SWD Update 26 July 2011

Publication Date: 
SWD 07-26-11ajd.pdf38.78 KB

Spotted Wing Drosophila Update for 7-26-11

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 greatly increases


• Last year at this point we saw an increase of 300% in trap catches. Assuming we’re running one to two weeks behind last year, we should expect a similar increase soon.
• Most of the trap increase both years in the Oregon and SW Washington survey has come in raspberry and blackberry fields, but the increase was seen across the board.
• Both 2010 and 2011 data indicates that there is a very real correlation to adult trap catches and an actual increase in larval infestation of the fruit.
• 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.
• Last year mid to late July was the window of time in which we saw a dramatic increase in SWD pressure on all west side berry crops from Northern California into the Fraser Valley in B.C. Numbers of females shifted from 80-90% to 40% females.
• Conventional commercial growers, in general, have been adhering to a spray regime that so far has prevented any major losses and have very low trap counts
• However some organic growers as well as some fresh market, u pick, and home gardeners have verified infestations and fruit losses to varying degrees.
• As blueberry and caneberry fields finish harvest, a post harvest insecticide treatment is recommended in some cases, to prevent the field from harboring a breeding population of SWD. Focus on directly treating the crop at risk.
• 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.
• 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 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 in other regions

Fruit pest found in Virginia (7/23, Carroll County Press)
• (North Carolina) Summer Spotted Wing Drosophila update (7/24, Hannah Burrack’s blog NC Small Fruit IPM Blog)
• (Ontario, Canada) SWD Update for 7/20

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): 12 males/6 female. Raspberries (1): none. Blackberries (2): none.
Linn County: Strawberries (10): 8 males/1 female. Raspberries (6): none. Blackberries (7): 8 males/6 females. Blueberries (13): no males/1 female. Peaches (4):2 males/no females. Honeysuckle (1): none. Plum (2): 9 males/3 females. Wild Habitat (20): 48 males/14 females.
Polk County: No trap data reported.
Marion County: Strawberries (2): none. Cherries (3): 3 males/ no females. Blackberries (6): 2 males/6 females. Blueberries (9): none.
Clackamas County: Strawberries (1): 3 males/no females. Raspberries (1): none. Blackberries (1): none. Blueberries (7): no males/1 females. Tayberries (1): none. Honeysuckle (1): 2 males/no females.
Yamhill County: Cherries (6): none. Blueberries (1): none.
Washington: Cherries (1): none. Blueberries (2): none.
Multnomah County: Strawberries (1) no males/1 females. Cherries (1): 6 males/3 females. Raspberries (2): none. Blackberries (5): none. Blueberries (2): no males/1 female. Boysenberries (1): none. Salmonberries (1): no males/1 female.

Southwest Washington Public Scouting Program
Clark/Cowlitz/Lewis Counties: Strawberries (5): 7 males/5 females. Cherries (2): 6 males/1 female. Raspberries (26): 1 male/1 female. Blackberries (6): 1 male/1 female. Blueberries (23): none.

Eastern Washington--WSU Reporting Site
Click here for the WSU Eastern Washington SWD reporting site.
• Most recent post on the WSU site: Friday, 15 July: “There has been a new regional find today of SWD, in the Brewster area. One male. This find was from a private trap, and many thanks to the folks willing to share their information and alert growers in their area. Five regions now have positive catches.”

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 7/26/11 SWD Monitoring Report for Southwestern BC from the BC Ministry of Ag.
• From the editor of the B.C. Blueberry IPM Newsletter: “SWD flies were caught at two blueberry sites this week. In Langley, one female was caught. In Pitt Meadows, one male SWD was caught.”

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)

Pesticide tank mixes caution
In an effort to manage the risk involved with this new pest, some growers are using combinations of pesticides that they have not used in the past. Before applying an unfamiliar tank mix, be sure to check with your supplier, crop consultant, or other advisor to be sure it won’t cause damage. Some mixes have the potential for unexpected, economically damaging effects—just the thing we’re trying to avoid by using them.