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Sweet Corn IPM Newsletter No. 11 – September 6, 2018

Sweet Corn IPM Newsletter No. 11 – September 6, 2018
Click on photos to enlarge.

Last Issue for 2018!

MAJOR CORN EARWORM FLIGHT THREATENS LATE CORN

Any Late Silking Fields Remaining Require Tight Spray Interval

This will be the final issue of the Sweet Corn IPM Newsletter for the 2018 season. I would like to thank all of the growers who participated in the program this year, and our team of IPM scouts, including Lindsey Ridlon, Althea Hicks, Megan Knowles and Sean McAuley. Have questions, comments or suggestions about the program? Please call or email us.

SITUATION
Many farms will be finishing up corn harvest this week or next, as more hot, humid weather has hastened corn maturity and shortened the harvest season. Recent weather fronts from the west and south have brought a major flight of corn earworm and, to a lesser extent, fall armyworm into the state, most notably in southern and coastal sites. As a result, any late silking corn remaining will need to be protected regularly and often until the silks are completely dry.

European corn borer:  Although we started removing borer traps from fields last week, farms with traps remaining showed very little activity. Single moths were caught in traps in North Berwick, Wells and Sabattus. No sites were over the 15% spray threshold for larval feeding damage. Here’s another reminder to plow down your corn stalks after harvest. Plowing down the stalks destroys overwintering sites for European corn borer.

Corn earworm:  This week saw a significant jump in the number of moths found in our traps, indicating a severe threat to any silking corn remaining. Southern and coastal sites are being hardest hit, with some traps capturing over 100 moths. A 6-day spray interval for silking corn was recommended for Lewiston and Palmyra. A 5-day spray interval was recommended for Levant. A 4-day spray interval was recommended for silking fields in Charleston, Corinth, Dayton, Monmouth, New Gloucester, Nobleboro, Oxford, Poland Spring, Sabattus, Wayne and Wells. A 3-day spray interval was recommended for North Berwick, Biddeford and Cape Elizabeth.

Fall armyworm:  Armyworm moth numbers were higher at nearly all locations this week, similar to corn earworm. Fields in Biddeford, Cape Elizabeth, Dayton, Levant, Lewiston, Monmouth, New Gloucester, Nobleboro, North Berwick, Oxford, Poland Spring, Wayne and Wells were all over the three moths per week spray threshold for silking corn.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                 UMaine Extension Diagnostic Research Lab
P.O. Box 179                        Pest Management Unit
52 U.S. Route 202              17 Godfrey Drive
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
Recommendations / Comments
Biddeford 149 0 26 3-day spray interval recommended on all silking corn
Bowdoinham 1 2 No spray recommended
Cape Elizabeth I 113 0 23 3-day spray interval recommended on all silking corn
Cape Elizabeth II 500+ 121 3-day spray interval recommended on all silking corn
Charleston 15 0 0 4-day spray interval recommended on all silking corn
Corinth 13 0 0 4-day spray interval recommended on all silking corn
Dayton 73 0 19 4-day spray interval recommended on all silking corn
Levant 5 0 4 5-day spray interval recommended on all silking corn
Lewiston 2 0 8 6-day spray interval recommended on all silking corn
Monmouth 15 10 4-day spray interval recommended on all silking corn
New Gloucester 75 41 4-day spray interval recommended on all silking corn
Nobleboro 11 4 4-day spray interval recommended on all silking corn
North Berwick 112 1 3-day spray interval recommended on all silking corn
Oxford 8 96 4-day spray interval recommended on all silking corn
Palmyra 2 1 0 6-day spray interval recommended on all silking corn
Poland Spring 71 6 4-day spray interval recommended on all silking corn
Sabattus 11 1 1 4-day spray interval recommended on all silking corn
Wayne 36 13 4-day spray interval recommended on all silking corn
Wells I 11 0 1 4-day spray interval recommended on all silking corn
Wells II 64 0 38 4-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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: Corn Field Plowed Down

Image Description: Oats Cover Crop

Image Description: Corn Earworm Feeding on Corn

Image Description: Fall Armyworm Eggs on Corn

Sweet Corn IPM Newsletter No. 10 – August 31, 2018

Sweet Corn IPM Newsletter No. 10 – August 31, 2018
Click on photos to enlarge.

CORN EARWORM, FALL ARMYWORM COUNTS LOWER

Most Silking Fields Still Require Protection

SITUATION
More hot, humid weather continues to push corn development ahead.  Most remaining fields are silking or ready to harvest as the holiday weekend approaches. Insect pressure was more variable this week, with moth counts generally down, but still high enough to warrant protection in nearly all silking fields. Growers continue to report problems with worms getting through their spray programs.

