Small Fruit Production in High Tunnels

High tunnels are a relatively economical form of protected culture, and offer cultural advantages such as protection from the elements and an extended production season. Interest in high tunnels for small fruit production has been increasing in North America. Growers in the United States and Canada are using multi-bay and single-bay high tunnels for production of red raspberry ( Rubus idaeus ), black raspberry ( Rubus occidentalis ), blackberry ( Rubus subgenus Rubus ), strawberry ( Fragaria × ananassa ), and blueberry ( Vaccinium spp.). Research trials using high tunnels are being conducted in numerous places across the United States. In most instances, high tunnels increased yields of berry crops, improved quality, and decreased the incidence of most diseases compared with field production, powdery mildew ( Sphaerotheca macularis ) being a notable exception. The insect and mite complex encountered in tunnels when growing berry crops has changed markedly, often becoming similar to that which might have been expected in greenhouses, with numbers of two-spotted spider mite ( Tetranychus urticae ), whitefly (Aleyrodidae), and thrips ( Frankliniella spp.) reaching high levels without control measures. In studies at The Pennsylvania State University, primocane-bearing cultivars of red raspberry plants produced at least two to three times as much marketable fruit in tunnels as in a previous field study, with substantial summer and fall crops obtained. ‘Triple Crown’ thornless blackberry produced very high marketable yields in the tunnels, even though winter injury historically resulted in a lack of blackberry production in the field. Strawberry production in a plasticulture system using short-day or day-neutral cultivars was found to be viable; however, the primary benefit of high tunnels for strawberry may have been reliability of production rather than a yield increase. Potential reasons for improvements in productivity and quality are numerous and warrant further attention.