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Sweet Corn IPM Newsletter No. 9 – August 23, 2013

Sweet Corn IPM Newsletter No. 9 – August 23, 2013

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

CORN PEST PRESSURE INCREASING IN SOUTHERN AND COASTAL REGIONS

Higher Moth Counts Require Tighter Spray Schedule for Silking Corn

SITUATION
A stretch of nice weather has been good for corn growth, but also appears to have allowed corn pests to build up in southern and coastal sites. Pest pressure is fairly light for this late in the season, however, as the tropical storm activity that often brings corn pests into the state late in the summer has been very quiet.

European corn borer:  Moth catches were very low again this week, with the exception of a couple of northern sites. Fields in Nobleboro and Levant exceeded the threshold of 5 moths per week in silking corn, but the Nobleboro field is under a spray interval for corn earworm, so no additional sprays should be required. No fields had European corn borer feeding damage over threshold.

Corn earworm:  Moth counts are rising in some southern and coastal locations, although many locations still had no moths in pheromone traps this week and do not require a spray interval for silking corn at this time.  A 4-day spray interval was recommended for silking corn in Biddeford and one Cape Elizabeth site.  A 5-day spray interval was recommended for fields in Auburn, Dayton and Nobleboro, Warren and one Wells site. A 6-day spray interval was recommended for silking fields in Lewiston, Monmouth and New Gloucester.

Fall armyworm:  Moth counts have increased in some southern and coastal sites, but many sites caught no moths this week. Fall armyworm moths were caught in Biddeford, Cape Elizabeth, Dayton, Livermore Falls, Monmouth, North Berwick, Oxford, Warren and one Wells site. The Biddeford, Cape Elizabeth, Monmouth, North Berwick, Oxford and Warren sites exceeded the weekly threshold of three moths for silking corn. Fall armyworm feeding damage on younger corn exceeded the spray threshold of 15% only at the Biddeford site.

Spotted Wing Drosophila Alert:  Fruit fly counts remain quite variable around the state. We found high numbers (100+) of flies at two sites, Limington and New Gloucester, and this may be related to lower availability of fruit at these sites, as summer raspberries are now pretty much gone. Most other sites had fewer than 4 flies for the week and many sites had none. At this point however, we recommend that all ripening fruit be protected with a recommended insecticide. Regular and repeated treatments are needed to keep fruit from becoming infested. Visit our Spotted Wing Drosophila blog for more details.

Free Disposal of Banned, Unusable Pesticides:  Farmers are urged to take advantage of a free opportunity to dispose of banned or unusable pesticides that they may have on their properties. This October, the Maine Board of Pesticides Control (BPC) and the Maine Department of Environmental Protection will dispose of banned pesticides or pesticides that have become caked, frozen, or otherwise rendered unusable. This free disposal program is open to homeowners, family-owned farms and greenhouses. All people need to do is register by September 27, 2013. Registration is mandatory; drop-ins are not permitted. To register and get more information on this program and pesticide disposal, go to the BPC website at:  www.thinkfirstspraylast.org, or call 207.287.2731.

Sincerely,

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
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Auburn 5 0 0 5-day spray interval recommended on all silking corn
Biddeford 8 0 15 15% 4-day spray interval recommended on all silking corn
Cape Elizabeth I 11 0 7 5% 4-day spray interval recommended on all silking corn
Cape Elizabeth II 1 0 16 7% One spray recommended for FAW on all silking corn
Dayton I 6 2 1 3% 5-day spray interval recommended on all silking corn
Farmington 0 2 0 0% No spray recommended
Garland 0 2 0 1% No spray recommended
Levant 0 6 0 4% One spray recommended for ECB on all silking corn
Lewiston 2 2 0 0% 6-day spray interval recommended on all silking corn
Livermore Falls 0 0 1 6% No spray recommended
Monmouth 2 0 8 6-day spray interval recommended on all silking corn
New Gloucester 3 1 0 2% 6-day spray interval recommended on all silking corn
Nobleboro 4 6 0 5-day spray interval recommended on all silking corn
No. Berwick 0 0 13 3% One spray recommended for ECB on all silking corn
Oxford 1 0 3 One spray recommended for FAW on all silking corn
Palmyra 0 4 0 3% No spray recommended
Poland Spring 1 1 0 5% No spray recommended
Sabattus 1 0 0 10% No spray recommended
Warren 7 1 4 5-day spray interval recommended on all silking corn
Wells I 0 0 0 7% No spray recommended
Wells II 6 0 1 0% 5-day spray interval recommended on 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.

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Image Description: Sweet Corn

Image Description: Corn Earworm Moth

Image Description: Adult Fall Armyworm

Image Description: Spotted Wing Drosophila Larvae in Raspberry


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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