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FALL ARMYWORM MOTHS NOW IN MAINE
All Pests in Low Numbers, but Most Silking Corn Needs Protection
Some fields have been hit hard by thunderstorms during the past week while others saw only moderate temperatures and little, if any rain. The later plantings are looking better than early seeded fields with better uniformity and growth. Pests have been relatively quiet. Although we have started to catch a few fall armyworm moths in our traps, we have not yet found any larvae feeding on corn.
European corn borer: Moth counts were pretty low this week, although several sites were over the threshold of 5 moths in silking corn. We did find more feeding injury from larvae in whorl and pre-tassel stage corn, with fields scouted in Biddeford, Lewiston, Sabattus and Wells over the recommended spray thresholds.
Corn earworm: Moth counts remained low this week, and many fields do not have corn in silk, so the moths do not yet pose a significant threat to those fields. A 6-day spray interval was recommended for silking fields in Cape Elizabeth, Dayton, Dresden, and New Gloucester.
Fall armyworm: We captured our first fall armyworm moths of the season this week in two southern Maine fields. However, at these low levels, fall armyworm is not yet a threat. Fall armyworm moths tend to lay their eggs on the youngest corn available. When the larvae hatch, they chew large, ragged holes in the leaves, and may bore into developing ears. This damage is scouted for along with European corn borer injury, and a spray is recommended if the injury exceeds 15% of plants in a pre-silking field. Larvae may also move into the ears through the silk channel, behaving similarly to corn earworm. Pheromone trap catches of 3 or more moths per week indicate a spray is needed to protect silking corn, unless it is already under a spray schedule for corn earworm.
Late blight alert for potatoes and tomatoes
Late blight has recently been reported in tomato and potato plantings in coastal and central Maine. Growers should be on the alert to catch any early symptoms and be ready to apply appropriate control measures. Typical symptoms will be water-soaked lesions on the leaves with fine, white cottony mycelium on the undersides. Infections on the stems appear as dark, almost black lesions.
Please report any suspicious symptoms to the Pest Management Office 581.3883 (1.800.287.0279), or email PMO@umext.maine.edu. The latest control options for late blight on tomatoes are on the University of New Hampshire Extension web site .
David T. Handley
Vegetable & Small Fruit Specialist
Highmoor Farm Pest Management Office
P.O. Box179 491 College Ave
Monmouth,ME 04259 Orono,ME 04473
Sweet Corn IPM Weekly Scouting Summary
|ECB Moths||FAW Moths||% ECB Damage||Recommendations / Comments|
|Biddeford||0||5||0||46%||1 spray recommended for ECB feeding (no silking corn)|
|Cape Elizabeth I||0||1||1||1%||No spray recommended|
|Cape Elizabeth II||2||0||0||0%||6-day spray interval recommended for all silking corn|
|Charleston||0||0||0||0%||No spray recommended|
|Dayton I||2||1||0||7%||6-day spray interval recommended for all silking corn|
|Dayton II||3||0||1||6%||6-day spray interval recommended for all silking corn|
|Dresden||3||2||0||8%||6-day spray interval recommended for all silking corn|
|East Corinth||0||0||0||1%||No spray recommended|
|Farmington||0||0||0||3%||No spray recommended|
|Jefferson||0||0||0||0%||No spray recommended|
|Levant||0||2||0||0%||No spray recommended|
|Lewiston||4||1||0||30%||One spray recommended for ECB feeding (no silking corn)|
|Lewiston II||1||0||0||2%||No spray recommended (no silking corn)|
|LivermoreFalls||0||2||0||0%||No spray recommended|
|Monmouth||0||0||0||0%||No spray recommended|
|New Gloucester||3||0||0||0%||6-day spray interval recommended for all silking corn|
|Nobleboro||0||1||0||0%||No spray recommended|
|North Berwick||1||7||0||9%||No spray recommended|
|Oxford||0||0||0||0%||No spray recommended|
|Palmyra||0||2||0||2%||No spray recommended|
|Poland Spring||0||1||0||12%||No spray recommended|
|Sabattus||0||5||0||15%||One spray recommended for ECB feeding|
|Wales||0||0||0||0%||No spray recommended|
|Warren||0||0||0||3%||No spray recommended|
|Wells I||0||1||0||16%||One spray recommended for ECB feeding|
|Wells II||1||0||0||1%||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.
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.