SWD Update 2 August 2011

Publication Date: 
SWD 08-02-11ajd.pdf38.69 KB

Spotted Wing Drosophila Update for 8-2-11

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


We’re at a critical stage when the risk of economic losses from this pest has greatly increased.

• As anticipated, the last 7-10 days has seen a big increase in SWD adult trap counts and detections of larvae in untreated soft fruit. The preliminary degree-day model for predicting SWD activity using temperature showed 50% eggs laid from 1st generation flies occurred on August 1st, 2011.
• Western Oregon and SW Washington have seen the greatest increases. This coming week could see a similar increase further north.
• The highest counts and pressure are being found in caneberries but blueberries are also seeing more and higher trap counts.
• The protocols for checking fruit for larvae are listed below. Many growers and processors have now implemented these to maintain fruit quality.
• Be prepared. Be conservative & pro-active. If you or your neighbors had SWD pressure last year, take all reasonable precautions to minimize the risk this insect poses to your crop.

General Comments

• Commercial growers, in general, have been adhering to a spray regime that so far has prevented any major losses, and they have very low trap counts.
• Some fresh market, u pick, and home gardeners have verified infestations and fruit losses to varying degrees.
• It is strongly recommended that growers with fruit coloring and/or harvesting have a SWD management program in place that includes both fruit sampling for larvae and regular control applications.
• Increases in adult trap counts, incidences of larval infestations, and the levels of those infestations are all anticipated from now through the end on the season.
• 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.

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. Some fruit will float, some with sink The salt solution recipe 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 in other regions

• (Michigan) First SWD trapped in a commercial fruit crop ( 8/1, MSU News)
• SWD has now been detected in 7 states: PA, NJ, NC, SC, LA, MI, UT.

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, Josephine, Douglas Counties: No report this week.
Lane County: Strawberries (1): no males/1 female. Cherries (2): 5 males/11 females. Raspberries (1): none. Blackberries (2): no males/5 females.
Linn County: Strawberries (11): 9 males/4 females. Cherries (2): 37 males/ 15 females. Raspberries (6): 2 males/2 females. Blackberries (7): 8 males/10 females. Blueberries (17): 3 males/4 females. Peaches (4):no males/1 females. Honeysuckle (1): no males/1 female. Plum (2): 6 males/1 females. Wild Habitat (20): 78 males/41 females.
Benton County: Cherries (2): 6 males/6 females. Raspberries (1): none. Peaches (3):3 males/2 females. Wild Habitat (4): 4 males/no females.
Polk County: Blackberries (5): none.
Marion County: Strawberries (1): none. Cherries (3): 4 males/3 females. Blackberries (4): none. Blueberries (6): no males/2 females. Peaches (1):2 males/2 females.
Clackamas County: Strawberries (2): 2 males/1 females. Raspberries (2): 2 males/no females. Blackberries (2): none. Blueberries (7): 2 males/1 females. Tayberries (1): 1 male/1 female. Honeysuckle (1): 8 males/1 female.
Yamhill County: Cherries (4): none. Blackberries (5): 1 male/2 females. Blueberries (1): none.
Washington: Cherries (1): none. Blueberries (4): none.
Multnomah County: Cherries (1): 3 males/5 females. Raspberries (3): no males/2 females. Blackberries (3): 1 male/no females. Blueberries (2): no males/1 female. Boysenberries (1): none.

Southwest Washington Public Scouting Program
Clark/Cowlitz/Lewis Counties: Cherries (2): 6 males/4 females. Raspberries (28): 18 male/10 females. Blackberries (6): no males/2 females. Blueberries (33): none.

Eastern Washington--WSU Reporting Site
Click here for the WSU Eastern Washington SWD reporting site.
• Most recent post on the WSU site: Tuesday, 2 August: "We all know we are having a late year in terms of fruit maturity; the same is true for insect development. As a basis for comparison, we had caught 277 SWD by this time in 2010; this year we have only caught 28 to date. It is likely that cherry growers have a much tighter spray program in 2011; this may also be contributing to low trap captures.”

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.
Whatcom County

• From Colleen Burrows, WSU Agriculture Special Projects Coordinator, (Tuesday, August 2) “We finally found our first SWD here in Whatcom County (a male). We have 85 traps in 40 fields with 18 farmers. There were a few suspicious SWD catches in the past few weeks, but had them confirmed negative by Bev Gerdeman.”
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 7/26/11 SWD Monitoring Report for Southwestern BC from the BC Ministry of Ag.

Management Material Resources

Oregon & Washington
See PNW Insect Management Handbook 2011 for information on SWD.
• 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)