Spotted wing drosophila attacks fruit

Posted June 26, 2014 at 10:07 am

by Marilyn Odneal, Horticulture Adviser

Last year we found spotted wing drosophila (SWD) at the State Fruit Experiment Station at Mountain Grove for the first time.

This pest is a major problem for small fruit growers, particularly those who grow blueberries, blackberries or raspberries. Strawberries, cherries, grapes and other soft-skinned fruits are also susceptible. SWD looks like a vinegar fly that we find around ripe fruit – or vinegar. The problem with the spotted wing drosophila is, unlike the common fruit fly, it does not wait until the fruit is overripe or already rotting. The SWD attacks sound, ripe fruit. The female cuts a slit in the thin skin of the berry to lay eggs. The eggs hatch into small whitish worm-like larvae that infest the fruit. Damaged fruit will rot.

To make matters worse, the spotted wing drosophila has a lot of other hosts on which to feast. These include wild blackberries and raspberries, elderberry, pokeweed, autumn olive, honeysuckle, yew and buckthorn. It is difficult to control SWD since it has so many generations per year.

In response to this new threat in Missouri, Lincoln University created a new IPM BLOG with emphasis on spotted wing drosophila. The goal of this IPM blog is to provide relevant and timely local/regional information about this invasive pest that can be used by farmers and gardeners to protect their crops.

Go to http://www.LU-IPM.net to access the most recent information about SWD in Missouri and in the Midwest. At this site you will find information on how to trap and identify this pest. If you find out that you have SWD, you will also find what insecticides are available to use against it.

On June 8, Dr. Jaime Pinero, state IPM specialist, issued an alert that SWD has already been found in monitoring traps in SW MO (Webb City area). So keep an eye out, since awareness of any new problem is the first step in managing it. If you grow any small fruit crops, watch for rots, larvae and SWD flies. If you need help identifying flies in a trap, contact Dr. Jaime Pinero (573-681-5522) or Jacob Wilson (573-681-5591) at the Lincoln University IPM Program.

The trap to catch spotted wing drosophila is a plastic container baited with 1⁄2 tablespoon active dry yeast plus 2 Tablespoons sugar plus 6 ounces of water. A yellow sticky board is suspended above the bait to trap the flies. The traps are set in the shaded foliage and are inspected weekly at which time the bait is replaced.

Direct comments or questions concerning this column to Marilyn Odneal via email at MarilynOdneal@missouristate.edu; write to Missouri State Fruit Experiment Station, 9740 Red Spring Road, Mountain Grove, Mo. 65711; or call (417) 547-7500. Visit our website at http://mtngrv.missouristate.edu.