Michigan spotted wing Drosophila report for July 14, 2015

The summer increase of spotted wing Drosophila has begun in southern Michigan.

This is the fifth weekly report of the Michigan State University Extension spotted wing Drosophila (SWD) monitoring network. The summer increase of SWD has begun across southern Michigan (see graph). Sixty-eight females and 74 males for a total of 142 were captured from 23 traps out of the more than 130 traps being monitored as part of the network. This is a tenfold increase from the 15 total SWD captured last week. Ripening thin-skinned fruit such as blueberries, raspberries and cherries are the most vulnerable to infestation. Additionally, berries produced by a number of wild fruiting trees and shrubs such as black raspberries, honeysuckle and mulberries can be infested. Growers and scouts should be on their guard with susceptible fruit crops beginning to ripen.

Spotted Wing Drosophila catches
Average number of spotted wing Drosophila flies caught in traps in four Michigan fruit production regions. NW represents 67 traps in Antrim, Benzie, Grand Traverse, Leelanau, and Manistee Counties. SE represents 12 traps across Genesee, Ingham, Lapeer, Lenawee, Livingston, Macomb, Monroe, and Oakland. SW represents 35 traps across Allegan, Berrien, Kalamazoo, Ottawa, and Van Buren. WC represents 12 traps in Ionia, Kent, Mecosta, and Oceana.

Trap location has a big effect on the number of SWD captured, so these following statements are for guidance only. Trapping in your own fields is the best way to know what’s happening on your farm. Two counties in southeast Michigan were tied this week for the highest per trap catch with 20 flies per trap found in both a Macomb County sweet cherry orchard and an Oakland County raspberry planting. Otherwise, SWD were also caught in traps placed next to Berrien County strawberry, tart cherry, raspberry and blueberry plantings; Van Buren County plum and tart cherry orchards; Allegan and Ottawa County blueberry plantings; Kalamazoo County blackberry; Antrim County wild mulberry next to a commercial tart cherry orchard; Kent County sweet cherry; Ingham County grape; Monroe and Lenawee County tart cherry; Livingston County tart and sweet cherry; and Macomb County sweet cherry.

Traps in the network are baited with Trece lures and placed near susceptible crops and wild hosts in each of the major fruit growing regions across the state. Commercial plantings include strawberries, blueberries, raspberries, grapes, tart and 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.

Additional trap networks in the state that are baited with other lures including a yeast-sugar mix are also trapping SWD flies, often in higher numbers than the Trece lures. This just reiterates the importance of protecting fruit that is in the ripening or ripe stage as the SWD population is clearly on the upswing.

For instructions on how to construct your own traps and use them for monitoring for SWD, please visit the MSU Spotted Wing Drosophila website. For specific recommendations about managing SWD in berry crops, please see “Increase of spotted wing Drosophila in berry crops.”

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