SWD Update 5 July 2011

Publication Date: 
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Spotted Wing Drosophila Update for 7-5-11

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

New developments this week

SW Washington/Willamette Valley: This last Thursday (6/30), using the salt solution protocols listed below, we recovered three Drosophila species larvae from a strawberry field in SW Washington.

• In consulting with our regional public & private entomologists and Extension agents, we found there are other species of Drosophila that can be found infesting strawberries in the field as they get over-ripe.

• There’s no way at this point to identify Drosophila species from larvae. Larvae would need to be recovered alive and reared out to identify to species.

• As it was before we had SWD in the area, it is possible that over-ripe strawberries could have varying levels of drosophila infestation, emphasizing the importance of harvesting all fruit in a timely manner.

Willamette Valley: A cherry orchard that has not received any insecticide applications this spring was found to have a significant infestation of SWD larvae.

Willamette Valley: An early ripening fresh market caneberry variety that has ripening berries and has not received any insecticide applications has also been reported to have a low infestation of SWD larvae.


• Trap counts continue to rise at a relatively slow rate over the previous week but are anticipated to rise more quickly over the next few weeks.
• Please take a very conservative approach to SWD management decisions. Our ability to accurately assess the risk posed by this insect on an individual field basis is still very much a work in progress.
• Once ripe fruit is present in the field the traps’ ability to attract adult flies is much diminished.
• In view of this, growers & fieldmen are advised to rely more on regular sampling of the fruit using the salt solution method to monitor SWD once there is ripe fruit.
• The salt solution sampling method is a valuable additional tool for growers and processors. Allowing them to determine infestation levels well before the fruit enters the processing plant.

Draft 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.

Present PCM Method:

• Collect a sample of fruit to be tested (Strawberries: 25-30 per sample, Caneberries/blueberries: 75 per sample).
• Put fruit in a gallon size sealable plastic bag.
• Pour in the salt water solution (1 cup of salt per gallon of water).
• Mark bag with field code/date and then check all baggies at the same time at the end of the day.
• 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.
• Holding the baggie up to light helps to see the larvae in the solution
• At the office/lab we can check more carefully by pouring the bag’s contents into a light colored shallow tray and use a piece of wire mesh screen to hold the fruit down making it easier to separate and see the larvae.
• The smaller the larvae and the lighter the infestation, the more difficult to see the larvae.

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.

Jackson County:
(Off Station)
Strawberries (3): 6 males/14 females.
Cherries (4): 4 males/34 females.
Blueberries (2): 2 males/21 females.
Caneberries (1): no males/2 females.
Peaches (3): no males/19 females.
Wild Blackberries (2): 3 males/12 females.
Wine Grapes (3): none.
Garden (1): no males/2 females.


Fig (1) (not checked this week numbers for week before): 20 males/69 females.
Table grape (1): none.
Pears (1): no males/1 female.
Wild Blackberries-fence row (1): 3 males/12 females.
Wild Blackberries-riparian (1): 13 males/18 females.

Lane County:
Strawberries (1): none.
Cherries (2): no males/1 female.
Wild blackberries (5): none.

Linn County:
Strawberries (6): none.
Blueberries (37): 1 male/5 females.
Raspberries (5): none.
Honeysuckle (1): none.

Marion County:
Strawberries (13): 1 male/3 females.
Cherries (3): none.

Clackamas County:
Strawberries (2): none.
Tayberries (1): none.
Honeysuckle (1): none.

Yamhill County:
Strawberries (8): none.
Cherries (3): no males/3 females.

Strawberries (1): none.
Blueberries (2): none.

Multnomah County:
Strawberries (5): none.
Cherries (1): none.
Raspberries (5): none.
Blueberries (2): none.
Blackberries (1): none.
Salmonberries (3): none.

Southwest Washington Public Scouting Program

Clark/Cowlitz/Lewis Counties:
Strawberries (7): 1 male/no females.
Cherries (2): none.
Blueberries (10): none.
Raspberries (30): no males/4 females.
Blackberries (5): none.

Eastern Washington

• One SWD adult was picked up in Yakima and another in Finley, neither were from berry crops.
Click here for the WSU Eastern Washington SWD reporting site. Latest report from the WSU site: “Monday, June 27: Three regions have now caught flies, although numbers are very low. Expect more regions to have first capture in the next few weeks. With (cherry) harvest underway in some of the earlier areas, most of the later areas are close to, if not at, the susceptible stage for attack (blush). Continue cherry fruit fly control in the meantime even if your area has not yet caught flies.

Northern Washington

• An industry fieldman reports a suspected SWD female was recovered from a trap near a strawberry field.

Western British Columbia

• From the July 3rd B.C. Blueberry IPM Newsletter: “ No SWD flies were caught in the 28 Fraser Valley blueberry fields monitored this week. No sprays are recommended for SWD at this time.”

Featured Information Resource

Spotted Wing Drosophila in Western Washington
WSU-Mt. Vernon NW Research Center
• Some of their information resources, among many:
o SWD Biology
o SWD Monitoring & trapping
o Caneberry Management recommendations (last updated 5-26-11)
o Blueberry management recommendations (last updated 5-26-11)
o Strawberry management recommendations (last updated 5-26-11)
o Additional resources