Grand Rapids, Michigan, small fruit regional report – September 4, 2012

Harvest of small fruit crops continues with minimal problems, however, spotted wing Drosophila is advancing in some fields.

The harvest of small fruit crops continues without many problems due in part to the good weather conditions that have prevailed during the past few days. Much of the blueberry crop has been harvested with only few fields in Ottawa, Muskegon, Oceana and other counties north of Ottawa still harvesting late season varieties like Elliott.

In general, yields have been lower than expected due to spring frosts and summer drought that affected the region during the 2012 crop season. These climatic conditions affected substantially the size of the berries and the volume harvested. In addition, growers harvesting late season varieties or harvesting the remnants of the crop are facing a serious problem associated with the presence of spotted wing Drosophila (SWD) larvae in harvested fruit. In most cases, SWD contaminated fruit has been diverted for juice, which results in important economical loses for those growers affected by this situation.

Similar problem are facing small fruit producers whose major crops are raspberries, blackberries and strawberries. SWD is advancing, unstoppable in fields where growers are using organic compounds or are not spraying conventional insecticides. At this moment, raspberry growers in Ottawa, Kent, Montcalm and Mecosta counties are battling the presence of SWD in their crops. One major problem to succeed in controlling this insect is that growers are unaware of its presence and by the time they realize they have a problem, the pest is already established in their fields.

To make matters worse, insecticide treatment applied in fields with heavy presence of SWD are not producing the expected results. Fruit sampled for SWD larvae after the pesticide applications still is showing some level of SWD infestation. Currently, pyrethroid or Malathion applications seem to be ineffective to control the presence of SWD.

So far, the presence of the SWD in most berry crops of Michigan has disrupted already established integrated pest management (IPM) programs. It may require a renewed effort on the part of growers and MSU Extension to rethink the way forward in dealing with the SWD menace. The MSU small fruit team has updated the guidelines for management of SWD for blackberries and raspberries and is available online at the MSU IPM Control Recommendations for Spotted Wing Drosophila website.

Among all the bad news, there is a good news for blueberry growers that are battling the SWD. EPA has allowed the use of Guthion for another year. Growers will be able to purchase Guthion until the end of September 2012 and use it for the 2013 blueberry season. The extension provided by the EPA will allow us more time to develop a strategy for the control and management of the SWD. (For more information, read Azinphos-methyl phase-out update.)

However, EPA has decided to maintain the September 30, 2012, effective date for cancellation of the uses of Guthion on blueberries. Distribution or sale of AZM after September 30, 2012, remains prohibited. Read the complete EPA decision.

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