SWD Update 23 August 2011

Publication Date: 
SWD 08-23-11ajd.pdf189.71 KB

Spotted Wing Drosophila Update for 8-23-11

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


Spotted Wing Drosophila, all berries. The risk of fruit damage and economic losses by this new fruit pest continue to increase for any berry crop still harvesting in the Northwest. It is highly recommended to take all appropriate measures to mitigate this risk. Fly numbers are expected to climb exponentially over the next two weeks according to the degree-day model.

Distribution of Spotted Wing Drosophila in the US 2011

Presently, 15 mainland states have reported the presence of SWD including California, Oregon, Washington, Florida, Utah, Louisiana, Michigan, New Jersey, North Carolina, Virginia, Pennsylvania, South Carolina, Wisconsin, Virginia, and Connecticut.

Regional Comments

These comments are from individuals within the region and are their particular observations. They are included to give an impression of the present 'state of the industry' and regional activities in regard to SWD.

British Columbia, Fraser Valley (Monday, August 22) From Mark Sweeney, BC Ministry of Ag Berry Specialist:“Given the late, weird season and the much lower than expected SWD trap counts, I’m worried that some blueberry growers may be getting complacent and letting down their guard just when numbers start to ramp up. We have seen another increase this week and, with Himalayan blackberries fruiting everywhere, can expect an increase in pressure as we get into the second pick Bluecrop and as Elliott ripens.
I’ve spoken with some growers who look at the weekly trap counts and if they see zeros in a particular region think they are OK, not realizing that the counts are from a couple of sample of fields which may not be indicative of theirs.
Tracy Hueppelsheuser’s (BC Ministry of Ag Entomologist) work continues to shows much higher trap counts in wild borders adjacent to fields compared to within fields.
Light fruit infestations are being detected in unsprayed fields, but nothing like last year.”

Northern Washington, Whatcom County
Blueberries: (Monday, 8/22) Very few SWD in the traps, however we are keeping on a 10-12 day spray schedule.
Raspberries: (Monday, 8/22) The 7-10 day spray intervals on the SWD insecticides seemed to do the job. I wonder (out loud) if we need to spray the whole bush, or just the bottom 2 feet? They seem to gather right close to the ground in the heaviest, coolest part of the canopy

Northern Washington, Skagit County
• (Tuesday, 8/23) SWD trap counts lower than last season so far with the largest numbers along field edges bordering wooded areas and brush lines. Mustang and Entrust are providing good control based on trap numbers and processing sampling. We were unable to get helicopters in for applying applications this year. They were too busy in Oregon with timber we’re told.

Eastern Washington
Blueberries: (Monday, 8/22) No SWD to speak of.

Western Oregon, Willamette Valley
Blueberries: (Tuesday, August 23) (Organic production) Not much in the traps for SWD but I think now is the time for it to sneak up on us. However, this is a case by case situation. A u-pick blueberry farm has high numbers of flies (as high as ~100/trap/week).The three day pre harvest interval wait with Entrust before you can pick is challenging to match with harvest needs.
(Tuesday, August 23) From Tom Peerbolt, Senior Consultant, Peerbolt Crop Management: The SWD situation is certainly getting ‘interesting’ in the Willamette Valley and SW Washington. There’s been a big increase in trap counts and overall pressure. I know from our infield sampling that there are detectible levels in some fields, especially in post-harvest caneberries after treatment regimes have been suspended. From our checks, post-harvest raspberries are often heavily infested and post-harvest blackberries are also often infested.
• In blueberries we are picking up occasional, sporadic low levels of infestation even in some fields that have been on a strict application regime. Some of the factors that are standing out: 1) Some chronic infestations seem associated with border wild cherries that are very infested; 2) Some specific valley regions have much more pressure than others; 3) (Caution: The following is anecdotal information only!) Malathion, and probably the Spinosads, under high pest pressure, don‟t seem to give as long a residual as has been listed. Mustang Max is becoming even more the standard than it was.
From Amy Dreves, Oregon State University Entomologist: Fly numbers in traps placed at no-spray blueberries in the mid-Willamette Valley continue to catch a significant number of flies. A percentage of infested fruit (~25% loss) is being found at organic, no-spray, and u-pick operations compared to the conventional spray operations. In mid-Willamette Valley, 29 flies/trap/week were found across all traps placed (very similar to last year’s record), and as high as 55 flies/trap/week on organic farms across all fruit types. However, highest trap counts are still being found on wildland borders (Himalayan blackberries and up in trees) adjacent to fields compared to within fields. Increased damage is found in the shaded areas of blueberry plants.

