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Fruit Growers Alert 7/19/13: Spotted Wing Drosophila Counts are Rising

Fruit Growers Alert – July 19, 2013

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

SPOTTED WING DROSOPHILA COUNTS ARE RISING

Spotted wing drosophila flies were captured in traps in Warren (6 males, 3 females) and Wells (2 females) this week in a strawberry field and raspberry field, respectively. These trap captures indicate that this insect is becoming more active in Maine. Last week we had low numbers caught in wild blueberry fields in Winterport, Whitefield and Dresden. Although the numbers are still quite low, and don’t pose an immediate threat to berry crops, populations are expected to increase in the coming weeks to damaging levels.  Research and Extension staff in Connecticut, Massachusetts, New Hampshire and New York are all reporting increasing numbers of spotted wing drosophila in traps over the past week, and one grower in Massachusetts claims to have found larvae in recently harvested fruit, although this is unconfirmed.

At this point in the season, spotted wing drosophila will pose the greatest threat to raspberries, blueberries and any other soft fruit that is beginning to ripen. They are able to lay eggs in fruit as soon as it starts to color. Spotted wing drosophila can complete a generation in less than two weeks and, with each adult female laying hundreds of eggs, populations can explode rapidly when conditions are right. Last year populations did not reach damaging levels until late August, but weather conditions can alter how quickly the flies will build up. Frequently repeated insecticide sprays (1 to 3 times per week) may be needed to prevent infestations once the insect is present in a field. Growers should now 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®, Bifenture®, Danitol®, Mustang Max®, malathion and Assail®. Research carried out at the Connecticut Agricultural Experiment Station suggests that adding table sugar to group 4A insecticides such as Assail®, may improve their effectiveness. The recommended rate would be 1-2 lbs. sugar per 100 gallons of spray. 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 series on Management of Spotted Wing Drosophila from Penn State on their website.

Highmoor Farm Field Day
Please join us for the Highmoor Farm Field Day and Summer Tour to be held on Wednesday, July 31, starting at 9:00 a.m. Growers will have an opportunity to tour the fruit and vegetable research plots at the farm, part of the Maine Agricultural and Forest Experiment Station, and hear Extension specialists and guest speakers discuss current research on apples, grapes and vegetables. Maine State Legislators will also be on hand to offer updates on programs and legislation effecting farming in Maine.  Please join us for the program, farm tours and lunch. Visit the Field Day website for more information.

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                       Pest Management Office
P.O. Box 179                             491 College Avenue
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/sweet_corn.htm
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: Spotted Wing Drosophila Larvae in Raspberry

Image Description: Spotted Wing Drosophila Larvae in Blueberry

Fruit Growers Alert 7/9/13: Spotted Wing Drosophila Has Been Found In Maine!

Fruit Growers Alert – July 9, 2013

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

SPOTTED WING DROSOPHILA HAS BEEN FOUND IN MAINE!

David Handley, Vegetable & Small Fruit Specialist; James Dill, Pest Management Specialist; Frank Drummond, Professor of Insect Ecology/Entomology

Male spotted wing drosophila flies were captured in traps in Dresden and Whitefield on July 3rd in wild blueberry fields. On Saturday, July 6th, a male fly was caught in a Winterport blueberry field. We have traps set out in raspberry and highbush blueberry fields in southern and central Maine, but have not yet captured any spotted wing drosophila in those fields.    However, the presence of spotted wing drosophila in the wild blueberry fields indicates that this insect is now becoming active in the state, slightly earlier than our first captures last year.  Research and Extension staff in Connecticut, Massachusetts, New Hampshire and New York have all reported captures of spotted wing drosophila over the past two weeks, although in all cases the numbers have been low.

Raspberries before and after infestation, 48 hours at room temperature after picked.

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 fly 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 first came into Maine in 2011, and caused significant losses in raspberry and blueberry plantings last year.  Spotted wing drosophila can complete a generation in less than two weeks, with each adult female laying hundreds of eggs, so populations can explode rapidly when conditions are right.  This makes them very difficult to control, and frequently repeated insecticide sprays (1 to 3 times per week) are often needed to prevent infestations once the insect is present in a field.  It appears that spotted winged drosophila can successfully overwinter here, although it has not been able to build up to damaging levels until late summer. June-bearing strawberries and early ripening varieties of raspberries and blueberries may escape infestation, but later ripening varieties and everbearing types of strawberries and raspberries will likely become infested if they are not protected. Now that spotted wing drosophila has been confirmed in 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®, Bifenture®, Danitol®, Mustang Max®, malathion and Assail®. Research carried out at the Connecticut Agricultural Experiment Station suggests that adding table sugar to group 4A insecticides such as Assail®, may improve their effectiveness. The recommended rate would be 1-2 lb. sugar per 100 gallons of spray.   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 series 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 Avenue
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/sweet_corn.htm
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: Male and Female Spotted Wing Drosophila Flies

Image Description: Fall Raspberries

Image Description: Spotted Wing Drosophila Emerging from Fall Raspberries

Press Herald Interviews Handley, Kirby on Garden Insects

The Portland Press Herald spoke with David Handley, a vegetable and small-fruit specialist with the University of Maine Cooperative Extension in Monmouth, and Clay Kirby, an insect diagnostician with the UMaine Cooperative Extension in Orono, about bugs in the garden. The pair spoke about this season’s likely pests.

