High tunnel.

2016-17 Rapid Ag: Canopy Management and High Tunnel use for Maximizing Control of Spotted Wing Drosophila in Raspberry

April 15, 2016

Principle Leader

Bill Hutchison

Department

Department of Entomology

Funding Awarded

  • 2016 Fiscal Year: $76,100
  • 2017 Fiscal Year: $73,372

The Problem

With Minnesota’s raspberry, strawberry, grape, and blueberry crops representing a combined ~ $9.9 million at risk and an additional ~$25 million estimated at risk in the high tunnel sector of the fruit growing industry, it is imperative that we improve our understanding of how to manage Spotted Wing Drosophila (SWD) with current control options while new options are developed and investigated. These results will be used to generate integrated pest management (IPM) solutions. 

Background

Since the 2012 detection of the invasive Spotted Wing Drosophila (SWD), Drosophila suzukii, in Minnesota, considerable effort has focused on documenting the timing of first arrivals and population peaks, as well as monitoring practices to detect and warn growers of a pending risk for fruit infestation (Asplen et al. 2015).  Although progress has been made, little attention has been given to options for managing this pest once it has been detected in fruit crops. As an invasive fruit pest in North America since 2008, several publications from other states have focused on insecticide efficacy but have mostly been limited to laboratory trials or field trials that demonstrate adult efficacy only (Bruck et al. 2011); some are “semi-field” studies where fruit and/or tissue is sprayed in the field but then infested with adult SWD in the lab (Van Timmeren and Isaacs 2013).  Few published trials have combined results for adult efficacy of insecticides and subsequent fruit infestation levels to provide growers with the management information necessary for on-farm use.

Most agricultural pest species are managed via control of the life stage feeding on a specific crop (e.g., caterpillars feeding on foliage) and insecticide applications are targeted at these life stages with residues providing control through ingestion or contact.  For SWD, management of the adult life stage is necessary to prevent egg lay and larval presence inside the fruit.  SWD uses its serrated saw-like ovipositor (Fig. 1a) to penetrate the skins of soft fruits such as raspberries, blueberries and grapes.  Eggs that have been laid inside the berry hatch and larvae feed inside the berry causing severe damage and eventual collapse of the infested fruit (Fig. 1b). This feeding damage will typically lead to secondary bacterial and fungal infections.  Raspberries are the most susceptible and at-risk fruit crop in Minnesota with infestation levels easily reaching 80% in the absence of control measures and may exceed 60% even with seven insecticide applications (Rogers et al. 2015). 

Objectives

  1.  Evaluate the impact of row width and trellising to improve canopy coverage of foliar insecticides and efficacy against SWD using conventional insecticide sprays on fall bearing raspberry.
  2.  Evaluate production of fall bearing raspberries under plastic covered high tunnels for management of SWD and the influence of traps on SWD populations under the covered tunnels.
  3.  On-farm comparison of plastic covered high tunnels with and without insecticide use for control of SWD population and fruit infestation in raspberries.