Insights into SWD from North Carolina and Michigan

In December I had a conference call with Dr. Hannah Burrack (North Carolina State University), Dr. Rufus Isaacs (Michigan State University), and Dr. Blair Sampson (USDA-ARS, Poplarville, MS).  Seeing as our knowledge of Spotted Wing Drosophila (SWD) here in Mississippi is limited, I wanted to glean as much information from these experts as possible.  Dr. Burrack is an Assistant Professor of Entomology and Extension Specialist.  Her specialty is Applied Insect Ecology and Pest Management in Field and Horticultural Crops.  She has an excellent blog with great information on SWD and other pests.  You can access it here:

Dr. Isaacs is a Professor of Entomology and his specialty is insect ecology and behavior to develop insect management practices for sustainable crop production, with a focus in berry crop systems including grape and blueberry.  Michigan State maintains a blueberry website that can be access here: Recommendations for control from MSU can be found here:

Dr. Sampson is a Research Entomologist with USDA-ARS at the Thad Cochran Southern Horticultural Laboratory in Poplarville, MS.  His ares of specialty are integrated pest management and crop pollination. What follows are some tidbits about SWD that I was able to write down from our conversation.

  • The pest cannot be eliminated, just reduced (managed)
  • Reducing populations may reduce egg laying
  • A strong management program will help in blueberries
  • SWD infestation and flight activity decrease when temperatures are very hot, 90+F
  • A good spray program can hold the pest in check, but environmental factors such as rainfall can hinder efficacy
  • SWD populations increase later in the growing season
  • Fruit should be kept cool after harvest, as SWD eggs/larvae do not develop at cold temperatures
  • The fruit needs to be sprayed at the beginning of the susceptible phase (could be as early as green fruit stage)
  • Blueberry growers in NC seeing Southern Highbush escape SWD because of their earliness and Rabbiteyes account for the main losses
  • Spray technology options include tower sprayers, helicopter, airplane, cannon sprayers
  • Spraying bordering wooded land may be an helpful management strategy
  • Conventional protection products include Mustang Max, Malathion, Delegate, etc.
  • Broad spectrum products may increase likelihood of secondary pests, e.g. spider mites
  • IMPORTANT— check with marketer before spraying anything to find out which products are acceptable and unacceptable
  • Some products have restrictions that may limit their use for You-Pick operations
  • SWD may not be as devastating in You-Pick because bad berries can be picked around or bad berries can be removed prior to opening
  • In North Carolina, infestation rates are much higher in blackberries than blueberries — 100% vs 10-15%
  • In NC, blackberries are being treated 2 times per week, rotating 3 materials, spraying on ripening fruit
  • Infestations are found in high tunnels, but infestation rates may be lower
  • Control of SWD in high tunnels may be better because sprays last longer

2 thoughts on “Insights into SWD from North Carolina and Michigan

  1. Is there in color that atrracts these insects i.e. blue yellow? Or even certain plants that they won’t go around? I am so far a chemical free farmer and use sticky traps and tapes as well as certain plants to control the insect problems.

    • Robert:
      We still have a lot to learn about this fly. It will be difficult to control without spraying something if you have it in your berries. There are some organic spray options.

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