Skip Navigation
Return to Layout View | Home | A-Z Directory | my UMaine | MaineStreet | Campus Map | Calendar
Follow UMaine on Twitter | Join UMaine on Facebook | Watch UMaine on YouTube | Admissions | Parents & Family | Apply | Give Now | Emergency

Cooperative Extension at Highmoor Farm


Site Navigation:


Sweet Corn IPM Newsletter No. 10 – August 15, 2012

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

HIGHEST CORN EARWORM COUNTS OF THE SEASON

Fall Armyworm Feeding Observed in Southern Maine

SITUATION
Warm weather has pushed corn maturity along rapidly and supplies are picking up.  A steady flow of weather from the south, including some heavy showers in some areas, is keeping corn earworm pressure very high in most fields this week.  Several locations are now on a recommended 3-day spray interval, which we don’t typically see until early fall when tropical storms start moving through Maine.

European corn borer:  A jump in moth counts in southern Maine suggests an emergence of a second generation of corn borer in that area.  High counts continue to be found in more northern locations as well.  These moths pose a risk to any silking corn that is not presently being sprayed for corn earworm.  Wells, Biddeford, Sabattus, 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 was low in most locations, with only Biddeford exceeding the 15% feeding injury threshold.  North Berwick exceeded the threshold when fall armyworm damage was added to the total.

Corn earworm:  Moth counts continue to increase in most locations, putting very high pressure on all silking corn.  A 3-day spray interval for fresh silking corn was recommended for Biddeford, North Berwick, and Wells this week.  A 4-day spray interval was recommended in Cape Elizabeth, Dayton, Dresden, Levant, Lewiston, Monmouth, Palmyra, Poland Spring, Sabattus, and Warren.  A 5-day spray interval was recommended for New Gloucester, East Corinth and Livermore Falls.  A 6-day spray interval was recommended for fields in Charleston and Wales.

Fall armyworm:  Moth captures remain low for this time of year, although we have started finding larval feeding damage in some southern fields.  Only one Cape Elizabeth location exceeded the spray threshold of 3 moths in silking corn, but the field is already under a spray schedule for corn earworm so no additional sprays should be needed.  Two fall armyworm moths were caught at Biddeford and our Dayton locations, and a single moth was caught in Dresden this week, below threshold for silking corn.  Fall armyworm feeding damage was found in Biddeford, Dayton, and North Berwick, but was below the 15% threshold.

Other Pests of Note:
Picnic beetles can become a problem during the late summer on silking corn.  These beetles are about ¼ inch long, black with orange spots.  They can often be found on stalks and ears that are infested with European corn borer or fall armyworm, feeding on sap at an entry or exit hole.  They will also feed on the silks and may work their way into the silk channel.  While the damage is usually insignificant, customers dislike finding the insects in their bags.  Sprays to control corn earworm should provide control of these beetles if they are found in your field.

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 %Feeding Damage Recommendations / Comments
Biddeford 97 25 2 39% 3-day spray interval for all silking corn
Cape Elizabeth I 36 2 0 0% 4-day spray interval for all silking corn
Cape Elizabeth II 70 0 3 0% 4-day spray interval for all silking corn
Charleston 3 12 0 4% 6-day spray interval for all silking corn
Dayton I 16 2 0 6% 4-day spray interval for all silking corn
Dayton II 34 1 2 10% 4-day spray interval for all silking corn
Dresden 14 0 1 5% 4-day spray interval for all silking corn
East Corinth 6 0 0 3% 5-day spray interval for all silking corn
Farmington 0 1 0 3% No spray recommended
Levant 31 11 0 13% 4-day spray interval for all silking corn
Lewiston 11 4 0 2% 4-day spray interval for all silking corn
Livermore Falls 7 0 0 6% 5-day spray interval for all silking corn
Monmouth 8 0 0 6% 4-day spray interval for all silking corn
New Gloucester 6 0 0 0% 5-day spray interval for all silking corn
North Berwick 172 4 0 17% 3-day spray interval for all silking corn
Palmyra 11 6 0 5% 4-day spray interval for all silking corn
Poland Spring 45 1 0 All Silk 4-day spray interval for all silking corn
Sabattus 8 10 0 4% 4-day spray interval for all silking corn
Wales 2 0 0 0% 6-day spray interval for all silking corn
Warren 38 1 0 10% 4-day spray interval for all silking corn
Wells I 107 1 0 All Silk 3-day spray interval for all silking corn
Wells II 92 5 0 All Silk 3-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: Print Friendly

Image Description: Sweet Corn

Image Description: European Corn Borer Entry Hole

Image Description: Corn Earworm Larvae

Image Description: Fall Armyworm on Corn Leaf


Sidebar

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