Tuesday, August 9, 2016
Georgia Ballroom (Sheraton Hotel Atlanta)
Winter production of organically managed strawberries has been proven feasible and profitable in hardiness zone seven of North Carolina. However, cold damage to open blossoms was inevitable, and a damage rate of 61.5% has occurred in our previous study. The objective of this project was to investigate the possibility of including low tunnels inside high tunnels for reliable winter protection of strawberries. Tips of four strawberry cultivars Albion, San Andrea, Radiance and Winterstar were collected from a commercial nursery and rooted in a greenhouse for plug production. Resulting plugs were transplanted in a 30’x96’x8' high tunnel. Six raised beds were made, and three of them were assigned randomly for low tunnel installation. The experiment was conducted as a completely randomized design. The treatment design was a split-plot design, with low tunnels/control (without low tunnels) as main plots and cultivars as split plot. There are 40 plants in each split plot. Low tunnels were installed on November 23, 2015. There were no interactions between low tunnel and cultivar treatments. Preliminary results indicated that there were no significant differences between the low tunnel and control treatment in terms of the first harvest date, marketable yield, total yield and cold damage to open blossoms. However, the numerical values constantly favored the low tunnel treatment. For example, the total yield and marketable yield were 2.99 and 2.84 kg/rep in the low tunnel treatment, compared to 2.27 and 2.15 kg/rep in the control. Low tunnel also advanced the first harvest by five days. There were significant differences between cultivars on the date of first harvest and flower damage. ‘Radiance’ and ‘San Andrea’ were harvested 10 days earlier than ‘Abion’ and ‘Winterstar’; “Radiance’ had most severe flower damage (74.6% on 24 Feb. and 40.7% on 28 Jan.) while ‘San Andrea” had the least (47.8% and 23.8%, respectively). Microclimate factors such as low air temperature, soil temperature and solar radiation were measured with Spectrum® data loggers and sensors every 30 minutes. Data suggested additional protections would be provided by the low tunnels. The ins-and-outs of including low tunnels in high tunnels on winter production of strawberries in terms of winter and spring production, plant growth, and pest challenges will be discussed.