SWD in the news

UK fruit under threat from a new type of fly (8/19, The Grocer)
Spotted Wing Drosophila in the Northeast (U.S.) Northeastern IPM Center
New Jersey’s fruit industry faces threat from new pest (8/23, PerishableNews.com)
USDA confirms fruit pest in New Jersey (8/23, The Packer)

Regional Monitoring (South to North)

Oregon Public Scouting Program for the week ending on 8/19 (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.
Linn County: Strawberries (6): 18 males/11 females. Cherries (2): 110 males/ 47 females. Raspberries (3): 17 males/22 females. Blackberries (7): 103 males/57 females. Blueberries (31): 29 males/9 females. Peaches/Nectarines (5):22 males/37 females. Plum (2): 31 males/20 females. Wild Habitat (23): 488 males/299 females. Apple (2): 7 males/15 females.
Benton County: Cherries (2): 7 males/1 female. Raspberries (1): 3 males/3 females. Blueberries (2): 4 males/2 females. Peaches (3):8 males/7 females. Wild Habitat (4): 6 males/10 females. Caneberry (5): 24 males/ 44 females.
Marion County: Strawberries (2):6 males/6 females.
Clackamas County: Strawberries (1): 4 males/2 females. Raspberries (2): 2 males/5 females. Blackberries (4): 11 males/3 females. Blueberries (6): 2 males/2 females.
Washington: Blueberries (1): none. Peaches (1): none. Plums (1): none.
Multnomah County: Cherries (1): 4 males/19 females. Raspberries (4): no males/2 females. Blackberries (3): no males/12 females. Blueberries (2): 3 males/4 females. Peaches (4): 3 males/9 females. Boysenberries (1): no males/2 females.

Southwest Washington Public Scouting Program for the week ending on 8/19
Clark/Cowlitz/Lewis Counties: Cherries (2): 22 males/24 females. Raspberries (23): 84 males/110 females. Blackberries (6): 8 males/5 females. Blueberries (29): 13 males/ 12 females. Peaches (2): 2 males/3 females. Plums (1): 7 males/ 6 female.

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.

Eastern Washington--WSU Reporting Site
Click here for the WSU Eastern Washington SWD reporting site.
Most recent post on the WSU site: 19 August 2011: “First trap catch in the Othello area. The following is a summary for the Beers program traps: Trap catches remained elevated this week, with two-thirds of the catches in the south (Mattawa and Tri-Cities).
• 5,231 samples processed to date.
• 126 SWD caught to date; 43 the week of Aug 14-19.
• 123 in cherries, rest in stone fruits and blueberries.
• 34% of total caught the past week, 8.9% of the samples positive.”

Southwestern British Columbia
Click here for the 8/22/11 SWD Monitoring Report for Southwestern BC from the BC Ministry of Ag.
Click here for the B.C. Blueberry IPM Report of 8/20 with trap counts reported.
• From this report: “SWD flies continue to be caught in blueberry fields throughout the Fraser Valley. Low levels of fruit infestation have been reported. SWD is a serious harvest contaminant. All Blueberry Growers with ripe or ripening fruit should apply insecticides for SWD at 10 day intervals to protect the fruit from infestation.”

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). The longer the fruit remains in the tray or in a clear baggie, more larvae will exit fruit, if present.
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.

SWD 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)