The use of insect netting on existing bird netting support systems to exclude spotted-wing Drosophila from a mature small-scale commercial highbush blueberry planting

Project Overview

Project Type: Farmer
Funds awarded in 2014: $11,820.00
Projected End Date: 12/31/2016
Region: Northeast
State: New York
Project Leader:
Dale Ila Riggs
The Berry Patch of Stone Wall Hill Farm, LLC

Annual Reports


  • Fruits: berries (other), berries (blueberries)


  • Crop Production: application rate management
  • Education and Training: demonstration, farmer to farmer, on-farm/ranch research, participatory research
  • Pest Management: cultural control, field monitoring/scouting, prevention
  • Production Systems: organic agriculture
  • Sustainable Communities: quality of life

    Proposal summary:

    Spotted Wing Drosophila (SWD) is an invasive species, native to Asia, that was recently introduced in the US. First detected in California in 2008, it has established itself throughout the U.S. It was found in NYS in the fall of 2011, and caused an estimated $3 million loss in berry crops in NYS in 2012. I had a 40% loss in my blueberries in 2012. I had a 25% loss in my fall raspberries, since I sprayed them every 3-4 days after discovering SWD. The biggest problem with SWD is that by the time you know it is on your farm, it is virtually too late to control it. It lays its eggs in fruit that are just starting to ripen, and it matures so quickly that when ripe fruit is picked it is contaminated with maggots. Reliable traps have not yet been developed, so growers throughout the country have had to abandon IPM principles of monitoring and treating at a given threshold. All insecticide treatments are aimed at preventing SWD populations from infesting the crop. Organic, no spray, and small scale berry growers are at a distinct disadvantage when trying to control this pest. Only one organically approved insecticide has shown efficacy, and it can only be applied twice before having to rotate to a different class of insecticides, none of which have been effective at controlling SWD.

    Many growers have traditionally been able to grow blueberries in the Northeast without spraying them and have no interest in spraying. And small scale growers with mature plantings like myself do not have the ability to get tractor mounted equipment down between rows to ensure adequate coverage. In 2013, I purchased a gasoline powered backpack sprayer to better apply pesticide in the planting. However, when the 4 gallon spray tank is filled, the sprayer weighs 60 pounds, difficult for small statured farmers or older backs to handle. I used a battery-operated sprayer to control SWD in 2013. To ensure adequate coverage, not spray when pickers were in the field, or when windy, I could only spray one quadrant per night, thus it took 4 nights in a row to cover my half-acre planting. When the suggested spray schedule is a 5-day schedule, and one must reapply after a rainstorm, it is quickly evident that spraying for SWD is not a long-term viable option for small scale and organic blueberry growers. Due to the lack of knowledge concerning how to manage this insect, the number of farmers that do not have the equipment nor desire to spray, and until viable bio-control options are available (not soon), excluding this insect is the only control option available to small scale, no spray, low spray and organic blueberry growers. I propose to test .95mm x .95mm (80 gram) insect netting on two different existing bird netting support systems to exclude SWD from a mature planting of blueberries that are harvested from mid-July to early September.

    Spotted Wing Drosophila (SWD) is an invasive fruit fly that threatens the viability of small scale, organic, and no spray berry farms. Found in the Northeast in 2011, in 2012 it caused losses of 80 – 100% of fall raspberries and 30 – 50% of blueberries. SWD lays its eggs in unripe fruit, resulting in maggots contaminating ripe fruit. Control must be aimed at preventing egg laying, so IPM practices of using thresholds have been abandoned. One organically approved pesticide is effective against SWD and only two applications can be made before it must be rotated with other pesticides, none of which have been effective. Additionally, there are significant numbers of growers who do not want to spray. Small scale trials with insect netting have shown promise for excluding this pest from plantings but there have not been any trials looking at systems that will allow a grower to cover their crop, yet still harvest efficiently, in comfortable conditions, without allowing SWD in during the process.

    This farmer has two existing bird netting support systems that she wants to adapt to support large sections of insect netting showing promise in small scale trials. The trial will document the steps and costs involved in adapting the support systems, the return in increased berry marketability, and will evaluate SWD infestation levels through trapping and fruit evaluations. This demonstration will enable growers to view first hand, or learn through conferences and written articles, the potential for using exclusion as a way to manage SWD.