European corn borer:  Moth activity continues to decline this week. Moths were over the spray threshold for silking corn only in Sabattus, however this field was also on a spray interval for corn earworm. Feeding damage was very light, with no sites over the 15% spray threshold for pre-tassel to silking corn. Remember to plow down your corn stalks after harvest. Plowing down the stalks destroys overwintering sites for European corn borer.

Corn earworm:  Moth counts were down in most locations this week, but most sites still require a regular spray interval for silking corn. A 6-day spray interval for silking corn was recommended for Dayton, one Lewiston site, and one Wells site. A 5-day spray interval was recommended for Biddeford, Levant, Nobleboro, North Berwick, Wayne and one Wells site. A 4-day spray interval was recommended for silking fields in Cape Elizabeth, Monmouth, New Gloucester, Poland Spring, and Sabattus.

Fall armyworm:  Moth counts were lower in most locations this week, although many sites were still over the spray threshold for silking corn. Fields in Biddeford, Cape Elizabeth, Monmouth, New Gloucester, North Berwick, Oxford and Wayne were all over the three moths per week spray threshold for silking corn. However, with the exception of the Oxford site, all of them were already following a recommended spray interval for corn earworm. Some growers who have reported problems with getting good control of both fall armyworm and corn earworm with their typical insecticide (usually a pyrethroid, class 3A) have been trying products with different active ingredients, and finding improved control.  Hot, sunny weather can significantly shorten the residual life of some pesticides, including pyrethroid types.  Growers should consider shortening the spray application interval or rotating to a different chemical class if corn is infested despite control efforts.

There’s still time for cover crops!
Plowing down corn stalks and stubble is an important means of managing European corn borer by destroying their over wintering sites. However, late plowing can leave soil exposed and prone to erosion during the winter and spring. Planting winter rye is a good alternative for many fields. Winter rye can often be planted well into September and still produce enough of a cover to prevent erosion. This grass will survive the winter and put on more growth in the early spring. It should be killed by plowing, mowing or herbicide before it goes to seed.  Bear in mind that having rye on the field may delay planting in the spring, as you must wait for conditions to be warm and dry enough to plow it in.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                  UMaine Extension Diagnostic
P.O. Box 179                         Research Lab, Pest Mgmt. Unit
52 U.S. Route 202               17 Godfrey Drive
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 7 0 7 4% 5-day spray interval recommended on all silking corn
Bowdoinham 0 0 0 0% No spray recommended
Cape Elizabeth I 19 0 12 4-day spray interval recommended on all silking corn
Cape Elizabeth II 26 2 4 4-day spray interval recommended on all silking corn
Charleston 1 0 0 No spray recommended
Corinth 1 0 1 No spray recommended
Dayton 2 0 1 6-day spray interval recommended on all silking corn
Farmington 1 0 0 No spray recommended
Levant 6 1 1 5-day spray interval recommended on all silking corn
Lewiston I 3 0 0 6-day spray interval recommended on all silking corn
Lewiston II 1 0 0 No spray recommended
Monmouth 13 7 4-day spray interval recommended on all silking corn
New Gloucester 16 0 5 4-day spray interval recommended on all silking corn
Nobleboro 4 0 1 5-day spray interval recommended on all silking corn
North Berwick 5 0 6 0% 5-day spray interval recommended on all silking corn
Oxford 0 0 17 20% Spray recommended for FAW
Palmyra 0 0 0 No spray recommended
Poland Spring 37 0 1 4-day spray interval recommended on all silking corn
Sabattus 9 9 0 4-day spray interval recommended on all silking corn
Wayne 6 0 3 5-day spray interval recommended on all silking corn
Wells I 2 0 0 6-day spray interval recommended on all silking corn
Wells II 4 1 1 5-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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: Corn Field Plowed Down

Image Description: Fall Army Worm on Pre-tassel Corn Plant

Sweet Corn IPM Newsletter No. 9 – August 24, 2018

Sweet Corn IPM Newsletter No. 9 – August 24, 2018
Click on photos to enlarge.

CORN EARWORM PRESSURE REMAINS HIGH

All Late Silking Corn Requires Protection

SITUATION
Weather has continued to be good for both corn growth and pest populations.  More hot, humid weather predicted for the next several days will likely keep pest pressure at a high level; so, growers with fresh silking corn should remain vigilant and keep the silks protected until they have dried.

European corn borer:  With the exception of fields in Cape Elizabeth and Sabattus, moth activity was low this week. The five moths per week threshold was exceeded at one Cape Elizabeth site and Sabattus. However, both of these sites were also under a spray interval for corn earworm, which should also protect against corn borer. Feeding damage was very light, with no sites over the 15% spray threshold for pre-tassel to silking corn.

