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CORN EARWORM MOTHS MORE WIDESPREAD
European Corn Borer Feeding Over Threshold in Pre-Tassel Fields
Cool night temperatures through much of the state have slowed corn development a bit this week, although overall growth looks very good. More early fields in southern Maine are coming into tassel and a couple of fields started under plastic or row covers are in silk. Both European corn borer and corn earworm are now active in cornfields in much of the state. These are especially a threat to early silking fields, which growers often spray lightly, if at all; assuming these pests aren’t yet present in damaging numbers.
European corn borer: Moth catches are spotty around the state this week with a little less than half of the sites now catching moths. A field in Nobleboro was over threshold of 5 moths per week; but there was not yet any silking corn in the field, so no spray was recommended. European corn borer feeding damage was over the 15% threshold within pre-tassel fields in North Berwick and Livermore Falls. Otherwise, feeding damage has been very light.
Corn earworm: More locations captured corn earworm moths this week, although numbers are still low, and most fields do not yet have any silking corn that could be threatened by this pest. When more than one corn earworm moth is found at a site, all silking corn in the fields should be protected with a spray. Additional sprays are based on the average number of moths caught per week or per night (see table below). Only one field in Dayton had moths over threshold and early silking corn. A 6-day spray interval was recommended at that location, based on a weekly moth catch of 2.
Fall armyworm: No moths have been captured in our pheromone traps this week, and no feeding damage has been reported. This is usually the last major corn pest to arrive in Maine from southern overwintering sites.
Squash vine borer moths were caught in pheromone traps in Dayton and Wells this week. George Hamilton in New Hampshire has been reporting high numbers of moths this week. This pest threatens summer squash, winter squash and pumpkins. Unlike many moths, squash vine borer moths fly during the day. They are black and orange and resemble wasps. The moths lay eggs at the base of squash plants. The larvae bore into the base of the plants, causing vines to wilt and eventually collapse. The control threshold for squash vine borer moths is 5, which was exceeded at the site in Dayton this week. See the 2014-2015 New England Vegetable Management Guide for control options.
Spotted wing drosophila: The first captures of a spotted wing drosophila are being reported from southern New England this week. These small fruit flies can cause serious fruit losses in raspberries, blueberries and other soft fruits. The flies only attack fruit that has begun to ripen. We will be setting out traps for spotted wing drosophila in Maine berry fields over the next two weeks. We don’t expect populations to reach damaging levels for at least a few more weeks. For more information visit our web blog.
Highmoor Farm Field Day
The Highmoor Farm Field Day will be held on Wednesday, July 22, 2015. Visit the Highmoor Farm Field Day blog for more information.
David T. Handley
Vegetable and Small Fruit Specialist
Highmoor Farm Pest Management Office
P.O. Box 179 491 College Avenue
Monmouth, ME 04259 Orono, ME 04473
Sweet Corn IPM Weekly Scouting Summary
|Recommendations / Comments|
|Auburn||5||2||0||0%||No spray recommended (no silking corn)|
|Biddeford||0||0||0||5%||No spray recommended|
|Bowdoinham||0||3||0||No spray recommended|
|Cape Elizabeth I||0||0||0||0%||No spray recommended|
|Cape Elizabeth II||1||0||0||1%||No spray recommended (no silking corn)|
|Dayton I||2||4||0||6-day spray interval recommended on all silking corn|
|Dayton II||0||3||0||0%||No spray recommended|
|Lewiston||1||0||0||0%||No spray recommended (no silking corn)|
|Livermore Falls||0||6||0||31%||One spray recommended for ECB on pre-tassel corn|
|New Gloucester||0||0||0||No spray recommended|
|Nobleboro||2||34||0||0%||No spray recommended (no silking corn)|
|No. Berwick||1||0||0||41%||One spray recommended for ECB on pre-tassel corn|
|Poland Spring||0||0||0||1%||No spray recommended|
|Warren||0||0||0||0%||No spray recommended|
|Wells I||2||0||0||1%||No spray recommended (no silking corn)|
|Wells II||0||0||0||0%||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.
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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.