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Corn Earworm Has Arrived. Protect Silking Corn!
Fall Armyworm a Threat to Younger Corn
SITUATION
Early corn harvest continues in Southern Maine. Warm weather has kept later corn growing at a rapid pace, especially in irrigated fields. Both corn earworm and fall armyworm have made stronger appearances this week, emphasizing the need to protect silking corn where these pests have been found. Corn earworm populations are at their highest of the season and fall armyworm feeding injury is becoming more widespread.
Green Silk Stage, photo by David Handley
European corn borer: Moth counts are generally low again this week. Only one spray was recommended for exceeding threshold for silking corn in Farmington. Dresden was also over threshold, but already on a spray interval for corn earworm. Larval feeding injury exceeded threshold in non-silking corn only when combined with fall armyworm feeding injury in one site in Wells this week.
European Corn Borer Larvae on Ear, photo by David Handley
Corn earworm: Pheromone trap catches continue to be low in most locations this week. Four-day spray intervals were recommended in Biddeford, one site in Cape Elizabeth, Charleston, one site in Dayton, Dresden, Levant, Nobleboro, North Berwick, and Old Town. Five-day spray intervals were recommended in Jefferson, one Lewiston site, Monmouth, New Gloucester, Sabattus, and one Wells site. Six-day spray intervals were recommended for silking corn fields in Corinth, one Dayton site, Livermore, Palmyra, and Warren. Single moths were caught in Farmington, one Lewiston site, Oxford, Poland Spring, Readfield, and Wales; but these were not significant enough to warrant a spray.
Corn Earworm Larvae, photo by David Handley
Fall armyworm: Moths exceeded threshold for silking corn in two locations this week, New Gloucester and Poland Spring. The New Gloucester field was already on a spray interval for corn earworm, so no additional sprays should be needed. A single spray to protect silking corn was recommended at the Poland Spring site. Fall armyworm feeding injury exceeded the 15% threshold for pre-tassel stage corn in Biddeford, both sites in Cape Elizabeth, Dresden, North Berwick, Poland Spring, and combined with ECB at one site in Wells. Single protective sprays were recommended on non-silking corn in all of these locations.
Fall Armyworm Injury on Corn Leaves, photo by David Handley
Late Blight: Grower and Farm Stand Alert
Potato late blight, the disease that caused the significant crop losses for tomatoes and potatoes in Maine last year has just been confirmed at a sight in Waldoboro, and several other suspected sites are now being investigated. An announcement is enclosed with more information. Please feel free to contact the University of Maine Cooperative Extension Pest Management Office with any questions.
Late Blight Hotline:
For the most recent information, call the IPM Hotline at 207.760.9IPM (207.760.9476). PMO@umext.maine.edu
Sincerely,
David T. Handley
Vegetable & Small Fruit Specialist
Highmoor Farm Pest Management Office
P.O. Box 179 491 College Ave
Monmouth, ME 04259 Orono, ME 04473
207.933.2100 1.800.287.0279
| Location | CEWMoths | ECBMoths | FAWMoths | %ECB Damage | Recommendations / Comments |
| Biddeford | 18 | 0 | 2 | 38% | 4-day spray interval recommended for all silking corn |
| Cape Elizabeth I | 0 | 0 | 2 | 49% | One spray recommended for FAW feeding injury |
| Cape Elizabeth II | 16 | 0 | 0 | 26% | 4-day spray interval recommended for all silking corn |
| Charleston | 9 | 1 | 0 | 4% | 4-day spray interval recommended for all silking corn |
| Corinth | 2 | 3 | 0 | 0% | 6-day spray interval recommended for all silking corn |
| Dayton I | 3 | 1 | 1 | 11% | 6-day spray interval recommended for all silking corn |
| Dayton II | 24 | 0 | 1 | 7% | 4-day spray interval recommended for all silking corn |
| Dresden | 18 | 6 | 1 | 15% | 4-day spray interval recommended for all silking corn |
| Farmington | 1 | 6 | 0 | 2% | One spray recommended for ECB on all silking corn |
