Evaluating Low Tunnel Plastics for Day-Neutral Strawberry (Fragaria ×ananassa Duchesne) Production in Minnesota

Abstract

American consumers place high value on local agriculture and direct market sales, particularly for fruits and vegetables. Growers who supply local strawberries, especially organic, have a competitive edge in the direct-to-consumer market. New developments in extended season strawberry production offer new opportunities for growers in the Upper Midwest to meet this demand for local, organic strawberries using low tunnel protective structures in an annual day-neutral strawberry production system. A range of specialty tunnel plastics that modify the light around plants are now available as well, but there is little information on how these products influence strawberry growth and performance in the field. We tested the effects of experimental UV-blocking and UV-transmitting plastics on light and microclimate in low tunnel environments and on fruit yield and fruit quality in the day-neutral strawberry ‘Albion’. We also assessed changes in UV transmittance levels of the plastics over time and evaluated their use in the context of organic insect pest management. We collected data on the presence of the insect pest species Lygus lineolaris (tarnished plant bug) and Tetranychus urticae (two-spotted spider mite) in the field and tested the effectiveness of the microbial-based organic biopesticides Entrust SC (AI: spinosad), Mycotrol WPO (AI: Beauveria bassiana), and PFR-97 (AI: Isaria fumosorosea) for control of Drosophila suzukii (spotted wing drosophila) in semi-field bioassays. This research was conducted on USDA-certified organic land at the Minnesota Agricultural Experiment Station (MAES) in St. Paul, Minnesota in the 2016 and 2017 growing seasons. We found that both UV-transmitting and UV-blocking plastics improved fruit yield and quality compared to an open control, and the plastics maintained their spectral properties over the course of one season. There were no distinct differences in results observed between the UV-transmitting and UV-blocking treatments. Covering type did not affect the presence of L. lineolaris or T. urticae in the field, nor did it influence the efficacy of the biopesticides for control of D. suzukii in semi-field bioassays.