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UMaine Cooperative Extension: Insect Pests, Ticks and Plant Diseases


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Spotted Wing Drosophila 2012 Season Summary for Maine Berry Growers

For full page print version, please see link at the bottom.  Click on photos to enlarge.

David Handley, Vegetable & Small Fruit Specialist; James Dill, Pest Management Specialist; Kaytlin Woodman, Technician, University of Maine Cooperative Extension

In the fall of 2011 we captured spotted wing drosophila flies for the first time in Maine.  Based on crop damage experienced by southern growers in 2010 and 2011, we knew that this insect posed a serious threat to most of the berry crops we grow here.  As part of the University of Maine Cooperative Extension Pest Management Program, we set up drosophila traps in berry fields around the southern, central and coastal regions of the state.  The traps were simply plastic cups with lids mounted on stakes with 16, 1/8” holes punched under the rim to allow the flies access.  Four ounces of bait (a mixture of cider vinegar, white grape juice and alcohol) was poured into each trap.  We placed traps both within the crops and in the wooded areas near the crops, knowing the insect prefers humid, shaded areas.  We emptied the traps weekly and restocked them with fresh bait.  We were hoping the traps would show us when this new pest would start emerging in Maine, and how rapidly populations would build to damaging levels.

The first spotted wing drosophila were caught in Limington on July 13.  By the following week, we had trapped drosophila flies in Springvale, New Gloucester, Poland Spring, Mechanic Falls, Wales, Litchfield, Fayette, Thorndike and Warren.  By August 13, we had captured flies at all of our monitoring locations, adding Buxton, Bowdoinham, Dresden, Turner, Farmington, and Fayette to the list.  During the same week, traps in wild blueberry fields in Hancock and Washington counties were also catching the flies.  In late August trap counts rose dramatically at most locations.  Raspberry and blueberry fruit infested with the small white larvae were being reported, and we received numerous calls about soft, rotting fruit.  Trap counts continued to rise through mid-September, with catches in some locations exceeding 2,000 flies per week. At this point flies were readily visible around ripe fruit in many fields and larvae were found infesting most of the fruit in any plantings that had not been sprayed.  Populations were highest in the southernmost and coastal regions, but relatively high numbers of flies were caught in nearly all locations at some point in the season.

Growers who were using insecticides to control spotted wing drosophila initially found that weekly sprays appeared to provide adequate control.  However, as fly populations expanded, growers found that twice weekly sprays were needed to keep larvae out of the fruit.  Growers were using Entrust®, Delegate®, Brigade®, Mustang Max®, and/or malathion insecticides, and most found that these products usually offered adequate control if applied on a frequent basis.  Some growers who did not apply pesticides reported total crop loss following the arrival of spotted wing drosophila in their fields.

Spotted Wing Drosophila Trap Captures in Maine, 2012

Spotted Wing Drosophila Trap Captures in Maine 2012 Data (Excel)

Spotted wing drosophila trap catches remained relatively high throughout the remainder of the season, with a slight dip in late September, which may correlate with a dry spell (we are still analyzing weather data).  In fact, some of the highest trap catches occurred late in the season, in early November, well after most of the crops had been harvested or lost to frost.  The lack of food may have made the traps more attractive, accounting for the increased catch, but this still indicates that high numbers of flies appear to survive long after killing frosts have occurred.  By the end of November, populations finally dropped significantly, suggesting that the flies were now entering the over-wintering stage.

This species over-winters as adults, and research suggests that they should emerge early in the spring to seek out food and begin breeding and laying eggs.  It is thought that the over-wintering survival rate will be relatively low here, but enough should survive to cause similar, if not greater, problems in 2013, given that they will be starting in higher numbers and be more widely dispersed than they were in 2012.

Thus, berry growers should anticipate needing to manage drosophila for the 2013 season.  Based on this year’s data and records from other states, we believe it will be unlikely to significantly infest crops until relatively late in the season when populations reach damaging levels (this year early to mid-August).  Therefore, earlier ripening crops such as June-bearing strawberries should not be significantly impacted, but later ripening crops such as late summer and fall fruiting raspberries, later varieties of blueberries and fall strawberries will need to be protected as soon as fruit begin to ripen.  We plan to again monitor drosophila populations in Maine in 2013, and carry out research on improving our trapping strategies to provide an early warning system in the future.

If you have not yet filled out a grower survey of how spotted wing drosophila impacted your crops this year, click here.  Your input will greatly help us develop our research and educational efforts for the future.  There is a very good fact sheet series on spotted wing drosophila from the Pennsylvania State University, and we have some free copies available.  Contact Pam St. Peter at 933-2100 or pamela.stpeter@maine.edu.  You can also download a free copy at their website.