UMaine Extension Pest Specialists Find Spotted Wing Drosophila Problematic in State

University of Maine Cooperative Extension pest management specialists tracking the invasion of the crop-damaging spotted wing drosophila fruit fly in Maine report that trapping results and surveys indicate that the pest has already become established and problematic in most of the state.

UMaine Extension experts David Handley, a vegetable and small fruit specialist at Highmoor Farm in Monmouth, and James Dill, a pest management specialist in Orono, have been setting and checking flytraps statewide to catch the fruit flies and assess their incidence. They also are analyzing survey data from farmers who are assisting with the assessment.

“We were still catching high numbers of fruit flies into November, but the numbers have dropped pretty steeply over the past two weeks, probably due to the colder temperatures and lack of food,” says Handley. “Any farm we set a trap at, we caught these flies, often in very high numbers — thousands — which is pretty impressive when you consider that they first arrived in Maine last fall.”

Handley and Dill had traps set up at berry farms from Wells to Orono, and Frank Drummond, professor of entomology at the University of Maine, had numerous traps in wild blueberry fields in the Down East region.

Most fruit and berry growers noticed fruit flies on their crops, especially later in the summer, but most did not see high levels of damage from the larvae if they controlled the adults. Where the adults were not controlled, most of the late season fruit contained larvae, causing it to rot prematurely.

The spotted wing drosophila originated in Asia and traveled in fruit and vegetable imports to California. In the past three years, the invasive pest has spread up and down both coasts and into the Midwest. The small flies resemble common fruit flies except for a saw-like appendage on the female’s ovipositor used to bore into the soft skin of fruits like blueberries and raspberries to lay eggs. The white larvae feed on the fruit from the inside, destroying it in the process. Common fruit flies must wait until fruit gets overripe before they can lay eggs in it.

Maine growers and agricultural scientists fear the invasion of the spotted wing drosophila could devastate soft fruit crops, particularly if growers are trying to avoid chemical pesticides to control insects. So far, frequent applications of pesticides appear to be the only effective way to control the tiny flies, according to Dill.

“The good news is that we have pesticides that will control them pretty well, including some materials that are available for organic farmers,” he says. “The bad news is that frequent applications are needed because of the vast numbers of flies that are continually invading the crop.”

Contact: George Manlove, 207.581.3756

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 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 207.933.2100 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

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.

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 207.933.2100.

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

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 207.933.2100.

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 207.933.2100.

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

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.

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: 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

Sweet Corn IPM Newsletter No. 8 – August 1, 2012

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

CORN EARWORM PRESSURE INCREASES IN SOUTHERN MAINE

European Corn Borer and Fall Armyworm Threat Remains Small

SITUATION
Harvest is still spotty as growers work through the erratic early corn and hope for better uniformity and quality with the main season crop.  Many fields received just enough rain to get a break from irrigation this week.  A little bit of weather coming up from the southeast coast appears to have bumped up local corn earworm populations, so silking corn is likely to need protection, especially in the southern and coastal areas of the state.

European corn borer:  Moth counts were higher in some northern locations this week, requiring protection of silking corn, but remained low in most southern fields.  Charleston, Levant, Palmyra and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn remained low in most locations this week, only exceeding the 15% feeding injury threshold in Cape Elizabeth and Poland Spring.

Corn earworm:  A significant increase in moth activity over the past two nights has increased the number of fields needing to protect any fresh silking corn.  A 4-day spray interval was recommended in one Cape Elizabeth location and North Berwick.  A 5-day spray interval was recommended for Biddeford, a second Cape Elizabeth location, Monmouth and New Gloucester.  A 6-day spray interval was recommended for fields in Lewiston,Warren and Wells.  Fields in Dayton, Jefferson, Palmyra, Poland Spring and Sabattus caught single moths, which does not warrant a spray.

Fall armyworm:  Two fall armyworm moths were caught in one Cape Elizabeth location this week.  This is below threshold for silking corn.  No feeding damage was found.

Spotted wing drosophila update:  The numbers and range of the “Suzuki Fruit Fly” continue to increase around the state.  We have found this small fruit fly in traps in Limington, Buxton, Sanford, New Gloucester, Mechanic Falls, Poland Spring, Wales, Litchfield, Fayette, Thorndike, Warren and Bucksport.  This week also saw the first capture of this fly in a wild blueberry field in Franklin.  Berry growers need to be on the alert for fruit flies and symptoms of premature fruit decay.  Have your pickers keep fields free of overripe fruit.  At this point, insecticide sprays every 5-7 days appears to provide adequate control.  More frequent sprays may become necessary as populations increase.  There is a good fact sheet about the management of spotted wing drosophila on the Penn State Extension website.

Corn rust causes reddish-brown pustules to form on the leaves, stalks and husks, reducing the visual quality of the ears.  We see more of this problem in wet, humid seasons.  Some varieties are resistant.  Severe infections can reduce ear size, especially if they occur prior to tassel.  A fungicide spray for rust is only recommended if the infection occurs prior to tasseling.  Later infections are unlikely to cause enough damage to the crop to justify control measures.  Materials available to control corn rust include Bravo®, Quilt® and maneb/mancozeb.

