SWD Update 17 August 2011

Publication Date: 
SWD_08-17-11.pdf105.97 KB

Spotted Wing Drosophila Update for 8-17-11

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 fruit damage and economic losses to 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.

Management Material Update

• Imidan (Phosmet) now labeled for SWD management in blueberries in U.S.
o Click here for the new label.
o Preharvest interval (PHI) is 3 days. Re-entry interval (REI) is 24 hours.
o Efficacy data from Michigan State shows excellent results.
o Phosmet is an organophosphate.


• In southern growing areas caneberry and blueberry fields being monitored that haven’t received any insecticide applications are showing much greater larval infestation rates than those that have been on a regular treatment regime.
• Many caneberry fields are close to the end of or have finished harvest. In monitored southern region fields, high adult trap numbers and larval infestations are being found in left over fruit.
• In southern blueberries very low level sporadic fruit infestations have been detected even in some fields on a regular treatment regime.
• Many northern growing area fields are still reporting low trap catch numbers.
• As we get later in the year, geometric increases in SWD populations can be anticipated based on the last two seasons of experience.
• Given this increased pest pressure the interval between insecticide applications might need to be shortened to maintain an adequate level of control.
• There is some preliminary anecdotal evidence that Malathion will not give as long a residual control as was originally reported. In high pest pressure situations, growers are advised to take this under advisement.
• Growers should rely on past experience, fruit ripening stage and fruit sampling for larvae to make decisions on the timing of insecticide applications.
• The protocols for checking fruit for larvae are listed below. Many growers and processors have now implemented these to maintain fruit quality.
• The OSU-IPPC degree-day model currently predicts that 50% egg-laying of 2nd generation will occur close to August 28, 2011 in the mid-Willamette Valley.

SWD in the news

Strong safeguards are needed to protect native Michigan plants and crops—Editorial (8/14, Kalamazoo Gazette)
• (Michigan) Spotted wing Drosophila catches are picking up: Maintain monitoring if fields are still ripening (8/16, MSU Extension News)

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 cover fruit (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): 38 males/ 26 females. Raspberries (1): none. Blackberries (2): 5 males/4 females.
Linn County: Strawberries (8): 9 males/10 females. Cherries (2): 47 males/ 24 females. Raspberries (3): 19 males/8 females. Blackberries (6): 36 males/37 females. Blueberries (17): 13 males/14 females. Peaches/Nectarines (5):29 males/12 females. Plum (2): 17 males/9 females. Wild Habitat (20): 410 males/233 females. Caneberry (4): 20 males/ 26 females. Apple (2): 15 males/8 females.
Benton County: Cherries (2): no males/1 female. Raspberries (1): no males/1 female. Blueberries (2): 1 male/4 females. Peaches (3):5 males/no females. Wild Habitat (4): none.
Polk County: Blackberry (7): 2 males/1 female.
Marion County: Blackberries (3):4 males/3 females. Blueberries (2): 2 males/2 females. Peaches (6): 63 males/36 females.
Clackamas County: Strawberries (1): 3 males/3 females. Raspberries (2): 11 males/3 females. Blackberries (2): no males/4 females. Blueberries (7): 5 males/3 females. Tayberries (1): 8 male/4 females. Honeysuckle (1): no males/4 females.
Yamhill County: Cherries (1): 7 males/8 females. Blueberries (1): none.
Washington: Cherries: none. Blackberries (5): 1 male/4 females. Blueberries (4): none. Peaches (1): none. Plums (1): none.
Multnomah County: Cherries (1): 8 males/13 females. Raspberries (3): no males/3 females. Blackberries (4): 1 male/5 females. Blueberries (2): 4 males/no females. Peaches (4): no males/1 female. Boysenberries (1): none.

Southwest Washington Public Scouting Program
Clark/Cowlitz/Lewis Counties: Cherries (2): 4 males/5 females. Raspberries (28): 30 males/45 females. Blackberries (6): 3 males/17 females. Blueberries (25): 2 males/ 2 females. Peaches (2): 5 males/3 females. Plums (1): no males/ 1 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.

Southwestern British Columbia
Click here for the 8/15/11 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)