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                       Pest Management Office
P.O. Box 179                              491 College Ave
Monmouth, ME  04259        Orono, ME  04473
(207) 933-2100                        1-800-287-0279

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/
http://www.umass.edu/umext/ipm/

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions.  Users of these products assume all associated risks.


Spotted Wing Drosophila Update for Maine Fruit Growers – August 24, 2012

Spotted Wing Drosophila Trap, Male SWD Circled, photo by Kaytlin Woodman

Over the last week and a half, spotted wing drosophila numbers in our traps have increased significantly.  We are now finding both male and female flies in the highest numbers of the season.  In addition, we have found drosophila maggots infesting both highbush blueberry and raspberry fruit this week and have been getting reports from growers around the state of infested fruit.  Some farms have closed berry sales for the season as harvest is coming to an end, and the few fruit remaining will not be worth the extra effort of repeated insecticide sprays to rescue them.  For those with late fruit crops still to harvest, protection will now be necessary to prevent infestation by spotted wing drosophila.  Up to this point weekly applications of an allowed insecticide have been adequate, but reports from the field suggest that more frequent applications will now be necessary to keep fruit free from maggots.  Growers in southern states have found that a three to five-day spray schedule was needed to prevent infestation.

Spotted Wing Drosophila Larva in Blueberry, photo by David Handley

Maine Crisis Exemption Label for Gowan Malathion 8 Flowable® to Control Spotted Wing Drosophila on Blueberries:
There are just a few more days left to utilize the  Section 18 Crisis Exemption granted by the EPA for the use of Gowan Malathion 8 Flowable® at a higher rate than the federal label allows, to provide better control of spotted wing drosophila on blueberries.  This label will allow a rate of 2.0 to 2.5 pt/acre per application, with a maximum of two applications per field.  This exemption rate can only be used from August 13 through August 28 this year.  Growers must have a copy of the exemption label in their possession to use this rate, and must fill out a use survey at the end of the season.  Exemption Labels are available through pesticide dealers, and the Board of Pesticides Control (287-7544).

Check product labels for which crops are registered for the product, application limits, rates, post-harvest intervals and safety precautions.  Keeping the fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect.

We have available a very good series of new fact sheets from Penn State Extension regarding spotted wing drosophila.  If you would like copies please e-mail Pam St. Peter at pamela.stpeter@maine.edu, or call Pam at 933-2100.

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
Monmouth,ME 04259            Orono,ME 04473
(207) 933-2100                     1-800-287-0279

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/
http://www.umass.edu/umext/ipm/

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions.  Users of these products assume all associated risks.


Spotted Wing Drosophila Update for Maine Fruit Growers – August 15, 2012

Male Spotted Wing Drosophila, photo by Griffin Dill. Actual size: 2-3 mm.

During the past week we have seen a significant increase in spotted wing drosophila coming to our traps in southern Maine.  This suggests that the threat of infestation to any soft fruit or berries remaining in the field is now very high.  We are catching these fruit flies in all of the locations where we have placed traps including Limington, Buxton, Springvale, Bowdoinham, Dresden, New Gloucester, Poland Spring, Mechanic Falls, Turner, Farmington, Wales, Litchfield, Fayette, Thorndike and Warren.  In addition, traps in wild blueberry fields in Hancock and Washington counties have caught flies during the past week.  We are confident that the fly is now widespread and active through most, if not all, of the southern, mid-state and coastal regions of the state.  Also, as the quantity of fruit available is reduced through harvesting, pressure on the remaining fruit will intensify.  We recommend protecting any berry crops or other soft fruit with an appropriate insecticide on a frequent and regular schedule.  With fly catches increasing, more frequent spray applications will probably be needed to achieve adequate control.  The table below lists available materials and the estimated days of residual activity, assuming the product is not washed off by heavy rains.

Characteristics of Insecticides for Spotted Wing Drosophila Control

Trade Name Days to Harvest
Blueberry
Days of Residual
Malathion 1 5-7
Mustang Max® 1 7
Brigade® 1 7
Delegate® 3 (1 raspberry) 7
Entrust® 3 (0 raspberry) 3-5
PyGanic® 12 hr 2-3

Please check product labels for which crops are registered for the product, application limits, rates, post-harvest intervals and safety precautions.  Keeping the fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect.

Maine Crisis Exemption Label for Gowan Malathion 8 Flowable® to Control Spotted Wing Drosophila on Blueberries:
Maine has been granted a Section 18 Crisis Exemption by the EPA for the use of Gowan Malathion 8 Flowable® at a higher rate than the federal label allows, to provide better control of spotted wing drosophila on blueberries.  This label will allow a rate of 2.0 to 2.5 pt/acre per application, with a maximum of two applications per field.  The length of this exemption is very short; this rate can only be used from August 13 through August 28 this year.  Growers must have a copy of the exemption label in their possession to use this rate, and must fill out a use survey at the end of the season.  Exemption Labels are available through pesticide dealers, and the Board of Pesticides Control (287-7544).