Sincerely,

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

Sweet Corn IPM Weekly Scouting Summary

 Location CEW Moths ECB Moths FAW Moths % ECB Damage Recommendations / Comments
 Biddeford  7  3  0  4% 5-day spray interval for all silking corn
 Cape Elizabeth I  11  0  2  0% 4-day spray interval for all silking corn
 Cape Elizabeth II  6  0  0  21% 5-day spray interval for all silking corn
 Charleston  0  9  0  1% One spray recommended for ECB on silking corn
 Dayton I  1  1  0  3% No spray recommended
 Dayton II  1  0  0  1% No spray recommended
 Dresden  0  1  0  5% No spray recommended
 East Corinth  0  20  0  0% One spray recommended for ECB on silking corn
 Farmington  0  0  0  2% No spray recommended
 Jefferson  1  0  0  7% No spray recommended
 Levant  0  8  0  6% One spray recommended for ECB on silking corn
 Lewiston  2  1  0  0% 6-day spray interval for all silking corn
 Lewiston II  2  3  0  9% 6-day spray interval for all silking corn
 Monmouth  6  2  0  7% 5-day spray interval for all silking corn
 New Gloucester  5  0  0  2% 5-day spray interval for all silking corn
 North Berwick  8  0  0  1% 4-day spray interval for all silking corn
 Oxford  0  0  0  8% No spray recommended
 Palmyra  1  6  0  5% One spray recommended for ECB feeding
 Poland Spring  1  3  0  30% One spray recommended for ECB feeding
 Sabattus  1  1  0  8% No spray recommended
 Wales  0  0  0  13% No spray recommended
 Warren  3  0  0  7% 6-day spray interval for all silking corn
 Wells I  3  0  0  0% 6-day spray interval for all silking corn
 Wells II  3  0  0  1% 6-day spray interval for all silking corn

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB:  European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

 Moths caught per week  Moths caught per night  Spray interval
 0.0 to 1.4  0.0 to 0.2  No spray
 1.5 to 3.5  0.3 to 0.5  Spray every 6 days
 3.6 to 7.0  0.6 to 1.0  Spray every 5 days
 7.1 to 91  1.1 to 13.0  Spray every 4 days
 More than 91  More than 13  Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage:  30% or more of plants scouted show injury.
Pre-tassel-silk:  15% or more of plants scouted show injury.
Silk:  5 or more moths caught in pheromone traps in one week.

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Image Description: Sweet Corn

Image Description: European Corn Borer Moth

Image Description: Corn Earworm Moth

Image Description: Male Spotted Wing Drosophila

Image Description: Male and Female Spotted Wing Drosophila

Image Description: Rust on Corn

Sweet Corn IPM Newsletter No. 7 – July 25, 2012

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

CORN PEST ACTIVITY REMAINS LOW IN MOST LOCATIONS

Western Bean Cutworm Found in Maine Corn Fields

SITUATION
Early harvest is getting into full swing and corn quality is looking good, although ear size has been a bit small due to dry conditions in some areas.  Moth counts continue to be very low for this time of year, but nobody is complaining.

European corn borer:  Moth counts were very low in southern locations this week, but some northern sites continue to have enough moths flying to warrant protection of silking corn.  Three sites, Charleston, Levant and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn was also less prevalent this week, only exceeding the 15% feeding injury threshold in Biddeford, Jefferson, Poland Spring and Sabattus.

Corn earworm:  There was a slight increase in moth activity in a few locations this week.  A 6-day spray interval for fresh silking corn was recommended for fields in Nobleboro, North Berwick, Palmyra, and Poland Spring.  Three locations had only single moths, which don’t warrant a spray.  Most locations had no moths.

Fall armyworm:  No fall armyworm moths were caught this week and no feeding damage was found in the field.

Western bean cutworm:  A new corn pest for Maine?
We set out pheromone traps for western bean cutworm in cornfields this spring, based on reports that this insect is becoming a problem in corn in the upper Midwest and mid-Atlantic regions.  We have caught a few moths in Wells, Cape Elizabeth and New Gloucester over the past couple weeks, and we’re now evaluating what level of risk these present.  The larvae of western bean cutworm will feed on corn plants and move into the ears either through the silk channel or through the husks.  Unlike corn earworm, they are not cannibalistic; so many larvae may be found in a single ear, feeding on the kernels.  The threshold for feeding injury on plants is 8%.  There isn’t an established threshold for moths laying eggs in silking corn yet, but plants that are already on a spray program for corn earworm should also be protected from western bean cutworm.

Spotted wing drosophila update:  We have found this “new” fruit fly in more locations and in higher numbers this week, threatening raspberries, blueberries and any other soft fruit that is available.   We have now caught this fly in traps in Limington, Sanford, New Gloucester, Mechanic Falls, Wales, Litchfield, Fayette, Thorndike, and Warren.  Growers should be on the alert and look for fruit flies on their fruit and symptoms of premature fruit decay.  At this point, keeping fields free of overripe fruit and weekly insecticide sprays appear to be keeping this pest in check.  However more frequent sprays may become necessary as pest populations increase.  There is a good fact sheet on management of spotted wing drosophila on the Penn State Extension website.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      PestManagement Office
P.O. Box179                          491 College Ave
Monmouth,ME 04259            Orono,ME 04473
207.933.2100                        1.800.287.0279

