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CORN EARWORM COUNTS CLIMBING
Pest Pressure Now Moderate for Most Locations
Despite a series of storms coming up from the south, corn pest pressure has remained moderate in most locations this week. Harvest of early corn planted under plastic will likely start next week in southern Maine.
European corn borer: Moth counts were erratic again this week, with some locations having the highest numbers of the season, while others had none. Silking fields in Dayton, Lewiston, Livermore Falls, Nobleboro and Sabattus were over the threshold of 5 moths per week in silking corn. The Lewiston, Nobleboro and Sabattus sites were also on a spray regime for corn earworm, so no additional spray was recommended. European corn borer feeding damage was over threshold in pre-tassel to tasseling fields in Biddeford, Nobleboro, North Berwick and Sabattus this week.
Corn earworm: Most locations have now caught at least one corn earworm moth, and counts have risen in a few locations this week. But moth numbers are still relatively low in many fields, given the recent storms moving in from the south. A 6-day spray interval was recommended for corn earworm on silking fields in one Cape Elizabeth location, one Dayton location, Gray, New Gloucester, Nobleboro, North Berwick, Sabattus and one Wells location. A 5-day spray interval was recommended for one Cape Elizabeth site and one Lewiston site. A 4-day spray interval for silking corn was recommended for Wales and Warren.
Fall armyworm: Moth counts were mostly very low this week. Only one site in Cape Elizabeth exceeded the threshold of 3 moths per week in silking corn. However, this field was also on a spray regime for corn earworm, so no additional sprays should be needed. Feeding damage on plants was noted this week in fields in Biddeford, North Berwick and one Wells site. Although not yet over threshold on it’s own, when combined with European corn borer damage the total feeding exceeded the 15% threshold.
Japanese Beetles are becoming plentiful in southern and mid-state areas. These insects often find their way into cornfields and may feed on the silks of developing ears, causing poor tip fill. Sprays for corn earworm (except Bt’s) will often control the Japanese beetle as well.
Squash vine borer moths were caught in pheromone traps in Biddeford, Cape Elizabeth, Dayton, New Gloucester and Wells this week. This week’s counts were some of the highest we’ve seen. The threshold of five moths per week was exceeded in Dayton, New Gloucester and Biddeford. Vine borers threaten summer squash, winter squash and pumpkins. See the New England Vegetable Management Guide for control options.
Late Blight Update: Infections have been confirmed from potatoes in commercial fields and home gardens in southern Maine. With hot, humid weather, this disease can spread rapidly through a region. Growers should scout their potato and tomato fields for symptoms and apply preventative fungicides. For more information visit our Cooperative Extension Publications website and the 2014-2015 New England Vegetable Management Guide.
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
Sweet Corn IPM Weekly Scouting Summary
|Recommendations / Comments|
|Biddeford||0||1||1||18%||One spray recommended for ECB + FAW feeding|
|Cape Elizabeth I||2||3||0||5%||6-day spray interval recommended on all silking corn|
|Cape Elizabeth II||4||0||10||5-day spray interval recommended on all silking corn|
|Charleston||0||0||1||No spray recommended|
|Dayton I||0||7||0||One spray recommended for ECB on silking corn|
|Dayton II||2||0||1||11%||6-day spray interval recommended on all silking corn|
|Farmington||1||2||1||2%||No spray recommended|
|Garland||1||0||0||0%||No spray recommended|
|Gray||2||1||0||6-day spray interval recommended on all silking corn|
|Levant||0||2||0||0%||No spray recommended|
|Lewiston I||6||5||0||5-day spray interval recommended on all silking corn|
|Lewiston II||1||3||0||0%||No spray recommended|
|Livermore Falls||1||12||0||2%||One spray recommended for ECB on silking corn|
|Monmouth||1||0||0||No spray recommended|
|New Gloucester||2||0||1||1%||6-day spray interval recommended on all silking corn|
|Nobleboro||3||5||0||29%||6-day spray interval recommended on all silking corn|
|No. Berwick||2||0||0||41%||6-day spray interval recommended on all silking corn|
|Oxford||0||4||0||1%||No spray recommended|
|Palmyra||0||2||0||0%||No spray recommended|
|Sabattus||3||8||0||23%||6-day spray interval recommended on all silking corn|
|Wales||8||1||0||0%||4-day spray interval recommended on all silking corn|
|Warren||9||0||1||4-day spray interval recommended on all silking corn|
|Wells I||0||2||0||8%||No spray recommended|
|Wells II||2||2||1||2%||6-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
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.