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Sweet Corn IPM Newsletter No. 5 – July 26, 2013

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Sweet Corn
Sweet Corn IPM Newsletter No. 5 – July 26, 2013
Click on photos to enlarge.


Squash Vine Borer and Spotted Wing Drosophila Pressure Increasing

Early corn harvest is coming into full swing in southern Maine. Maturity is variable, but overall quality looks good. The weather pattern has been limiting movement of moths into the region, so we have seen very little change in the populations of corn earworm and fall armyworm this week. A front moving in from the south this weekend may change the situation, but for now pest pressure remains moderate.

European Corn Borer on Ear of Corn

European Corn Borer on Ear, photo by David Handley

European corn borer: Moth catches in the southern parts of the state remain quite low this week. Two of the more northern sites had relatively high counts, however. Silking fields in Charleston and Palmyra were well over the threshold of 5 moths per week but the Charleston site is also on a spray schedule for corn earworm, so no additional sprays should be required. European corn borer feeding damage was over threshold in pre-tassel fields in Biddeford, Nobleboro and Warren this week.

Corn earworm:  Moths counts remain quite low in all locations this week and most locations did not require protection. A 4-day spray interval was recommended for Charleston and Garland. A 5-day spray interval was recommended for Levant. A 6-day spray interval was recommended for silking fields in Cape Elizabeth, Hollis and Farmington.

Fall armyworm:  Most sites had few or no fall armyworm moths in pheromone traps this week. The exceptions were Biddeford and New Gloucester, which both had 5 moths, exceeding the weekly threshold of three for silking corn. Neither site was under a spray interval for corn earworm so a spray was recommended for all silking corn. Single moths were caught in just three locations this week including Cape Elizabeth, Charleston and Oxford. Two moths were caught in Nobleboro. There is still relatively little fall armyworm feeding damage in younger corn fields.

Two Squash Vine Borer Moths

Two Squash Vine Borer Moths, photo by Jeffrey Hahn, Univ. of Minnesota

Squash vine borer moths were caught in pheromone traps in Wells, Hollis, Biddeford, Gray, New Gloucester, Nobleboro and Oxford this week. The threshold of five moths per week was exceeded in Biddeford, Hollis, Gray and New Gloucester. Be aware that this pest is very active and continues to threaten summer squash, winter squash and pumpkins. See the New England Vegetable Management Guide for control options.

Spotted Wing Drosophila Alert
Captures of spotted wing drosophila are rising this week. Flies were caught in Wells, New Gloucester, Monmouth, Dresden and Warren.  Numbers at the Warren site have increased significantly, with 84 flies caught this week. The larvae of these flies can quickly destroy any soft fruit such as raspberries and blueberries. If spotted wing drosophila has been captured in your area and you have ripening berries, the crop should be protected at this time with a recommended insecticide. Regular and repeated treatments are usually needed to keep fruit from becoming infested. Visit our Spotted Wing Drosophila blog for more details.

Highmoor Farm

FINAL REMINDER: Highmoor Farm Fruit and Vegetable Growers Field Day July 31, 2013
Join us for the Highmoor Farm Field Day and Summer Tour to be held on Wednesday, July 31, starting at 9:00 a.m. Please join us for the program, farm tours and lunch. Registration fee is $20 per person, including lunch, and preregistration is strongly encouraged. For more information, visit the Highmoor Farm website or call 207.933.2100. If you are a person with a disability and will need any accommodations to participate in this program, please call Pam St. Peter at Highmoor Farm, 207.933.2100 or TDD 1.800.287.8957 to discuss your needs at least 7 days prior to this event.


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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Recommendations / Comments
Auburn 2 7 0 0% 6-day spray interval recommended on all silking corn
Biddeford 1 0 5 35% One spray recommended on silking corn for FAW
Cape Elizabeth I 0 0 1 5% No spray recommended
Cape Elizabeth II 0 0 0 No spray recommended
Charleston 3 29 1 6% 6-day spray interval recommended on all silking corn
Dayton 0 0 0 7% No spray recommended
Farmington 2 0 0 4% 6-day spray interval recommended on all silking corn
Garland 0 5 0 1% One spray recommended on silking corn for ECB
Gray 0 5 0 7% One spray recommended on silking corn for ECB
Hollis 0 0 0 7% No spray recommended
Levant 0 5 0 3% One spray recommended on silking corn for ECB
Lewiston 2 0 0 5% 6-day spray interval recommended on all silking corn
Livermore Falls 0 0 0 13% No spray recommended
New Gloucester 0 0 5  7% One spray recommended on silking corn for FAW
Nobleboro 0 1 2 23% One spray recommended ECB feeding
No. Berwick 0 0 0 3% No spray recommended
Oxford 1 2 1 6% No spray recommended
Palmyra 0 15 0 1% One spray recommended on silking corn for ECB
Sabattus 3 2 0 5% 6-day spray interval recommended on all silking corn
Wales 3 1 0 6-day spray interval recommended on all silking corn
Warren 1 1 0 15% One spray recommended for ECB feeding
Wells I 0 0 0 5% No spray recommended
Wells II 1 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:

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.

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