Evaluating the exclusion and non-target effects of shade netting on apple orchards

Project Overview

Project Type: Graduate Student
Funds awarded in 2017: $23,678.00
Projected End Date: 11/30/2018
Grant Recipient: Washington State University
Region: Western
State: Washington
Graduate Student:
Principal Investigator:
Dr. Elizabeth Beers
Washington State University


  • Fruits: apples, general tree fruits


  • Pest Management: integrated pest management, physical control

    Proposal abstract:

    With apple orchards shift towards high density production, sun-burn has become a major threat to fruit quality and cosmetic appearance. Growers have tried many tactics to reduce sunburn, ranging from sprayed sunscreens to overhead misting systems. Recently, newer orchards are being equipped with shade netting structures to reduce direct sunlight. While helping to prevent sun damage, these netting structures could also be effective barriers to invasive pests such as the brown marmorated stink bug (BMSB) (Halyomorpha halys, Stål). Since its introduction into the United States, this pest has caused catastrophic losses to mid-Atlantic apple growers, and insecticides have not proven to be very useful. Although nets may successfully exclude BMSB, they could disrupt biological control by preventing natural enemies from entering the orchards. Successful implementation of netting could ensure long lasting and highly productive orchards, especially if shade netting can be used to prevent BMSB from establishing. We aim to answer this question with ­­­three main objectives: 1) Determine the effectiveness of different shade net structures in excluding stink bugs; 2) Quantify the effects of netting on natural enemies and secondary pests of apple orchards; 3) Inform growers and the public on the role of netting in sustainable orchard systems. We will accomplish these objectives by collaborating with two apple orchardists in central Washington and utilizing two experimental apple plots provided by the WSU Tree Fruit Research Extension Center. In each research block, scaled-down replicas of commercial netting structures will be installed; 16 cages were already built in 2015 in the experimental apple plots. In the private plots, barriers at the interface of the natural habitat and the orchard will be constructed. Using captured E. conspersus, since BMSB has not established yet, we will conduct mark and recapture studies to determine the cages exclusion abilities. Coinciding with this will be weekly sampling experiments, which will quantify the nettings effects on resident pests and their natural enemies. Along with these experiments there will be an elaborate outreach program promoting cooperation with current researchers, local orchardists, and public organizations. We will send updates of our findings to the nationally recognized StopBMSB.org website, in addition to updating the WSU TFREC website (treefruit.wsu.edu) with current information on netting and stink bugs. Furthermore, we will distribute brochures on how to identify the invasive stink bug and information on the new, environmentally sustainable, netting in orchards.

    Project objectives from proposal:

    Objective 1: Determine different shade net structures effectiveness at excluding stink bugs.

    Objective 2: Examine the effects of shade netting on resident pest and natural enemies in apple orchards.

          (i). Sub-Objective 2a: Monitor resident pest and natural enemy densities inside and outside the cages.

          (ii). Sub-Objective 2b: Measure ambient air temperature and humidity inside and outside the cages.   

          (iii). Sub-Objective 2c: Conduct choice and no-choice tests with netting material on parasitoids.

    Objective 3: Inform growers and the community of the effects of netting in orchards.

          (i). Sub-Objective 3a: Create online media focused on BMSB and netting implementation in orchards.

          (ii). Sub-Objective 3b: Update the WSU website and StopBMSB.org with our current research and findings.

          (iii). Sub-Objective 3c: Develop and distribute brochures on BMSB and shade netting at the community center and local environmental agencies.  


    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.