2014 ASHS Annual Conference

At the University of Arkansas Research and Extension Center in Fayetteville, strawberries are grown under high tunnels to provide a protected environment that allows for harvest in the off-season.  The high tunnel system protects berries from frost and other weather related conditions that limit the season for berries grown outdoors.  For the three years prior to the 2013/2014 season, this high tunnel production system has produced strawberries from late November through April. 

During the 2013/2014 season, intermittent extreme cold events beginning in early December and continuing into March have challenged this extended season production system. Typical planting time for extended season high tunnel strawberry plugs is early September for production beginning in November and continuing into May.  In December of 2013 when the first extreme cold event occurred, the high tunnel strawberry plants, were beginning to bloom and set fruit. To reduce the amount of damage to plants, the high tunnel strawberry plants were covered with three protective layers – 3ml row cover, loose straw, and recycled high tunnel plastic. Weather data was collected for both outside and high tunnel strawberry plantings.  This data showed that during the first December cold snap, the temperature dropped to -14°C outside, but only reached -1°C under the snow-covered row covers of the field planting. Weather data collected inside the high tunnels showed the low was -11°F at 4’ above the ground and 6°C at the plant canopy under the protective covering.

In late January, 2014 Fayetteville, AR experienced another extreme cold episode with winds gusting between 40 and 60 miles per hour.  During this episode, one of the high tunnels sustained some damage on the north end-wall causing the protective covering to be blown off a portion of the berry plants.  The temperature outside and inside the tunnel was -8°C when the problem with the end-wall was discovered.  An assessment of the damage showed that the berries and many of the flowers were damaged.  However, a crown assessment indicated not damage to the crowns.  Overall, compared to previous years arthropod management was reduced whereas there was more need for disease management. No fruit was harvested during this time.

This extremely cold winter has provided many insights into high tunnel strawberry temperature thresholds, as well as the type and timing of weather protection required for survival of high tunnel strawberry plants during extreme cold episodes.