Sweet Corn IPM Weekly Scouting Summary

 Location CEW
Moths
ECB
Moths
FAW
Moths
%ECB
Damage
Recommendations / Comments
 Biddeford  0  0  0  30% One spray recommended for ECB feeding
 Cape Elizabeth I  0  0  0  6% No spray recommended
 Cape Elizabeth II  0  0  0  10% No spray recommended
 Charleston  0  5  0  1% One spray recommended for ECB on silking corn
 Dayton I  0  0  0  0% No spray recommended
 Dayton II  1  0  0  0% No spray recommended
 Dresden  0  0  0  9% No spray recommended
 East Corinth  0  6  0  0% One spray recommended for ECB on silking corn
 Farmington  0  1  0  3% No spray recommended
 Jefferson  0  0  0  19% One spray recommended for ECB feeding
 Levant  0  5  0  5% One spray recommended for ECB on silking corn
 Lewiston  0  0  3% No spray recommended
 Lewiston II  0  0  0  13% No spray recommended
 Livermore Falls  1  0  0  1% No spray recommended
 Monmouth  0  1  0  0% No spray recommended
 New Gloucester  0  0  0  2% No spray recommended
 Nobleboro  2  0  0  0% 6-day spray interval for all silking corn
 North Berwick  2  0  0  0% 6-day spray interval for all silking corn
 Oxford  0  1  0  5% No spray recommended
 Palmyra  2  3  0  3% 6-day spray interval for all silking corn
 Poland Spring  2  0  0  21% 6-day spray interval for all silking corn
 Sabattus  0  0  0  23% One spray recommended for ECB feeding
 Wales  0  0  0  0% No spray recommended
 Warren  0  0  0  0% No spray recommended
 Wells I  1  0  0  0% No spray recommended
 Wells II  0  1  0  6% No spray recommended

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB:  European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

 Moths caught per week  Moths caught per night  Spray interval
 0.0 to 1.4  0.0 to 0.2  No spray
 1.5 to 3.5  0.3 to 0.5  Spray every 6 days
 3.6 to 7.0  0.6 to 1.0  Spray every 5 days
 7.1 to 91  1.1 to 13.0  Spray every 4 days
 More than 91  More than 13  Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage:  30% or more of plants scouted show injury.
Pre-tassel-silk:  15% or more of plants scouted show injury.
Silk:  5 or more moths caught in pheromone traps in one week.

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Image Description: Sweet Corn

Image Description: European Corn Borer in Tassel

Image Description: Corn Earworm Moth

Image Description: Male and Female Spotted Wing Drosophila Flies

Sweet Corn IPM Newsletter No. 6 – July 19, 2012

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

WARM NIGHTS LEAD TO CORN GROWTH, PEST ACTIVITY STILL LOW

Spotted Wing Drosophila Alert

SITUATION
Despite the warmer night temperatures over the weekend, moth counts remain low.  In many places, the warm nights helped the corn grow rapidly, while in other places corn is exhibiting symptoms of dehydration because of the lack of rain.

European corn borer:  Moth counts continue to be very low this week.  Two sites, Levant and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn exceeded the 15% feeding injury threshold in Biddeford, one Cape Elizabeth location, Jefferson, one Lewiston location, Oxford, Poland Spring, Sabattus and one Wells location this week.

 

Corn earworm:  No sprays were recommended for corn earworm this week.  Most locations had no moths, and the locations where corn earworm was present only saw a single moth, which doesn’t warrant a spray.

Fall armyworm:  Though we were expecting moth counts to increase after the warmer nights over the weekend, no fall armyworm moths were caught this week and we have not yet seen any sign of larvae feeding.

Spotted Wing Drosophila (SWD) Alert:  This 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 fly around the over-ripe bananas in your kitchen.  However, this species will lay its eggs in 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.  Now that spotted wing drosophila has been confirmed in Limington, Mechanic Falls, Springvale, Thorndike, and Warren, 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.  There is also a good fact sheet on management of spotted wing drosophila on the Penn State Extension website.

Sincerely,

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%ECB Damage Recommendations / Comments
 Biddeford  1  0  0  24% One spray recommended for ECB feeding
 Cape Elizabeth I  0  1  0  1% No spray recommended
 Cape Elizabeth II  0  0  0  29% One spray recommended for ECB feeding
 Charleston  0  1  0  0% No spray recommended
 Dayton I  1  0  0  0% No spray recommended
 Dayton II  1  1  0  0% No spray recommended
 Dresden  0  0  0  3% No spray recommended
 East Corinth  0  6  0  2% One spray recommended for ECB on silking corn
 Farmington  1  0  0  6% No spray recommended
 Jefferson  1  1  0  25% One spray recommended for ECB feeding
 Levant  0  5  0  5% One spray recommended for ECB on silking corn
 Lewiston  1  1  0  2% No spray recommended
 Lewiston II  0  2  0  13% No spray recommended
 Livermore Falls  0  0  0  2% No spray recommended
 Monmouth  0  0  0  0% No spray recommended
 New Gloucester  0  0  0  1% No spray recommended
 Nobleboro  0  4  0  4% No spray recommended
 North Berwick  0  0  0  4% No spray recommended
 Oxford  0  0  0  27% One spray recommended for ECB feeding
 Palmyra  0  3  0  1% No spray recommended
 Poland Spring  1  0  0  41% One spray recommended for ECB feeding
 Sabattus  0  0  0  19% One spray recommended for ECB feeding
 Wales  0  0  0  0% No spray recommended
 Warren  0  0  0  7% No spray recommended
 Wells I  1  1  0  18% One spray recommended for ECB feeding
 Wells II  0  0  0  2% No spray recommended

