SWD Update 3 July 2012

Publication Date: 
SWD 07-3-12.pdf29.12 KB

Spotted Wing Drosophila Update for 7-3-12

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

Oregon and SW Washington SWD

Processed Strawberries

• June bearing strawberries are finished in SW Washington and Oregon.
• Most of our SWD monitoring traps have been removed from strawberries and moved to caneberry and blueberry fields where ripening crops are more at risk.
• A post harvest insecticide application is advised if the field is adjacent to other berry or stone fruit crops to prevent the strawberry field from being a breeding site for SWD.


Raspberries & Blackberries

• Unlike the previous two seasons when SWD larvae were not found in raspberries until late season, there’s very strong evidence that even early picks this year could see SWD larval contaminants.
• Harvest is ongoing in raspberries and just beginning in blackberries in SW Washington and Oregon. There’s a lot of ripe and/or ripening fruit in all fields.
• Almost all commercial plantings have received a pre-harvest broad spectrum insecticide application within the last 10 days that has suppressed SWD populations.
• In higher risk fields an insecticide application 10-14 days after the first spray is recommended.
• We are only seeing major problems with high trap numbers and a few larvae in some of the fruit samples from sites that are small field size within multiple berry and stone fruit plantings. This type of setting could require more insecticide applications and shorter interval between applications
• In caneberries with any SWD larvae in them, the fruit softens & falls apart much more visibly than in strawberries. Pay particular attention to berries that look like they’re prematurely soft/over ripe.
• It is advised to monitor fruit quality closely and take appropriate actions to prevent crop losses.



• Duke harvest has started. We’ve now got many more monitoring traps in blueberries.
• While these traps give us some data on SWD populations it’s strongly advised to not make management decisions on trap numbers. This monitoring system is not reliable enough to be able to do that.
• Unlike the previous two seasons when SWD larvae were not found in blueberries until after the Duke harvest, there’s a higher risk this year that the early ripening cultivars (like Duke) could see SWD larval contaminants issues.
• When they begin to ripen, late ripening cultivars (like Liberty, Aurora and Elliott) can expect to see even higher pressure from SWD than the last two years due to higher population levels.
• Almost all commercial plantings have received at least one broad spectrum insecticide application within the last 10 days that has suppressed SWD populations.
• While some fields show increasing catches of SWD adults, no larval contamination has been picked up in the salt tests we’ve been doing.
• It is advised to monitor fruit quality closely and maintain a preventative schedule of insecticide applications to mitigate the risk of potential crop losses due to SWD larval contamination.


SWD Risk Factors

It’s becoming clearer which field characteristics increase the chances of having SWD infestations. This is still a work in progress but observations over the last three seasons indicate the following:
Increased Risk:
• Borders of field have wild blackberries, wild cherries or other favored overwintering habitat.
• Field is relatively small in size and is part of a mixed crop farm with other susceptible crops adjacent (Example: 1-3 acre plantings of strawberries, raspberries, blueberries with 5 acre cherry and peach orchards).
• Caneberries appear to be preferred over blueberries and strawberries.
• The later the harvest season the more the risk with late season caneberries the most susceptible.
• U Pick/ Fresh market fields that are difficult to treat with insecticides on a regular schedule.

Decreased Risk:
• Field is bordered by grass seed fields or other non host plantings.
• Field is relatively large and doesn’t border other fields of SWD susceptible crops.
• Harvest season is earlier (Example: Duke is lower risk than Liberty in blueberries).
• In general, caneberries are higher risk than blueberries. But the late season blueberries are under a very high risk due to the higher insect populations.


SWD in the news

On the front lines of an invasion (6/27, NC State Bulletin)
SWD numbers building rapidly in southwest Michigan (7/1, Michigan State Extension)
SWD rebounding in the Pacific Northwest (6/26, Growing Produce)


Updated SWD Resources

Managing spotted wing drosophila update (7/2, Michigan State Extension)
Update on SWD management in Oregon Sweet Cherries  (Dr. Peter Shearer, OSU, Hood River Station)
The latest APHIS Map of where SWD is in the United States.
• Joe DeFrancesco, OSU pesticide specialist, has updated the lists of SWD pesticide options for Oregon and Washington berry crops originally done in April of 2011.
o For the updated blueberry list click here.
o For the strawberry list click here.
o For the caneberry list click here.


