Northwest Michigan fruit regional report – August 12, 2014

The average number of spotted wing Drosophila captured in the northwest region has been slowly increasing since the first detection at the end of June.

In cherries, cherry fruit fly numbers continue to remain consistently low at the Northwest Michigan Horticulture Research Station with a total of two flies captured this week. Spotted wing Drosophila (SWD) captures at the station and the average number of SWD captured in the northwest have been slowly increasing since this year’s initial detection of SWD at the end of June.

We caught a total of 30 SWD – 14 females and 16 males – in tart cherries at the station this week. Last week, SWD were detected on Old Mission, one in sweet cherries and one in grapes; Leelanau County, six in tart cherries, one in sweet cherries and one in raspberries; and Benzie County, six in tart cherries and three in grapes. SWD were not detected in Antrim County last week. We will continue to report weekly SWD captures on Fridays to FruitNet subscribers. We have received one report of SWD larvae in ripe fresh market sweet cherry fruit from an orchard in the southwest region.

Feeding damage such as stippling and bronzing on leaves from two-spotted spider mites and European red mites and webbing is noticeable in orchards and several growers are planning to make post-harvest miticide applications. Until today’s rain, Aug. 12, conditions had been very dry and the recent warm-hot temperatures have been favorable for rapid mite development. “Firing” is apparent in some orchards and may be a result of dry conditions and high mite populations.

Peachtree borer and American plum borer activity is ongoing at the station with an average of 25.5 greater peachtree borers, 18 lesser peachtree borers and 23 American plum borers per trap.

In apples, we caught an average of 185 second generation spotted tentiform leafminer moths at the station. A total of three codling moths and three obliquebanded leafrollers were caught at the station this week. Apple maggots were not detected this week and the first apple maggot fly captured at the station was on July 21. Some growers have sprayed for apple maggots and are hoping to have some activity against codling moths and obliquebanded leafrollers with this spray.

According to Michigan State University Extension, growers should not be concerned with SWD infesting apples. Since the arrival of SWD in Michigan, we have not observed SWD infesting healthy, undamaged apples.

Dr. Rothwell’s work is funded in part by MSU’s AgBioResearch

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