Monday, July 18, 2011

Spotted Wing Drosophila Alert July 17

On June 29 I posted on the threat of a new pest, the spotted wing drosophila (SWD). This post is on the latest development of SWD in NC from Dr. Hannah Burrack.

Spotted Wing Drosophila Alert
For commercial fruit growers

spotted wing drosophila (SWD, Drosophila suzkii) larvae have been found in North Carolina grown caneberries. Growers in areas with a known history of SWD should undertake an aggressive management program for this potentially devastating pest. Growers in areas without a history of SWD should determine the status of SWD on their farm by sampling fruit and trapping adult flies.

SWD in North Carolina

SWD has been detected in the following 23 North Carolina counties:
Anson, Ashe, Burke, Bladen, Craven, Davidson, Edgecombe, Greene, Henderson, Johnston, Lee, Lenoir, Lincoln, Montgomery, New Hanover, Onslow, Pender, Person, Randolph, Rowan, Sampson, Wake and Wayne.

SWD larvae have been found in fruit in the counties indicated in bold. In all of the listed counteis, adult SWD have been captured in traps.

SWD can feed on blueberries, blackberries, raspberries, strawberries, grapes figs, peaches, cherries, and many other soft skinned fruits, both cultivated and wild.

Growers of these crops in and around the 22 counties where SWD has been detected should consider themselves to be in areas witha history of SWD and manage accordingly.

SWD Management

Because SWD is new to North Carolina, our current management strategy relies on insecticides. You can find lists of registered insecticides and their probable efficacy against SWD at

Select insecticides that will be effective against SWD (those expected to provide "excellent" control), and apply insecticides at the high end of the labeled rate range. Apply insecticides every 7 days, ideally rotating between at least two insecticides with different modes of actions (MOAs).

Always observe proper preharvest intervals and be aware that many insecticides have maximum residue levels (MRLs) for the United States and other countries. These residue levels may potentially occur before the maximum number of allowable insectice applications per season is reached. USDA maintains a database of MRLs (

Check with your marketer or wholesaler before using a new insecticide on your crop to ensure that it is acceptable in all locations where your fruit may be sold.

SWD larvae take 7-10 days to mature, so larvae found in fruit now are the result of egg laying activity over 1 week prior. Larvae inside fruit cannot be controlled; only adult SWD can be killed with insecticides.

Sanitation is crucial for SWD management. All ripe fruit (marketable or not) must be removed from the field and disposed of. Culls should not be left on the ground or plant. Freezing or "baking" in clear plastic bags placed in the sun will kill larvae, Burying or composting may not.

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