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Spotted Wing Drosophila (SWD) Update: August 7th. SWD Fruit Injury Increasing in Ulster and Dutchess County

Male SWD (Image. HVRL)

Male SWD (Image. HVRL)

Yesterday at the Hudson Valley Research Lab in Highland, NY we had the first capture of Spotted Wing Drosophila (SWD) in traps placed in peach as well as the invasive edge host plant, Tartarian Honeysuckle (Lonicera tartarica). No damage was observed to sound, undamaged peach, nor did we find infestations in honeysuckle fruit. Damage assessment have been relatively low to raspberry and blackberry in Ulster County compared to the past two years. In 20 fruit sample assessments for both eggs and larva in multiple Ulster sites we are showing a range of 4 to 15% fruit injury. That is a fraction of the injury we observed to these fruit at this time last season. Yet, it is on the rise and growers should begin management in brambles where the fly has been captured.

Tatarian Honeysuckle (Lonicera tatarica)

Tatarian Honeysuckle (Lonicera tatarica)

Of the small fruit grown and sampled in the Hudson Valley we have observed raspberry and blackberry to be a favored host of the SWD, relative to blueberry and strawberry. These commodities will require intensive management strategies. In raspberry or blackberry patches where SWD have been captured and or fruit injury has been observed, management should begin at the first available application window to reduce adult populations and egg laying. In these cultivars a tight management schedule of 3-4 days may be needed if populations continue to increase. Blueberry have been successfully managed with a 7-day program.

Rotating plots within a block may be needed to maintain daily harvesting while cleaning the brambles of all fruit to reset management and eliminate eggs and larva in fruit may be an important part of late season management. Removal and complete destruction of infested berries will also reduce newly developing populations to aid in management. Keeping fruit cold (34-38F) directly after harvest will arrest egg and larval development. Prolonged exposure to these low temperatures for 4d will dramatically reduce egg and larva survival.

Conventional and Organic Management Options for NYS grown small fruit:
Insecticides labeled in NYS to manage SWD

SWD Egg and respiratory horn on raspberry

SWD Egg and respiratory horn on raspberry

To date, SWD have been captured in the Hudson Valley counties of Westcester, Dutchess and Ulster in raspberry, blueberry and blackberry plantings. Given the increasing number of SWD finds we are seeing in the northeast, it would be wise to begin trapping efforts in brambles and blueberry fields as flies increase from localized to regional populations. Although very little damage has occurred in Hudson Valley fruit, It is likely that SWD damage to small fruit will begin over the upcoming week as adults establish and build in populations in berry patches.

Introduction: Spotted Wing Drosophila, Drosophila suzukii (SWD) is a vinegar fly native to East Asia. Established in the Eastern US since 2012, it has become an invasive insect pest of small fruit and to a lesser degree, cherry and grape. Information on insect biology is located here..

Monitoring: Traps we are presently using are made of red plastic 16 oz. solo cups and lids with a black band of electrical tape. Traps are baited with apple cider vinegar (ACV), as the attractant killing solution. Approximately 30, 1/8″ holes, are drilled around the top 3/4 of the cup, leaving a 3′ gap to pour out the ACV solution in a strip of 2″ x 2″ netting to access the number of captured flies. A yeast, flour & sugar bait mixed with water is added to a 5 oz. fixed position cup along the top edge.

SWD Egg on Raspberry.

SWD Egg on Raspberry.

SWD Red Solo Cup Trap. Image UNH

SWD Red Solo Cup Trap. Image UNH Cooperative Extension

The Cornell Spotted Wing Drosophila web site hosts a map of the counties in which SWD is being trapped. Updates on presence based on trap findings can be found here.

SWD Identification using key characteristics.

SWD Identification using key characteristics.