Michigan spotted wing Drosophila report for June 23, 2015

Trap catches are low to zero across Michigan; a few more southwest sites are reporting first catches this week.

Last week, the Michigan State University Extension spotted wing Drosophila (SWD) monitoring network detected the first SWD in traps baited with commercial lures in Berrien and Benzie counties and urged growers and their scouts to set up traps near susceptible crops. This week, no SWD were caught in northwest Michigan traps, but four females and one male were caught from three traps in Berrien County. These traps were baited with Trece lures and placed near tart cherry, strawberry and blueberry plantings. There were also a couple of reports this week of SWD females, one per trap, caught in two traps in Allegan County placed in blueberries and raspberries; one trap was baited with a sugar/yeast solution and the other was baited with a Scentry lure.

The remainder of the more than 100 traps in the monitoring network caught no SWD this past week. Traps are set up in each of the major fruit growing regions across the state in all of the susceptible crops grown in Michigan as well as in tree lines and woodland edges that contain wild hosts. Commercial plantings include strawberries, blueberries, raspberries, grapes, tart cherries, sweet cherries, peaches and plums. Wild hosts in the trapping network include autumn olives, black cherries, pin cherries, choke cherries, blackberries, honeysuckle, mulberries and wild grapes.

Adding borax to drowning solution in traps helps preserve SWD

Last week, we posted detailed instructions for making your own traps and how to deploy them. We have one refinement to suggest, which is to add borax to the drowning solution (i.e., unscented soapy water) at a rate of 38 grams per gallon. Adding borax helps prevent mold growth between trap checks and better preserves the specimens caught in traps, and in particular, preserves key features that can be obscured by the growth of mold in the drowning solution.

For more information about monitoring and management of SWD in Michigan fruit crops, please visit the MSU Spotted Wing Drosophila website.

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