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The Rolla Daily News - Rolla, MO
  • Gardening to Distraction: New berry bad fruit fly

  • Wouldn’t you know it, the year I plant a dozen blackberries, raspberries and elderberries, there is a new invasive fruit fly destroying their fruit.
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  • Wouldn’t you know it, the year I plant a dozen blackberries, raspberries and elderberries, there is a new invasive fruit fly destroying their fruit.
    Spotted Wing Drosophila was first detected in Missouri in summer 2013. By fall 2013, the tiny fly similar to other vinegar flies was reported infesting crops statewide.
    According to Jacob Wilson, with the Lincoln University Extension integrated pest management program in Jefferson City, this new invasive fly will affect small fruit crops — in particular, raspberries, blackberries, blueberries, elderberries and grapes.
    Stone fruits, such as cherries, nectarines, peaches, peppers, as well as high tunnel tomatoes and wild plants such as pokeweed, autumn olive, crabapple, nightshade, Amur honeysuckle and wild grapes may also be impacted.
    Originally from eastern Asia, the invasive insect differs from established fruit flies by having a serrated organ the fly can use to cut through fruit skins. After making the cut, females lay eggs. Larvae hatch and feed inside fruit, causing them to rot.
    This insect reproduces quickly. A few adults can become millions of flies in a few months.
    Wilson said because this pest is so new to Missouri, there has been no research on insecticidal treatments to manage Spotted Wing Drosophila.
    Other states, such as Michigan and Oregon, have had the pest for years so treatment methods are based on their recommendations.
    Wilson said one of the telltale signs of this invasive fruit fly is mushy fruit.
    “You may think you picked it over-ripe but it may also be that Spotting Wing Drosophila has planted larvae and they are destroying the fruit from inside,” Wilson said.
    One of the ways to confirm Spotted Wing Drosophila larvae is to soak fruit in sugar water. Place fruit in a plastic bag and crush lightly to break skin. Add four cups of water to every one-fourth cup of sugar. Fruit sinks to the bottom, fly larvae float to the top. You may need a magnifying lens to spot the tiny larvae.
    To detect these miniscule flies on still hanging fruit, Wilson said to use plastic cups with a sticky yellow insert to hang over berry areas. The idea is to monitor how many flies are caught in the trap to determine if they are even present and how many are in an area.
    Wilson said only a few will show up at the beginning of the season. By mid to late summer, as they continue to lay eggs in fruit, detectable numbers should increase.
    In brambles, using a trellising system that opens the canopy will help discourage these new flies. Thinning the plant row to three to four strong canes per square foot potentially may make the plantings less attractive.
    Repair leaky irrigation systems and water from the ground, not overhead. Allow ground and mulch to dry before watering.
    Page 2 of 2 - To minimize increasing fly populations, remove over-ripe fruit from plants and pick it up from the ground. Any available fruit may become host to egg-laying and larval development.
    To make a trap, use a clear plastic cup with a fitted lid with several 3/16-inch melted holes using a soldering iron on the sides. Bait with a mixture of six ounces of water, one-half tablespoon of dry active yeast and two tablespoons sugar. Add a small yellow sticky card that fits the diameter of the container hanging in the middle available for purchase from Morgan County Seeds or Hummert International.
    Place traps inside the vegetation in shade. Another trap located in adjacent woods may also provide early detection.
    For small acreage and high tunnel, use one trap for plots up to one acre. For larger farms, use a minimum of three traps per five acres.
    For more information, contact Wilson at WilsonJ@LincolnU.edu or call 573-681-5591. Here is a link for more information online: http://ipm.missouri.edu/MEG/2013/8/Detecting-larval-infestations-and-insecticidal-options-for-Spotted-Wing-Drosophila-a-significant-pest-of-small-fruit-crops-in-Missouri/Detecting_larval_infestations_in_fruits_and_insecticidal_options_forSWD.pdf.
    Charlotte Ekker Wiggins is a certified gardener sharing gardening tips in a changing climate. Copyright 2014 used with permission by Rolla Daily News, Waynesville Daily Guide and River Hills Traveler. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Contact Charlotte at chargardens@ gmail.com.

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