vegetables (Orzolek et al., 2006), and small fruits (Demchak, 2009; Demchak et al., 2006). We previously showed that high tunnels could be used effectively in high-elevation, arid regions in the western United States to advance the production season of June-bearing strawberries with the added benefit of protecting early blossoms from frost, resulting in increased early and total yield and greater potential profitability (Rowley et al., 2010b, 2010c). Extending the production season later into the summer and fall would require day-neutral cultivars and additional temperature management strategies. Low tunnels can be used inside high tunnels to further increase temperatures for plant growth and have been used in a number of crops with varied success (McIntosh and Klingaman, 1993; Roberts and Whitworth, 1993; Takeuchi and Motsenbocker, 2005). Low tunnels are typically only 40 to 50 cm tall and cover only one row or one bed of strawberries (Galletta and Bringhurst, 1990). Replacing high-tunnel plastic with shadecloth during the warmest summer months is another method for passive manipulation of growing temperatures.
The focus of this study was to optimize management systems for late-season extension of strawberry production in the Intermountain West region of the United States. Specific objectives for this study were to quantify the season extension benefits that result from using day-neutral cultivars in high tunnels, to identify a suitable day-neutral cultivar for high tunnel production, to examine temperature manipulation methods for use in combination with high tunnels to optimize growing conditions, and to examine the possibility of using summer-planted plug plants for increased fall production.
Ballington, J.R., Poling, B. & Olive, K. 2008 Day-neutral strawberry production for season extension in the Midsouth HortScience 43 1982 1986
Black, B., Drost, D., Rowley, D. & Heflebower, R. 2008 Construction a low-cost high tunnel Utah State University Extension bulletin # HG/High Tunnels/2008-01pr. Utah State University Logan, UT <http://extension.usu.edu/files/publications/publication>.
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
Demchak, K., Lamont, W.J. & Orzalek, M.D. 2006 High tunnel bramble and strawberry culture 126 134 High tunnel production manual Pennsylvania State University University Park, PA
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 83 156 Galletta G.J. & Himelrick D.G. Small fruit crop management Prentice Hall Englewood Cliffs, NJ
Hancock, J. & Handley, D. 1998 The history and biology of the cultivated strawberry 3 6 Strawberry production guide for the Northeast, Midwest, and Eastern Canada Northeast Regional Agricultural Engineering Service (NRAES) Ithaca, NY
Koester, K. & Pritts, M. 2003 Greenhouse raspberry production guide Cornell University Ithaca, NY 7 Oct. 2011. <http://www.fruit.cornell.edu/berry/production/pdfs/ghrasp.pdf>.
McIntosh, G. & Klingaman, G. 1993 A season extension technique for cool season vegetables using poly tunnels and row covers HortScience 28 269
Orzolek, M., Lamont, W. & Burkhart, E. 2006 High tunnel vegetable crop production 117 125 High tunnel production manual Pennsylvania State University University Park, PA
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. & Dale, A. 1989 Day neutral strawberry production guide Information bulletin 215 Cornell Cooperative Extension Ithaca, NY 7 Oct. 2011. <http://ecommons.cornell.edu>.
Rasmussen, C. & White, L. 2006 High tunnel cut flower production 135 149 High tunnel production manual Pennsylvania State University University Park, PA
Rowley, D. 2010 Season extension of strawberry and raspberry production using high tunnels MSc thesis Utah State University Logan, UT
Rowley, D., Black, B. & Drost, D. 2010a Strawberry plug plant production Utah State University Extension bulletin Horticulture/High Tunnels/2010-02pr. Utah State University Logan, UT 7 Oct. 2011. <http://extension.usu.edu/publications>.
Rowley, D., Black, B.L., Drost, D. & Feuz, D. 2010b Early-season extension using June-bearing ‘Chandler’ strawberry plants in high-elevation high tunnels HortScience 45 1464 1469
Rowley, D., Black, B.L. & Feuz, D. 2010c High-tunnel June-bearing strawberry budget 2010 Utah Agricultural Statistics and Utah Department of Agriculture and Food 2010 Annual Report Utah Department of Agriculture and Food Salt Lake City, UT 94
Stevens, M.D., Black, B.L., Lea-Cox, J.D. & Feuz, D. 2011 Horticultural and economic considerations in the sustainability of three cold-climate strawberry production systems HortScience 46 445 451
Takeuchi, K. & Motsenbocker, C.E. 2005 The effect of high tunnels and row covers on air temperatures and spring-planted tomato yield in Louisiana HortScience 40 1055