LOGAN, UT--California and Florida dominate the large-scale production of fresh-market strawberries in the United States, but emerging local food movements have created a demand for small-scale strawberry production in other regions. Challenged by an array of less than ideal environmental conditions, strawberry producers are turning to researchers to find proven methods for extending the strawberry growing season. A recent report showed that high tunnels can be "marginally profitable" for strawberry production in one region of the U.S.
Brent Black, Dan Drost, Dillon Feuz, and Daniel Rowley from Utah State University investigated ways to optimize management systems for late-season extension of strawberry production in the Intermountain West region of the U.S. The team’s report in HortScience revealed some important information for high-elevation production. "Conditions in the high-elevation valleys of this region (Utah, Idaho, Nevada, and western Colorado) are particularly challenging for strawberry production," said author Brent Black. "The short growing season and depressed prices often make strawberry production in the region only marginally profitable." Black explained that ideal strawberry growing conditions occur when temperatures are between 20 °C and 26 °C. "Temperatures less than 20 °C retard the growth and development of both the strawberry plant and fruit, while temperatures greater than 35 °C cause the strawberry plant to stop growing."
The study was designed with several objectives, Black said. "We set out to quantify the benefits of using day-neutral cultivars in high tunnels, to identify a suitable day-neutral cultivar for high tunnel production, to investigate 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."
The experiments were performed in North Logan, Utah, where day-neutral strawberry cultivars 'Albion', 'Evie 2', 'Seascape', and 'Tribute' were spring-planted in an annual hill system both inside and outside of high tunnels. Low tunnels and targeted root zone heating were tested in replicated plots within the high tunnels. During the summer months the researchers removed the plastic from the high tunnels and replaced it with shadecloth. The team evaluated all experimental treatments for yields, fruit size, and production season.
"Our results showed that combinations of high and low tunnels provided more hours of optimal growing conditions than high tunnels alone," Black said, "but managing the combination to maintain optimum temperatures proved difficult with temperatures often exceeding the optimum for strawberry."
The scientists also found that targeted root zone heating efficiently increased root and canopy temperatures, preventing flower bud damage during extreme cold events, but did not significantly improve total season yields. Of the strawberry varieties used in the experiments, 'Evie 2' and 'Seascape' had the most consistent yields and acceptable fruit size.
The authors concluded that the use of low-cost high tunnels could convert a spring-planted day-neutral strawberry system from a money-losing to a marginally profitable enterprise, but added that "unless farmers have high demand for late-summer or fall strawberries, we would not recommend this system for use in the Intermountain West."
"Our economic analysis indicated that growing spring-planted day-neutral strawberries in high tunnels was marginally profitable, whereas field production at this location would be a money-losing enterprise," Black said.
The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/content/46/11/1480.abstract
Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at ashs.org
Late-season Strawberry Production Using Day-neutral Cultivars in High-elevation High Tunnels
Daniel Rowley, Brent L. Black, Dan Drost, and Dillon Feuz
HortScience 46:1480–1485. [Abstract][Full Text][PDF]