ECOLOGY AND MANAGEMENT OF PESTS ON LOW TUNNEL STRAWBERRY

Abstract

Growing strawberries under protective low tunnels is becoming increasingly popular among growers in the northeastern U.S. due to benefits of season extension and crop protection. However, it is currently unclear how this new system impacts the presence of pests and beneficial invertebrates, and options for pest management. The first two chapters of this dissertation summarize projects that compared the presence of pests (weeds, pathogens, and invertebrates) and beneficial arthropods (predators, pollinators and parasitoids) on strawberry grown under low tunnels vs. the open-field. We conclude that low tunnels benefit strawberry production by improving yield and protecting against fruit and foliar pathogens while having minimal impact on services provided by beneficial predators, parasitoids and pollinators. However, tunnels are likely to support higher densities of Tetranychus urticae and offer no protection against the most economically important pest identified, Lygus lineolaris. Chapter 3 describes how biocontrol efficacy against L. lineolaris using the microbial pathogen Beauveria bassiana can be improved using low tunnel coverings that block UVB radiation. To develop an integrated management plan for T. urticae under low tunnels, we evaluated host plant resistance (Chapter 4) and biological control (Chapter 5) tactics. We identified several cultivars that are susceptible to T. urticae, and associated susceptibility with small plant size. When comparing biocontrol efficacy of two commercially available predatory mites Phytoseiulus persimilis and Neoseiulus fallacis against T. urticae, we found that both species (released singly or together) can manage T. urticae in greenhouse systems. In the field we observed low retention by P. persimilis, even when multiple releases were made, and therefore suggest that N. fallacis may be a better candidate for biocontrol on low tunnel strawberry. Chapter 6 focuses on describing the dispersal behavior of N. fallacis and P. persimilis and how rearing practices may influence dispersal and biocontrol efficacy of these important predators. Phytoseiulus persimilis was a more active disperser compared to N. fallacis, and dispersal for both species was often higher for those reared on strawberry compared to standard bean plants. Disperal was also higher when predators were released onto bean plants, regardless of rearing host plant. The implications for how dispersal behavior can be manipulated to improve biocontrol are discussed. The objective of this reseach was to address knowledge gaps in low tunnel strawberry management, specifically how tunnels impact the presence of pests, beneficials and options for pest management that can be used to build an IPM framework for this system as it expands in the Northeast.