SWD Update 9 August 2011

Publication Date: 
SWD 08-09-11ajd.pdf105.04 KB

Spotted Wing Drosophila Update for 8-9-11

This Update is a collective effort. It is composed by Peerbolt Crop Management with contributions from OSU, USDA-ARS, WSU, B.C. Ministry of Agriculture and various northwest berry industry people.
SWD Information Websites

Peerbolt Crop Management
Oregon State Univ.
B.C. Ministry of Ag.
WSU Westside
WSU Eastside


The risk of economic losses from this pest is now high for any vulnerable ripening/harvesting fruit. SWD populations will continue to increase at an accelerating rate until the end of the season.


• Be prepared. Be conservative & pro-active. If you or your neighbors had SWD pressure last year, take all reasonable precautions to minimize the risk this insect poses to your crop.
• Many caneberry fields are close to the end of harvest and fruit quality is declining. As there is less economic incentive to maintain an insecticide program for SWD management in these fields, growers are tending to let up.
• In blueberries last year, and this year, serious SWD pressure has held off until just about the end of Duke season and other late harvested blueberry varieties. There are now more reports of higher trap counts and isolated, sporadic fruit infestation in blues. Numbers of flies caught in vinegar traps averaged 19 flies per trap per week in the mid-Willamette Valley based on approx. 70 traps, compared to last week’s count of 8 per trap. The number of SWD locations and trap catch totals found in Hood River/Dalles roughly doubled compared to last week; numbers tripled in Douglas county area.
• Reports of infested fruits (cherry, raspberry, blueberry) from no-spray backyards greatly increased. Growers should rely on past experience, fruit ripening stage and fruit sampling for larvae for making decisions on the timing of insecticide applications.
• Increases in adult trap counts, incidences of larval infestations, and the levels of those infestations are all anticipated from now through the end on the season.
• It is strongly recommended that growers with fruit coloring and/or harvesting have a SWD management program in place that includes both fruit sampling for larvae and regular control applications.
• The salt solution sampling method is a valuable additional tool for growers and processors. Allowing them to determine infestation levels well before the fruit enters the processing plant.

SWD in the news

Dreaded pest a virtual no-show (8/4/2011, Capital Press, Wenatchee WA).


Guidelines for checking the fruit for SWD larvae in the field

These suggestions are based on techniques that various public researchers and industry personnel have been developing over the past year and a half. If any of you have ideas for improvements to these protocols, please pass them along. We’re all in this together.
• Depending on size of fruit (strawberries take longer than caneberries or blueberries), the larvae will emerge from the fruit into the salt solution in a short period of time.
• The smaller the larvae and the lighter the infestation, the more difficult it is to see the larvae.
• Excellent lighting when looking for the larvae is critical to being able to see the smaller ones.

Present suggested methods:
For scouts/field checking (We have created a video of this larvae-checking method.):
1. Collect a sample of fruit to be tested (Strawberries: 25-30 per sample, Caneberries/blueberries: 75 per sample)
2. Put fruit in a gallon size sealable plastic bag.
3. Pour in enough of the salt water solution to allow the fruit to float (solution is: 1 cup of salt per gallon of water).
4. Mark bag with field code/date.
5. For a quick check in the field after a designated period of time (at least 15 minutes) holding the baggie up to light. This helps to see the larvae in the solution
6. For a more thorough examination, after a designated period of time (at least 15 minutes), pour the fruit and salt solution out into a shallow tray and use a piece of wire mesh screen to hold the fruit down making it easier to separate the larvae from the fruit.

For processors or fruit handling stations:
1. Collect a two pound sample of fruit to be tested.
2. Put the sample into a shallow tray and cover with the salt water solution (1 cup of salt per gallon of water).
3. After a designated period of time (at least 15 minutes) use a piece of wire mesh screen to hold the fruit down to make it easier to separate the larvae from the fruit.

