SWD Update 13 September 2011

Publication Date: 
SWD 09-13-11.pdf88.96 KB

Spotted Wing Drosophila Update for 9-13-11

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

SWD Research

The efficacy of Sake as a trap attractant for SWD (8/31, Mark Bolda, UC Extension)


SWD in the news

Ontario spotted wing drosophila update (9/6, Fruit and Vegetable Magazine)
• (Michigan) SWD catches increase (9/2, MSU Extension News)
• (North Carolina) Vinegar fly poses danger to fruit crops (9/9, ENC News)


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
Blueberries: (Friday, September 12) (From Mark Sweeney, BC Ministry of Ag Berry Specialist) SWD numbers are heating up like the weather. I just had a report from a grower seeing some minor larval infestation where no flies have been caught in apple cider vinegar traps – I agree with the comment regarding the need for a better bait.

Northern Washington, Whatcom County
Blueberries: (Friday, Sept. 9) My apple cider vinegar traps worked better for me than they did last year. Placement is critical and may have been better this year. However, I only caught about 6 males all season. Also saw shorter residual as the season went on with Mustang Max and Malathion. Maybe we need a decreasing spray interval, like 10/9/8/7 days as we go through harvest.

Northern Washington, Skagit County
Blueberries: (Saturday, Sept. 10) SWD pressure seems to be down quite a bit from last season; both trap counts and what we can find in the field are negligible. Mustang Max has been the spray of choice on conventional and I have been pleased with rotation of Spinosad (Entrust) and Oxidate on the organics. Few males in the traps this year.

Willamette Valley, Oregon and SW Washington
Blueberries/blackberries/strawberries: (Friday, Sept 9) Late season blacks are being ‘hounded’ by SWD. If they aren’t sprayed every 5-7 days, there’s a big chance of infestation. Blues and day neutral strawberries are also seeing pressure with some larval infestations being found. Malathion is not holding up for seven days. Only Mustang Max is giving us any real residual activity under this type of pressure. Earlier in the year is a different story. Maybe the Malathion knocks them out enough that, with a lot fewer adults around, it takes that much longer to build back up to a noticeable level. That might be something that still applies further north. The other SWD issue is that there seems a growing consensus that the apple cider vinegar bait isn’t cutting it. We need a stronger attractant.


Regional Monitoring (South to North)

Oregon Public Scouting Program
This scouting program & reporting system is 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.
• Use the above link and go to Northwest quadrant of Linn County chart for the highest numbers recorded this past week. (Examples: 4 Wild habitat traps had 2,204 total, 2 blackberry traps had 638 total flies, 2 plum traps had 154 total flies)

Western Washington--WSU Public Scouting Program
This scouting program & reporting system is 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 9/12/11 SWD Monitoring Report for Southwestern BC from the BC Ministry of Ag. From this report:“Fly numbers have increased exponentially. All regions being monitored have flies. Fruit is susceptible to damage from SWD when it ripens. Larval infestation has been reported. Control of SWD flies is critical if ripening commercial fruit is present.”
Click here for the B.C. Blueberry IPM Report of 9/11/11 with trap counts reported. From this report: “SWD have increased significantly over the past week. Late season blueberry varieties are highly susceptible to damage. Low levels of fruit infestation have been reported. All blueberry growers with ripe or ripening fruit should continue to apply insecticides for SWD at 10 day intervals to protect 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. Lightly crush berries in bag.
3. Pour in enough of the salt water solution to allow the fruit to float (solution is: 1 cup salt per gallon 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 white tray. Optional: 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)