We have available a very good series of new fact sheets from Penn State Extension regarding spotted wing drosophila.  If you would like copies please e-mail Pam St. Peter at pamela.stpeter@maine.edu, or call Pam at 933-2100.

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
Monmouth,ME 04259            Orono,ME 04473
(207) 933-2100                     1-800-287-0279

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/
http://www.umass.edu/umext/ipm/

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions.  Users of these products assume all associated risks.


Spotted Wing Drosophila Update for Maine Fruit Growers – August 1, 2012

Since our first occurrence of spotted wing drosophila in Limington on July 13, we have now found spotted wing drosophila flies in traps in locations in Springvale, New Gloucester, Poland Spring, Mechanic Falls, Wales, Litchfield, Fayette, Thorndike and Warren.  In the past week additional captures have occurred in Buxton, Bucksport and Franklin, in addition to more captures in the earlier locations.  At this point we assume that the fly is fairly widespread and active through most, if not all, of the southern, mid-state and coastal regions of the state.  We recommend protecting any berry crops or other soft fruit with an appropriate insecticide on a frequent and regular schedule.  At the moment weekly applications appear to be keeping drosophila in check.  However, fly catches in most locations are increasing, so the problem is likely to get worse as the season progresses.  Therefore, more frequent spray schedules will probably be needed to achieve adequate control.

Products that provide good control of Drosophila on berries include spinosad products such as Entrust® and Delegate® (group 5), and pyrethroids such as Brigade®, Mustang Max® and Danitol® (group 3).  Please check product labels for which crops are registered for the product, application limits, rates, post-harvest intervals and safety precautions.  Keeping the fields clean of overripe and rotten fruit can also help reduce the incidence of this insect.

We have recently received a very good series of new fact sheets from Penn State Extension regarding identification, biology, monitoring and management of spotted wing drosophila.  Thanks to a grant from the Northeast IPM Center, we can offer you copies of these fact sheets for free until our supply runs out.  If you would like copies please email Pam St. Peter at pamela.stpeter@maine.edu, or call Pam at 933-2100.

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
Monmouth,ME 04259            Orono,ME 04473
(207) 933-2100                      1-800-287-0279

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/
http://www.umass.edu/umext/ipm/

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions.  Users of these products assume all associated risks.

Spotted Wing Drosophila Management

Trade Name Active Ingredient Preharvest Interval (days)a Effectiveness Length of Residual Activity
    Raspberries Blackberries Strawberries Cherries    
Pyrethroids and Pyrethrins (IRAC Activity Group 3A)
Brigade bifenthrin 3 3 0 X Excellent 7 days
Danitol fenpropathrin 3b 3b 2b 3b Excellent 7 days
Baythroid beta-cyfluthrin X X X 7b Excellent 7 days
Mustang Max zeta-cypermethrin 1b 1b X 14b Excellent 7 days
PyGanicc pyrethrins 0 0 0 0 Goodd 0-2 days
Spinosyns (IRAC Activity Group 5)
Delegate spinetoram 1b 1b X 7b Excellent 5-7 days
Radiant spinetoram X X 1 X Excellent 5-7 days
Spintor spinosad 1 1 1 7 Excellent 5-7 days
Success spinosad 1b 1b 1 7b Excellent 5-7 days
Entrustc spinosad 1b 1b 1 7b Excellent 5-7 days
Organophosphates (IRAC Activity Group 1B)
Malathion malathion 1 1 3 3 Excellent >7 days
Diazinon diazinon X X 5 21 Excellent >7 days

a.   “X” = the material is not labeled for use on the crop.
b.   2(ee) labels have been issued for use against SWD on this crop.
c.   May be used in organic production.  For PyGanic, the REI is 12 hours even though the PHI is 0 days.
d.   Provides knockdown of nonresistant populations but has little or no residual activity.
From Penn State Extension “Spotted Wing Drosophila, Part 4: Management.”  http://extension.psu.edu/fruit-times/news/2012/spotted-wing-drosophila-fact-sheets-completed-and-on-line.


 

Spotted Wing Drosophila Update for Maine Fruit Growers – July 23, 2012

Male Spotted Wing Drosophila, photo by Griffin Dill. Actual size: 2-3 mm.

The first spotted wing drosophila of the 2012 season was found in a trap in Limington on Friday, July 13.  Since that time, we have found spotted wing drosophila flies in our traps at locations in Springvale, New Gloucester, Poland Spring, Mechanic Falls, Wales, Litchfield, Fayette, Thorndike and Warren.  While we have not yet caught the flies at all of the locations where we are trapping, it would be best to assume that the fly is now fairly widespread and active through much of the state.  Therefore, if you presently have ripening berry crops or other soft fruit, we are recommending protecting them with an appropriate insecticide on a regular basis at this time.  We are catching relatively low numbers of flies at these locations but the numbers have started to increase.  We know that the traps only tell us when the fly is already in the field, and we also know how rapidly the population can explode, so we are recommending preventive measures be taken as soon as possible.