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB:  European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

 Moths caught per week  Moths caught per night  Spray interval
 0.0 to 1.4  0.0 to 0.2  No spray
 1.5 to 3.5  0.3 to 0.5  Spray every 6 days
 3.6 to 7.0  0.6 to 1.0  Spray every 5 days
 7.1 to 91  1.1 to 13.0  Spray every 4 days
 More than 91  More than 13  Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Image Description: Sweet Corn

Image Description: European Corn Borer on Ear

Image Description: Male and Female Spotted Wing Drosophila Flies

Strawberry IPM Newsletter No. 6 – July 5, 2012

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

RENOVATION AND WEED MANAGEMENT ISSUE

Spotted Wing Drosophila, White Grubs Threaten Berries this Summer

The open winter of 2011-2012 with its lack of snow cover raised fears of winter injury in strawberry beds this spring.  The early warm up also led to a very early bloom and an increased risk of frost injury.  For most growers, however, relatively mild winter temperatures and good mulch cover prevented widespread winter injury, and well-timed irrigation prevented significant frost damage.  It seemed everything was in place for a very early season, when it started to rain, and rain and rain.  This slowed strawberry development considerably and raised concern about preventing fruit rots, such as gray mold (Botrytis) and leather rot (Phytophthora).  Fungicide sprays through the wet period provided good protection in most fields, as gray mold was kept to a minimum in spite of all the moisture.  The harvest season was pushed back to just a few days ahead of normal for most fields, but the crop was not as heavy as the bloom led us to believe, and the season ended up being fairly short.  As fruit ripened we saw some plants showing signs of stress and, depending upon which field we were in, the problems were related to Phytophthora crown rot, winter injury, black root rot, and/or white grubs.

Don’t forget about your strawberries after harvest.  Follow the recommended renovation steps listed below as soon after harvest as possible, and continue to scout for and manage disease, insect and weed problems as they arise.  Some of the more common issues to be alert for during the summer are listed below.

DISEASES:  Foliar diseases should be monitored in your fields by regularly examining leaves.  All of the common leaf diseases were present in fields this spring and we should expect that they will continue to be a problem through the summer.  The most common summer diseases are powdery mildew, leaf spot and leaf scorch.  Fungicides available for these diseases include captan, Topsin-M®, Cabrio®, Pristine® and Abound®.  See the New England Small Fruit Pest Management Guide for detailed descriptions of these diseases and their management.

Black root rot is a disease complex which can be brought on by a combination of problems, including nematodes, soil fungi (Rhizoctonia, Pythium), herbicide carryover, and soil compaction.  Plants become weak and may wilt and die.  Roots on affected plants are black and poorly developed.  This tends to be a problem in fields that have been in strawberries constantly for many seasons, and in fields that are under stress in other ways, such as winter injury.  Rotating fields to crops other than strawberries for at least three years is an important management strategy for black root rot.  Improving soil drainage and breaking up hardpans in the soil may also help.  Recent studies suggest that pre-plant root dips with azoxystrobin (Abound®) may also reduce incidence of black root rot in some fields.

INSECTS:  If black vine weevils or strawberry root weevils are a problem in a strawberry field that you would like to carry over, bifenthrin (Brigade®) can be applied when adult feeding is noticed (usually until mid-late July).  Look for notching along the leaf edges and the presence of the black or brown snout beetles.  Applications should be made at night when these insects are active, and the highest rate of the insecticide should be used.  For control of the grubs a soil drench of Platinum® (thiamethoxam) insecticide should be applied during the fall and/or early spring when the grubs are active in the soil.  This product has a 50 day pre-harvest interval and may also be used as a pre-plant or planting treatment for root weevils.  Parasitic nematodes such as Heterorhabditis bacteriophora or Steinernema feltiae can also be applied to provide control of root weevil grubs in late August.  Nematodes require specialized handling and application.  Contact us or talk with one of the suppliers for more details.  See the New England Small Fruit Pest Management Guide for sources.

White grubs have been a problem in many fields this spring/summer.  The grubs may be the larvae of several species of scarab beetles, including June beetles, rose chafers, Japanese beetles, Asiatic garden beetles and European chafers.  The beetles lay their eggs in June and July and the grubs feed on the roots of strawberries from July through mid September.  Affected plants will be stunted and wilted and may die during dry periods.  Pulling up plants reveals that roots have been chewed off about an inch below the soil line.  Sifting through the soil below the plants may reveal the whitish crescent-shaped grubs which can range in size from 3/8 inch to almost 1 ½ inches long, with six legs near the head and a swollen rear-end.  The two most effective periods to treat plantings for grubs are in the spring prior to when they pupate (May) and in the late summer when the next generation is actively feeding (late August).  Materials should be applied with plenty of water to moist soil to be sure they reach the root zone.  Materials currently registered for control of grubs include Platinum® and Admire®.  Parasitic nematodes can also provide control of grubs and should be applied with similar timing.  Nematodes are very sensitive to ultraviolet light and dehydration and must be applied with lots of water.  See the New England Small Fruit Pest Management Guide for sources of parasitic nematodes.

