Michigan spotted wing Drosophila update – July 5, 2019

With warmer weather, more spotted wing Drosophila were trapped this week; protect susceptible crops.

In our June 26 spotted wing Drosophila (SWD) update, we urged growers to monitor for SWD locally and to begin protecting susceptible fruit, including ripening cherries, summer raspberries and strawberries. During the week of June 30, we saw an increase in the number of SWD caught in the Michigan State University Extension SWD trapping network. Out of the 19 counties and 80 sites being monitored by MSU Extension, we caught SWD at about 20% of the sites that reported catches, with an average of 1.0 SWD flies per trap in the past week. This is a low number, but it is about double from the week before, and all of the increase was from captures of more female SWD.

Given how quickly this pest can reproduce and how devastating infestation can be, if your crop is at a susceptible stage and you have begun to catch SWD in traps being monitored on your farm, apply a cover spray of an insecticide that is rated excellent against this pest to protect fruit and maintain populations at current low levels. Remember to rotate insecticide classes once you begin your spray program. You can determine how well your program is working by trapping for flies and sampling fruit using the salt test in the days prior to harvest.

We have also trapped the first blueberry maggot flies in monitoring traps at unmanaged farms in Van Buren County, which lines up closely with the predictions from our fruit fly monitoring model, which shows expected first emergence in early July across southwest Michigan.

Check out the most recent versions of SWD management guides offered by MSU Extension.

Refresh your ability to identify SWD with MSU Extension’s Spotted Wing Drosophila Identification Guide.

For more information on effective insecticides registered for use to control SWD, refer to MSU Extension’s Michigan Fruit Management Guide for 2019 (E-154).

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