| Jefferson | 4 | 0 | 0 | 8% | 5-day spray interval recommended for all silking corn |
| Levant | 10 | 4 | 0 | 2% | 4-day spray interval recommended for all silking corn |
| Lewiston I | 7 | 0 | 1 | 0% | 5-day spray interval recommended for all silking corn |
| Lewiston II | 1 | 2 | 0 | 0% | No spray recommended |
| Livermore | 3 | 0 | 0 | 8% | 6-day spray interval recommended for all silking corn |
| Monmouth | 7 | 1 | 0 | 1% | 5-day spray interval recommended for all silking corn |
| New Gloucester | 4 | 0 | 5 | 0% | 5-day spray interval recommended for all silking corn |
| Nobleboro | 10 | 3 | 1 | 7% | 4-day spray interval recommended for all silking corn |
| North Berwick | 15 | 2 | 0 | 35% | 4-day spray interval recommended for all silking corn |
| Old Town | 11 | 1 | 0 | 0% | 4-day spray interval recommended for all silking corn |
| Oxford | 1 | 1 | 0 | 0% | No spray recommended |
| Palmyra | 3 | 1 | 0 | 2% | 6-day spray interval recommended for all silking corn |
| Poland Spring | 1 | 1 | 3 | 16% | One spray recommended for FAW on all silking corn |
| Readfield | 1 | 1 | 0 | 3% | No spray recommended |
| Sabattus | 5 | 3 | 1 | 0% | 5-day spray interval recommended for all silking corn |
| Wales | 1 | 0 | 1 | 0% | No spray recommended |
| Warren | 3 | 2 | 1 | 8% | 6-day spray interval recommended for all silking corn |
| Wells I | 4 | 0 | 0 | 0% | 5-day spray interval recommended for all silking corn |
| Wells II | 0 | 0 | 1 | 13% | One spray recommended for FAW + ECB feeding injury |
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. |
| 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. |
| 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. |
Late Blight: Grower and Farm Stand Alert
Potato late blight, the disease that caused the significant crop losses for tomatoes and potatoes in Maine last year has just been confirmed at a sight in Waldoboro, and several other suspected sites are now being investigated. Typical symptoms will be a water-soaked grease spot on foliage with a fine white mycelium on the underside of the leaflet. A stalk infection will usually look dark brown, almost black.
Late Blight: Water-Soaked Spots on Potato Leaf, photo by Jim Dill
Late Blight on Tomato Leaves, photo by Jim Dill
The spores released by infected plants have the ability to travel 40 plus miles under the right conditions and infect potato and tomato plants. We are encouraging all commercial growers and home gardeners to be carefully inspecting their plants for disease. If late blight is found we are asking that the diseased plants be destroyed. They can be buried or simply bagged so that the spores can not escape and that the plant will die. Late blight is an obligate parasite and needs living tissue in order to survive. Applications of protective fungicides should be applied to tomato and potato crops if they have not been receiving regular applications up to this point.
The Pest Management Office in Orono will look at any samples that you may suspect have been infected. When sending samples, they should be placed in a plastic bag with a piece of dry paper towel to keep the sample fresh. For pictures of this disease visit the following websites:
www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm
www.longislandhort.cornell.edu/vegpath/photos/lateblight_potato.htm
The Pest Management Office has copies of a home gardener alert, a late blight ID sheet for roadside stand producers and a poster for late blight identification that you can use to make your help and your customers more aware of this potentially devastating disease.
Please feel free to contact The University of Maine Cooperative Extension Pest Management Office with any questions.
Late Blight Hotline:
For the most recent information, call the IPM Hotline at 207.760.9IPM (207.760.9476).
Pest Management Office
491 College Avenue
Orono, ME 04473
1.800.287.0279
PMO@umext.maine.edu
David T. Handley, Ph.D.
Vegetable & Small Fruit Specialist
University of Maine Cooperative Extension
Highmoor Farm
P.O. Box 179
Monmouth, ME 04259-0179
207.933.2100
Fax 207.933.4647
7-20-2010