Strawberry rootworm (not root weevil) is a small (1/8″) dark brown to black beetle which feeds on strawberry foliage, causing it to look skeletonized.  The small larvae feed on strawberry roots, further weakening the plant.  Adult feeding damage on the leaves usually occurs in late July through August.  Heavy rootworm feeding weakens strawberry plants so control is warranted when injury is noticed.

Keep a lookout for potato leafhoppers, which can weaken strawberry plants and spread disease.  The potato leafhopper does not overwinter inMaine, but must fly in from southern states.  These small, bullet-shaped insects feed on plant sap from the undersides of leaves, causing the leaves to become curled, stunted and yellow-streaked.  Symptoms are often first noticed in new strawberry plantings, but leafhoppers will also infest older plantings and a variety of vegetables, flowers and fruit crops.  To scout for leafhoppers, brush the leaves of the plants with your hand.  The small, whitish adults can be seen flying off the plant.  Examine the underside of some injured leaves.  Look for small, light green leafhopper nymphs.  They are about 1/16 inch long.  When touched, they will crawl sideways in a crab-like manner.  Controls for potato leafhoppers include malathion, carbaryl or Provado®.

MITES:  Two-spotted spider mites can become problems during the summer.  Continue to take leaf samples for spider mites after renovation.  If more than 25% of a 60-leaf sample has mites, controls should be applied.  Summer is an ideal time to use predatory mites to control pest mites, because they prefer warm temperatures, and there is less chance of an insecticide spray that might kill them.  Amblyseius fallacis can provide good control of two-spotted spider mites when they are released at a rate of about 10,000 mites per acre.  Predator mite releases should only be made after a spider mite infestation has been found in the field.  Releasing predators into a clean field will often result in them dying, due to a lack of food.  See the New England Small Fruit Pest Management Guide for sources of predatory mites.

Cyclamen mites:  Plants showing weak growth and yellow, crinkled leaves may be infested with cyclamen mite.  Cyclamen mites are very small and reside down in the crown of the strawberry plant feeding on the developing leaves.  They are very hard to see, even with magnification.  Miticides such as Thionex®, Kelthane® or Portal® can be effective, but must be applied with lots of water to be sure that the material is carried down into the crowns.  If you suspect you have this problem, give us a call.

WEEDS:  Weeds can become a big problem during the summer because they are often forgotten among all the other demands on our time and because of limited control options.  However, the importance of good weed management should not be underestimated.  Keeping weeds under control this summer will prevent future infestations.  Here’s a summary of weed control options for strawberries:

1.  Cultivation:  Following renovation, cultivation between strawberry rows can provide effective temporary control of annual weeds.  Several types of cultivators are available which will work well in strawberry beds.  Cultivators can also be used to help sweep runners into the plant rows.

2.  DCPA (Dacthal®):  A pre-emergent herbicide used in the early spring, late fall or after renovation.  It offers good, short-term control of some annual broadleaf weeds and grasses.  It is weak on ragweed, galinsoga, smartweed, shepherd’s purse and mustard.  Its action will be improved if worked into the soil by irrigation or light cultivation, and it tends to work best in lighter, warmer soils.  This may be used as an alternative to terbacil or napropamide when there is a high risk of plant injury from those products.

3.  Napropamide (Devrinol®):  A pre-emergent herbicide which provides good control of annual grasses, volunteer grains and some broadleaf weeds.  It is typically applied just before mulching in the fall.  Split applications have become popular due to the loss of other pre-emergent herbicides, e.g. half maximum rate application after renovation or in late summer after desired daughter plants have rooted, and a second half rate application once the strawberry plants are dormant.  Napropamide should be activated by irrigation, rainfall or light cultivation within 24 hours of application.  Repeated long-term use of this material, i.e. with no crop rotation, may eventually result in poor daughter plant establishment, due to rooting inhibition.

4.  Terbacil (Sinbar®):  An effective pre-emergent herbicide with some post-emergent activity, which should be applied at renovation time – after mowing and tilling the beds, but before new growth begins.  A second application can be made in late fall, after the plants are dormant.  No more than 6 oz. may be applied in a single application, and no more than 8 oz. may be applied in one season.  An example of one season’s use could be 5 oz. applied at renovation and 3 oz. applied in the late fall, the latter in addition to napropamide or DCPA.  Terbacil can cause injury to strawberry plants.  It is important to determine appropriate rates for each location.

5.  Sethoxydim (Poast®):  A post-emergent herbicide for control of actively growing grasses. It will not control broadleaf weeds.  It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days.  Do not use sethoxydim within six weeks of a terbacil (Sinbar®) application to avoid leaf injury.  Sethoxydim should be used in combination with a crop oil concentrate.  Do not tank mix with 2, 4-D.

6.  Clethodim (Arrow®, Prism®, Select®):  A post-emergent herbicide, similar in activity to Poast®, for control of actively growing grasses. It will not control broadleaf weeds.  It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days.  Clethodim should be used in combination with a crop oil concentrate.

7.  Paraquat (Gramoxone Inteon®):  A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds.  Paraquat will injure or kill strawberries, so applications are made between rows only, with a sprayer shielded to protect the strawberries.  It should be used in combination with a nonionic surfactant.  Paraquat should not be applied within 21 days of harvest or more than three times in one season.

8.  Pelargonic Acid (Scythe®):  A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds.  Scythe® will injure or kill strawberries, so applications are made between rows only, with a sprayer shielded to protect the strawberries.  This product has a relatively low toxicity and no residual soil activity.  It has a strong, unpleasant odor.