Products that provide good control of drosophila on berries include spinosad products such as Entrust®, Radiant® and Delegate® (group 5), and pyrethroids such as Brigade®, Mustang Max® and Danitol® (group 3).  Please check product labels for which crops are registered for the product, rates, post-harvest intervals and safety precautions.  Keeping the fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect.

Male and Female Spotted Wing Drosophila, image by Alan Kenage, Capital Press

For information on identifying spotted wing drosophila and making your own monitoring traps, visit the Michigan State University’s Spotted Wing Drosophila website.  There is also a good fact sheet on management of spotted wing drosophila on the Penn State Extension website.

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                         Pest Management Office
P.O. Box 179                            491 College Ave
Monmouth, ME  04259              Orono, ME  04473
(207) 933-2100                         1-800-287-0279

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/
http://www.umass.edu/umext/ipm/

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions.  Users of these products assume all associated risks.


Fruit Growers Alert: Spotted Wing Drosophila has been found in Maine!  July 13, 2012

The first spotted wing drosophila of the 2012 season was found in a trap in Limington on Friday, July 13.  Three male flies were caught in a trap in the woods adjacent to a raspberry planting.  We haven’t caught flies in other locations yet, but growers should be on alert for indications of fruit flies in their plantings and premature fruit decay.

Spotted wing drosophila (Drosophila suzukii) is a new pest which is a concern for raspberries, blueberries and day neutral strawberries, as well as many other soft fruits.  This insect is a small fruit fly, similar to the type that flies around the over-ripe bananas in your kitchen.  However, this species will lay its eggs on fruit before it ripens, resulting in fruit that is contaminated with small white maggots just as it is ready to pick.  As a result, the fruit quickly rots and has no shelf life.  This insect recently came into the U.S. from northern Asia, and caused problems with many berry crops up the east coast last year.  It can complete a generation in under two weeks, with each adult female laying hundreds of eggs.  Therefore, millions of flies can be present soon after the introduction of just a few into a field.  This makes them very difficult to control, and frequently repeated insecticide sprays (3 to 5 times per week) may be needed to prevent infestations once the insect is present in a field.  It is likely that spotted winged drosophila can successfully overwinter here, although it may not build up to damaging levels until summer.  We have set out monitoring traps for spotted winged drosophila in fruit plantings around the state to determine the activity of this pest in Maine.  However, these traps are unlikely to provide early warning, i.e. when we find them in a trap they are probably already established in the field.  We will be alerting growers when we find them in Maine.  Now that spotted wing drosophila has been confirmed in a berry planting in southern Maine, growers should be on the alert and look for fruit flies on their fruit and symptoms of premature fruit decay.  Products that provide good control of drosophila on berries include Delegate®, Brigade®, Danitol®, and malathion.  Please check product labels for rates, post-harvest intervals and safety precautions.  Keeping the fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect.  For information on identifying spotted wing drosophila and making your own monitoring traps, visit the Michigan State University’s Spotted Wing Drosophila website.  There is also a good fact sheet on management of spotted wing drosophila on the Penn State Extension website.

David T. Handley, Ph.D.
Vegetable & Small Fruit Specialist

University of Maine Cooperative Extension
Highmoor Farm
P.O. Box179
Monmouth, ME  04259-0179
Tel. (207) 933-2100
Fax 207-933-4647
david.handley@maine.edu

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/
http://www.umass.edu/umext/ipm/

Where brand names or company names are used it is for the reader’s information.  No endorsement is implied nor is any discrimination intended against other products with similar ingredients.  Always consult product labels for rates, application instructions and safety precautions.  Users of these products assume all associated risks.

Image Description: Print Friendly

Image Description: Spotted Wing Drosophila Trap Captures in Maine, 2012

Image Description: Spotted Wing Drosophila Trap with One Male SWD Circled

Image Description: Spotted Wing Drosophila Maggot in Blueberry

Image Description: Male Spotted Wing Drosophila

Image Description: Male and Female Spotted Wing Drosophila Flies

Image Description: Male Spotted Wing Drosophila

Image Description: Male and Female Spotted Wing Drosophila Flies

Image Description: Male and Female Spotted Wing Drosophila


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University of Maine Cooperative Extension


Contact Information

UMaine Cooperative Extension: Insect Pests, Ticks and Plant Diseases
491 College Avenue
Orono, Maine 04473-1295
Phone: 207.581.3880, 800.287.0279 (in Maine) or 800.287.8957 (TDD)E-mail: extension@maine.edu
The University of Maine
Orono, Maine 04469
207.581.1110
A Member of the University of Maine System