Regional Monitoring (South to North)

Oregon Public Scouting Program (Number of traps checked this week in the crop in parentheses). This scouting program & reporting system are being funded by a USDA SCRI grant, A Northwest Center for Small Fruit Research grant; the Washington Red Raspberry Commission & the Washington Blueberry Commission.
Lane County: Strawberries (1): no males/1 female. Cherries (2): 5 males/ 8 females. Raspberries (1): no males/ 1 female. Blackberries (2): 1 males/9 females.
Linn County: Strawberries (10): 13 males/8 females. Cherries (2): 75 males/ 28 females. Raspberries (2): 3 males/3 females. Blackberries (7): 10 males/13 females. Blueberries (8): 1 male/2 females. Peaches/Nectarines (3):7 males/17 females. Honeysuckle (1): no males/3 females. Wild Habitat (19): 137 males/109 females. Apple (2): 5 males/4 females.
Benton County: Cherries (2): 3 males/1 females. Raspberries (1): 1 male/no females. Blueberries (2): none. Peaches (3): 2 males/1 female. Wild Habitat (4): 1 male/4 females.
Marion County: Strawberries (1): 2 males/1 female. Blackberries (3):16 males/13 females. Blueberries (4): none.
Clackamas County: Strawberries (1): 1 male/2 females. Raspberries (2): 2 males/1 female. Blackberries (2): 6 males/8 females. Blueberries (6): 5 males/2 females. Tayberries (1): 9 male/no females. Honeysuckle (1): 1 male/no females.
Yamhill County: Cherries (4): 5 males/6 females. Blackberries (5): 2 males/1 female. Blueberries (1): none.
Washington: Blueberries (4): none. Peaches (1): none.
Multnomah County: Cherries (1): 7 males/9 females. Raspberries (3): 1 male/1 female. Blackberries (3): 4 males/3 females. Blueberries (2): 2 males/5 females. Peaches (3): none. Boysenberries (1): 4 males/1 female.

Southwest Washington Public Scouting Program
Clark/Cowlitz/Lewis Counties: Cherries (2): 4 males/6 females. Raspberries (27): 30 males/32 females. Blackberries (6): 2 males/4 females. Blueberries (22): 1 male/ no females. Peaches (1): 5 males/1 female.

Eastern Washington--WSU Reporting Site
Click here for the WSU Eastern Washington SWD reporting site.
Most recent posts on the WSU site:
• Friday, 5 August: “First fly has been found in the Wenatchee area. This makes 8 regions with positive traps.”
• Thursday, 4 August: “6 males in 4 traps found yesterday, in Orondo, Rock Island, and Mattawa districts; the latter two are first catches for these districts. To date, 7 regions have positive catches.”

Western Washington--WSU Public Scouting Program
This scouting program & reporting system are being coordinated by Whatcom County Extension & funded by the Washington Red Raspberry Commission, the Washington Blueberry Commission & the Washington State Commission for Pesticide Registrations.
Click here for the Home site with links to all the counties and site use information.
Click here for the demonstration video on how to use this resource.
• Here are individual county links (south to north): Clark County, Cowlitz County, Lewis County, Pierce County, King County, Snohomish County, Skagit County, Whatcom County.

Southwestern British Columbia
Click here for the 8/8/11 SWD Monitoring Report for Southwestern BC from the BC Ministry of Ag.  Information from this recent report:
• “Trap catches of SWD flies continue to increase. Fruit is susceptible to damage from SWD when it ripens (colours). Expect numbers to increase from now on. Treatment is critical now.
Raspberries: Consider a post-harvest full-canopy spray to decrease the potential of SWD moving into neighbouring blueberry fields.
Blueberries: Incorporate SWD sprays into your harvesting schedule at ten-day intervals.”

Management Material Resources

Oregon & Washington
• Blueberries: SWD pesticide options & information
• Raspberries & blackberries: SWD pesticide options & information
• Strawberries: SWD pesticide options & information
British Columbia (6/28/11): SWD Management in BC Berry Crops (with insecticide options listed)