9.  2,4-D Amine (Formula 40®, Amine 4):  A post-emergent herbicide effective on most broadleaf perennial weeds.  It will not control grasses, nor offer any pre-emergent control.  2,4-D should be applied immediately after harvest is complete if emerged broadleaf weeds are a problem.  After application, the bed should be left undisturbed for three to five days, before mowing the leaves off the plants.  This allows time for the material to be taken in by the weeds.  This material can also be used when the plants are dormant (late fall or early spring) to control winter annuals and biennials.  Such applications have been of minimal benefit in northern New England, and sometimes result in injury to the strawberries.  Do not tank mix 2,4-D with sethoxydim (Poast®).

10.  Flumloxazin (Chateau®):  A pre-emergent herbicide for control of broadleaf weeds, including dandelion and shepherd’s purse.  For use in the fall when plants are dormant for control of weeds the following spring.

11.  Pendimethalin (Prowl H20®):  A pre-emergent herbicide that may be applied as a band with a shielded sprayer between the rows of strawberries.  No weed control will be provided within the plant rows, and contact of this product on the strawberry plants will cause injury.  May not be applied within 35 days of harvest.

The use of herbicides alone rarely gives complete weed control. Some hand weeding will be necessary.  To provide good weed control throughout the life of a strawberry bed, growers should concentrate on crop rotation and good pre-plant weed control.

Strawberry Bed Renovation Review

Bed renovation should begin as soon after harvest as possible.  The earlier the beds get renovated, the more time runner plants have to develop, which means larger crowns and more flower buds for next year.  Early renovation also improves weed management by tilling in many weeds before they go to seed, and can help with insect and foliar disease control by interfering with life cycles at a critical stage of development.  The first step in the bed renovation process is to determine which beds should be carried over for another year and which should be plowed down and put into a crop rotation.  Beds that did not suffer much from winter injury had good production and a good plant stand with no major weed, insect or disease problems should be carried over for another year.  Beds that do not meet these criteria should be plowed down and seeded to a suitable cover crop to reduce weed, insect and disease problems that have developed, and to increase soil organic matter content.  Ideally, beds that are plowed down should be rotated out of strawberries for at least three years.  If properly managed, crop rotation will greatly reduce pest problems and improve the vigor and longevity of strawberry beds without the need for soil fumigation.

Renovating a strawberry bed is basically a thinning process to promote healthy new growth that can support a good crop next spring.  While some parts of the following renovation scheme may need to be modified for individual situations, all beds should undergo the following steps once harvest is complete.

1.  Broadleaf weed control:  If perennial broadleaf weeds such as dandelion, shepherd’s purse, daisy or goldenrod are a problem and/or a high population of annual broadleaf weeds such as lambsquarters, sorrel or pigweed are present, hand-pull as many as possible, especially within the plant rows, and/or apply 2,4-D amine (Formula 40®).

2.  Leaf mowing:  Four to five days following the 2,4-D application (or immediately if 2,4-D was not applied) mow off the leaves of the strawberries about 1 ½ inches above the crowns.  If the planting is weak, it is recommended that this step of the renovation process be skipped.

3.  Fertilization:  Apply 40 to 60 pounds of actual nitrogen per acre (use the higher rate on sandy soils and fields where growth has been weak).  Phosphorus and potassium applications should be made according to soil test recommendations.  Soil testing kits and information are available from your county Cooperative Extension office.

4.  Plant thinning:  For the single matted row system, strawberry plant rows should not be any wider than 24 inches.  After mowing off the leaves, till the sides of the rows to narrow the beds back to a width of 12 to 18 inches.  Use the wider setting for varieties that tend to throw few runners or any fields experiencing drought stress.   Set the tiller so that it incorporates the mowed leaves and spreads about one inch of soil over the remaining crowns at the same time.  This will reduce leaf disease and mite problems, and help stimulate new root growth on the remaining plants.

5.  Pre-emergent weed control:  To control annual weeds, apply terbacil (Sinbar® 80WP) according to label directions (2 to 6 oz. per acre).  Be sure to follow all label precautions.  To avoid plant injury, do not use terbacil if you do not intend to mow off the leaves.   Napropamide (Devrinol®) or DCPA (Dacthal®) may be used as an alternative to terbacil at this time, as described below.  If you are not using herbicides, regular cultivation, before weeds are more than 2” tall, will be needed throughout the summer.

6.  Subsoiling:  Soil compaction caused by tractor and picker traffic in the field can cause soil drainage problems and interfere with good root development.  Using a subsoiling blade between the rows will break up compacted layers of soil and improve water infiltration.  Subsoiling is best done late in the renovation sequence to prevent interference from straw and crop residues.

7.  Irrigation:  To encourage rapid plant growth and get the most out of fertilizers and herbicides, irrigate the beds regularly.  Strawberries will grow best if they receive 1 ½ inches of water per week during the growing season.