Regional Monitoring (South to North)

Oregon Public Scouting Program count for the week ending on 6/29
(Number of traps checked this period in the crop in parentheses).

This scouting program and reporting system are being funded by a USDA SCRI grant, and a Northwest Center for Small Fruits Research grant
Linn County: Apples(1): none. Blackberries (7): no males/ 1 female. Black Raspberries (2): none. Blueberries (20): 4 males/6 females. Other caneberries (4): no males/ 1 female. Cherries (2): 9 males/6 females. Grapes (2): none. Honeysuckle (1): none. Peaches (2): none. Pear (1): none. Plums (2): none. Raspberries (3): 1 males/ no females. Strawberries (12): 1 male/2 females. Tayberries (1): none. Wild Habitat (19) 17 males/45 females.
Benton County: Cherries (2): no males/1 female. Nectarines (1): 3 males/1 female. Peaches (2): 3 males/no females. Raspberries (1): none. Strawberries (1): no males/ 1 female. Wild Habitat (4) none.
Marion County: Blackberries (3):1 male/9 females. Blueberries (9): none. Strawberries (22): none. Raspberries (2): none. Cherries (4): 30 males/27 females.
Lane: Blackberries (1):none. Cherries (2): none. Raspberries (2): none. Strawberries (1): none.
Polk: Blackberries (3):none. Cherries (2): 2 males/no females.
Clackamas County: Blackberries (1):3 males/no females. Blueberries (7):1 male/no females. Honeysuckle (2): none. Strawberries (4): 3 males/ no females. Raspberries (10): 3 males/1 female. Tayberries (1): no males/1 female.
Yamhill County: Blackberries (4):none. Blueberries (2):none. Cherries (6): 1 males/ 1 female. Strawberries (9): none.
Multnomah County: Blackberries (4): 4 males/9 females. Raspberries (2): no males/ 3 females. Strawberries (7): 7 males/ 40 females. Cherries (1): 5 males/8 females. Salmonberry (3): none.


Southwest Washington Public Scouting Program for the week ending on 6/29

Clark/Cowlitz/Lewis Counties: Blackberries (3):1 males/6 females.  Raspberries (1): 6 males/11 females. Strawberries (14): 48 males/62 females. Cherries (4): 37 males/16 females.


Eastern Washington

Click here for the WSU Eastern Washington SWD reporting site.
Latest report from the site--Monday, July 2: “We currently have 12 of 17 regions positive for SWD at this point. Trap catches remain low, but are not a good indicator of risk. Be aware that lack of trap catch in some regions may reflect low trap density rather than low fly density. Also note that 6 drosophila larvae have been found in porch samples at packinghouses, and so far, 5 have been confirmed SWD. This number of finds before July is in contrast to a single find in late August of 2011. Wisdom dictates that cherries at a susceptible stage should be protected from this pest.”


Western Washington--WSU Extension Scouting Program

This scouting program and reporting system are being coordinated by Whatcom County Extension and funded in part by the Washington Red Raspberry Commission.
Click here for the program’s website. “A limited number of raspberry fields are now being scouted covering a diverse range of area in Whatcom, Skagit, and Pierce counties.” For more information contact Colleen Burrows at 360-676-6736 x 22 or cburrows@wsu.edu. No recent reports have been posted.


Columbia Gorge

Report from Steve Castagnoli, OSU Hood River Extension
• “Overall SWD trap catch this week was down from the previous week with 8 males and 30 females versus 38 and 45, respectively, the week before. And although trap catch was still widely distributed in the area, no SWD were caught in commercial orchards this past week. Cherries in much of the Hood River Valley are now in the stage of development when they are at high risk of damage from SWD.”


British Columbia

SWD Management in BC Berry Crops (with insecticide options listed)
Click here for the SWD Ministry of Agriculture site.
o Click here for the June 22nd report for coastal B.C. From that report: “Only 2 SWD flies caught in traps in blueberry fields, and none in the raspberry fields in this project, however: 21 SWD flies caught in a separate project, including hedgerow and field edge traps (108 traps in total), and SWD flies are emerging from wild salmonberry collected June 6-8. “
Click here for the B.C. Southern Interior Valleys report for the week of June 15-21.


Guidelines for checking the fruit for SWD larvae

These suggestions are based on techniques that various public researchers and industry personnel have been developing over the past couple of years. If any of you have ideas for improvements to these protocols, please pass them along. We’re all in this together.

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.