    Project objectives from proposal:

    The objective of this project is to adapt an existing bird netting support system to support large expanses of insect netting to exclude SWD from mature highbush blueberries. A second objective is to determine how effective the netting is for preventing SWD from infesting blueberries at a commercially acceptable level throughout a long harvest season. ProtekNet 80 gram insect netting (.95mmx .95 mm) will be purchased from Dubois Agrinovation in Saint-Remi Quebec. One of the current problems with existing insect netting is that it is not available in wide widths to cover large areas. Dubois can have pieces of their 80 gram netting sewn together to create a 26 foot wide piece but larger pieces cannot be created – they are just too large for existing machinery to handle.

    We will take two 26 foot wide pieces of the netting and combine them by rolling them around pvc pipe and then fastening them with existing greenhouse hardware that is used to attach roll up sides to purlins on greenhouses – see photo 1. PVC pipe and hardware will be provided by The Berry Patch. By fastening these two pieces together we will have an approximately 51 foot wide sheet of insect netting to apply on the entire length of the planting (250 feet).

    I propose to test the efficacy of this netting in excluding SWD using two different support systems described below. One system is made of tall metal poles with PVC tees on the top of each post to facilitate movement of netting over and along the height of the posts.  A 51 foot wide piece of insect netting will cover three rows of blueberries, while still leaving enough on the bottom to anchor. The other system is made of greenhouse hoops, set further apart within the rows. See photo 3.

    The greenhouse hoop system worked extremely well for us with bird netting, and I suspect it will work equally well with insect netting, if not better. Two sets of bows, placed right beside each other, will allow me to rest the pvc pipe holding the seam of the insect netting in the valley between the two sets of hoops. This system will allow me to cover 3 rows of blueberries with one set of insect netting. Galvanized pipe, used as purlins in greenhouse construction will be used with the same greenhouse parts fasteners as in photo 1 to attach the insect netting at the ground level. The galvanized pipe is preferred due to its heavier weight and therefore, greater likelihood of weighting down the insect netting to prevent infestations from SWD getting in under the netting along the edges. 

    An entrance vestibule will be built for each of the two covered treatments, consisting of approximately a 4’x 4’x7’high area that will be attached to a “doorframe” of 4 x 4’s in the end of the netting. The vestibules will be anchored to the ground with 3 foot long pieces of rebar, and attached to the doorframe in the netting with hinged latches so that they can be removed when netting is not needed and stored under cover in a barn. The vestibule will also be covered with ProtekNet 80 netting. A vertical slit will be cut in the end of the insect netting in the middle of the doorframe entrance to the field, and a sheet of insect mesh will be attached to the top of the doorframe on the outside of the netting. This will provide multi layers of protection from SWD being able to infest the planting.

    To perhaps visualize the entrance, one should visualize a walk in cooler that has the plastic strips inside a doorway to prevent cold loss. Workers will need to enter the vestibule, close the outside door of the vestibule, and then enter the planting itself by moving the curtain of netting to the side and stepping through the slit netting into the planting. The netting will be put up as the first variety of berries starts to show color, usually during the first week of July.

    There will be three treatments.
    Treatment one is netting applied over upright posts to cover 3 rows of blueberries.
    Treatment two is netting applied over greenhouse hoops to cover 3 rows of plants.
    Treatment three is an uncovered control (covered with bird netting only) that will be sprayed with Entrust or Delegate insecticide, rotated with appropriate effective materials for purposes of resistance management.

    To measure the efficacy of the system, SWD traps consisting of an ampule filled with a fermenting solution of yeast, sugar, water, and whole wheat flour with a killing solution of apple cider vinegar, raspberry juice, and soap will be set in each treatment. On the recommendation of Dr. Greg Loeb, Professor of Entomology at the NYS Experiment Station, 2 traps will be placed in the front edge of each treatment and 2 traps in the back edge of each treatment. These traps will be checked weekly, solutions changed, trap contents recorded and charted over time. 90 ripe fruit per treatment will also be harvested weekly and examined visually for oviposition scars. Fruit will be collected systematically from the three rows distributed in each covered treatment. In the netted rows, each border row and the middle row will be sampled. In the control row, both rows will be used for fruit sampling. After visual inspection fruit will be put into salt water to confirm the presence or absence of larvae following well-established procedures. Twice during the season, once in the early part of known SWD presence (SWD in adjacent hedgerow traps) and once in the late season, fruit will be collected and sent to Dr. Loeb’s lab and reared out to confirm the presence or absence of SWD, and density of infestation.

    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.