Don’t forget your plants once these renovation steps are completed.  Check the strawberry fields regularly during the summer for pest problems.  Finding and managing problems early can prevent major problems next spring.  Pay close attention to the following items:

NUTRITION:  Following the application of 40 to 60 pounds of actual nitrogen at renovation, another 20 pounds of nitrogen should be applied in mid- to late-August to stimulate flower bud development.  One way to determine the nutrient status of strawberry plants during the summer is to have a leaf tissue analysis done.  Tissue analysis offers a view of what is happening within the plant, and can spot any nutrient deficiencies.  In combination with regular soil tests, tissue analysis will provide a complete picture of a field’s fertilizer needs.  For more information about tissue analysis contact:  Analytical Lab, 5722 Deering Hall, Rm. 407, University of Maine, Orono, ME 04469-5722, telephone: 581.2945.

 

Pest Management for Day-Neutral Strawberries

Most of the important pests that damage June-bearing varieties can be as much or more of a problem on day-neutral types.  Because day-neutral strawberries will have buds, flowers and fruit all occurring at the same time, it is critical to pay close attention to the required number of days to harvest after a pesticide application, to be sure you can safely harvest ripe fruit while still protecting buds and blossoms.  Some of the more important pests are listed below, along with currently recommended pesticides and days to harvest as stated on current labels.

Spotted wing drosophila (Drosophila suzukii) is a new pest which is likely to be a concern for day neutral strawberries, fall raspberries and blueberries.  This is a small fruit fly, similar to the type that fly 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 late in the 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.  To date (7/5/12) spotted wing drosophila has been confirmed in berry plantings in Connecticutand Massachusetts, so we expect to find it here soon.  Products that provide good control of drosophila on strawberries include Delegate®, Brigade®, Danitol®, and malathion.  Keeping 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.

Tarnished plant bug:  This is one of the most prevalent and persistent pests of day-neutral strawberries, as summer flowering coincides with peak populations of this insect.  Adult and nymph stages feed on the flowers and developing fruit, causing them to have seedy ends and other malformations.  Regular insecticide applications are often required to keep the damage in check.  Scout the flower clusters for adults and nymphs often to determine if controls are necessary.  Insecticide products for tarnished plant bug include:

Tarnished Plant Bug
Product Days to Harvest
Brigade® 0
Pyganic® 0
Assail® 1
Dibrom® 1
Rimon® 1
malathion 3
Thionex® 4

 

Two-spotted spider mites:  Mites can become a problem during the summer when the growing conditions are warm and dry.  In addition to infesting the leaves, mites can move onto the fruit, reducing marketability.  Plants that are drought-stressed, over fertilized with nitrogen, or prone to dust covering, e.g. growing beside a dirt road, are especially prone to mite infestation.  Predatory mites can be an effective means to control spider mites and keep them in check over the season.  Releases should only be made when spider mites are present in the field to provide the predators with a source of food.  Most of the products labeled for controlling spider mites will also kill predatory mites, so do not use these products after predators have been released.  Scout for mites often during the season by examining the undersides of the leaves.  Control is warranted if more the 25% of leaves examined have mites.
Two-Spotted Spider Mites
Product Days to Harvest
Brigade® 0
Zeal® 1
Vendex® 1
Acramite® 1
Danitol® 2
Agri-Mek® 2
Oberon® 3
Savey® 3
Kelthane® 3

Potato leafhoppers, sap beetles, thrips and spittlebugs may also become problems on day-neutral strawberries, but are less frequently observed than tarnished plant bug and spider mites.  Recommendations for these insects can be found in the current edition of the New England Small Fruit Pest Management Guide.

Foliar and fruit diseases also need to be managed on day-neutral strawberries, and should be controlled in much the same way as they are for June-bearing varieties.  Most of the fungicide products labeled to control gray mold, powdery mildew, leaf spot and leaf scorch have either zero or one day to harvest, so protecting blossoms at the same time as fruit is near harvest should not be a problem; but be sure to check labels carefully and schedule your sprays and harvests accordingly.  Anthracnose fruit rotcan be especially troublesome for day-neutral strawberries, because it grows well under warm conditions and spreads by splashing water, which is encouraged on plastic mulch.  Fungicides registered for control of anthracnose include Cabrio®, Abound®, Pristine® and Switch®, all of which have zero days to harvest restriction.

Visit the 2010-2011 New England Small Fruit Pest Management Guide online for more detailed pest information.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                                  PestManagement
P.O. Box179                                      491 College Avenue
Monmouth,ME 04259                        Orono,ME 04473
207.933.2100                                   1.800.287.0279

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

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant Universityof the state of Maine and the U.S. Department of Agriculture Cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.
A Member of the University of Maine System

Image Description: Strawberries

Image Description: Leaf Spot on Strawberry Plant

Image Description: Black Vine Weevil

Image Description: White Grub

Image Description: Strawberry Rootworm Beetle

Image Description: Potato Leafhopper

Image Description: hopperburn1

Image Description: Two-spotted Spider Mites

Image Description: Cyclamen Mite Damage

Image Description: Mowing Strawberry Leaves

Image Description: Strawberry Irrigation

Image Description: Sidedressed Strawberry Planting

Image Description: Male Spotted Wing Drosophila

Image Description: Large Tarnished Plant Bug Nymph

Image Description: Tarnished Plant Bug Injury on Strawberries

Image Description: Two-spotted Spider Mites

Image Description: Anthracnose on Strawberry


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University of Maine Cooperative Extension


Contact Information

Cooperative Extension at Highmoor Farm
52 U.S. Route 202
Monmouth, Maine 04259-0179
Phone: 207.933.2100
The University of Maine
Orono, Maine 04469
207.581.1110
A Member of the University of Maine System