SWD Update 31 August 2011

Publication Date: 

Spotted Wing Drosophila Update for 8-31-11

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.

SWD Management Materials Update

Suspected tolerance to Pyganic (pyrethrin) found in spotted wing Drosophila (8/23, UC strawberries and caneberries blog)

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 From Mark Sweeney, BC Ministry of Ag Berry Specialist: (Monday, August 22) “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. They do not realize that the counts are from a couple of samples 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.”

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

Willamette Valley, Oregon and SW Washington
Blueberries: (Monday, August 29) Light SWD infestation (larvae in the berries) showed up in blocks of Bluecrop, Rubel, and Bluejay, and the timing between our insecticide applications was shortened. SWD traps with multiple baits were not effective at predicting SWD infestation; we caught our first flies on the same week that larvae were discovered. Our larvae infestation was too light to be detected in the salt dunk flotation at the dock. The problem was discovered by hyper diligent employees on the sorting belt. It appears that SWD is getting started in overhead irrigated blocks protected by helicopter insecticide applications. Is the helicopter coverage thorough enough and/or are we washing off too much of our residual control with the overhead irrigation? Moderate to heavy SWD larval infested fruit from outside growers has been caught with the salt dunk flotation method at the dock.

From Tom Peerbolt, Senior Consultant, Peerbolt Crop Management & Coordinator of the public scouting program (Wednesday, 8/31)

  • The past week saw another increase in SWD trap counts in the region as well as more incidences of larval infestations on berry and stone fruit crops.
  • There is an increasing divergence in trap counts between fields still being treated with regular insecticides and those that have suspended insecticide applications and/or have not received any. Untreated areas are rising to much higher levels.
  • Late season blackberries, late season blueberries, and primocane raspberries are all seeing very significant pest pressure.
  • As the season develops, it’s seems more evident that we need a better attractant material than the apple cider vinegar we’re now using.

From Amy J. Dreves, Research and Extension Entomologist, Oregon State University

  • Larval infestations increase on wild Himalayan blackberries on borders of commercial fruit crops (up to 100% infested). Fly counts higher at elevations greater than 12 feet in trees bordering fruit crops.
  • SWD flies visible and active in shady areas of fruit crops.
  • SWD incidence of larval infestation showing up in fall-bearing strawberries, blackberries and raspberries once fruit is ripe.
  • Female trap counts increasing.

SWD in the news

New fruit pest has growers and exporters on edge (8/25, Yakima Herald)
It’s the season of annoying little flies (8/24, Chinook Observer)

Regional Monitoring (South to North)

Oregon Public Scouting Program 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.
Click here to access SWD trap counts by county quadrant and specific crop for Western Oregon and Southwest Washington sites being covered by this public scouting program.

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.

Southwestern British Columbia
Click here for the 8/29/11 SWD Monitoring Report for Southwestern BC from the BC Ministry of Ag.
Click here for the B.C. Blueberry IPM Report of 8/27 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. Mid and late season blueberry varieties remain susceptible to damage. 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).
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)