Corn earworm:  Moths were widespread and in higher numbers in some locations this week, so sprays were recommended for nearly all silking fields. A 6-day spray interval for all silking corn was recommended for Charleston, one Lewiston site, and Sabattus. A 5-day spray interval was recommended for Bowdoinham, Dayton, Levant, Monmouth, Palmyra, Wayne and one Wells site. A 4-day spray interval was recommended for silking fields in Biddeford, Cape Elizabeth, Corinth, Dayton, one Lewiston site, North Berwick, Nobleboro, Oxford, Poland Spring, and one Wells site.

Fall armyworm:  Although we did not catch moths at all locations, counts exceeded the spray threshold for silking corn where we did catch them with only one exception. Fields in Biddeford, Cape Elizabeth, Monmouth, Oxford, Poland Spring, Wayne and Wells were all over the three moths per week spray threshold for silking corn; but all of these sites were also on a recommended spray interval for corn earworm. On younger corn, larval feeding damage was over the 15% control threshold in Cape Elizabeth, Dayton, North Berwick and Oxford.

When Should You Stop Spraying?
When a silking corn field is under a recommended spray interval for corn earworm, we usually recommend that spraying be stopped once the silks have become thoroughly dried and brown. At this stage, corn earworm moths are unlikely to lay eggs on it. However, if earworm pressure is very high (e.g. 91+ moths per week) and/or fall armyworm moths are over threshold (3 or more moths per week), then spraying should probably continue until either the moth counts drop or you reach the required days before harvest (dh) for the product being used.

Birds, etc.: Flocking species of blackbirds are starting to cause damage in cornfields around the state. They are especially attracted to fields where corn has been allowed to get over-mature. Deer, skunks and raccoons have also been troublesome this year. For information on wildlife problems and management options, you may call the USDA Animal and Plant Health Inspection Service (APHIS) office in Augusta at 1.866.487.3297.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      UMaine Extension Diagnostic Research Lab
P.O. Box 179                             Pest Management Unit
52 U.S. Route 202                   17 Godfrey Drive
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 12 0 7 3% 4-day spray interval recommended on all silking corn
Bowdoinham 4 0 0 0% 5-day spray interval recommended on all silking corn
Cape Elizabeth I 30 0 37% 4-day spray interval recommended on all silking corn
Cape Elizabeth II 67 29 3 15% 4-day spray interval recommended on all silking corn
Charleston 3 0 0 6-day spray interval recommended on all silking corn
Corinth 12 1 1 4-day spray interval recommended on all silking corn
Dayton 7 0 0 15% 5-day spray interval recommended on all silking corn
Farmington 1 0 0 0% No spray recommended
Levant 4 0 0 5-day spray interval recommended on all silking corn
Lewiston I 15 0 0 4-day spray interval recommended on all silking corn
Lewiston II 2 0 0 6-day spray interval recommended on all silking corn
Monmouth 4 8 4% 5-day spray interval recommended on all silking corn
Nobleboro 11 0 0 4-day spray interval recommended on all silking corn
North Berwick 23 0 0 16% 4-day spray interval recommended on all silking corn
Oxford 13 0 8 20% 4-day spray interval recommended on all silking corn
Palmyra 5 3 0 5-day spray interval recommended on all silking corn
Poland Spring 31 0 4 0% 4-day spray interval recommended on all silking corn
Sabattus 2 5 0 6-day spray interval recommended on all silking corn
Wayne 6 0 4 8% 5-day spray interval recommended on all silking corn
Wells I 7 0 0 5-day spray interval recommended on all silking corn
Wells II 23 2 7 4% 4-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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: Corn Earworm Moth

Image Description: Male Fall Armyworm Moth

Image Description: Bird Damage on Corn

Sweet Corn IPM Newsletter No. 8 – August 17, 2018

Sweet Corn IPM Newsletter No. 8 – August 17, 2018
Click on photos to enlarge.

FALL ARMYWORM, CORN EARWORM PRESSURE HIGH

Growers Report Difficulty Controlling Fall Armyworm

SITUATION
Warm weather continued to push corn development this week. Late-planted fields are mostly silking, and will be ready for the post-Labor Day market. We have had several cases of growers finding worm-infested ears in corn that either has been sprayed, or had not yet had a spray recommendation based on pheromone trap captures and field scouting. The damage appears to be from fall armyworm. We may have a type that is not well-matched to the pheromone bait we are using, and may have more tolerance to the pesticides that are typically being used.

European corn borer:  Moth activity increased at some sites this week, threatening silking corn in those fields. The five moths per week threshold was exceeded in Biddeford, one Dayton site, one Lewiston site, and Sabattus. However, all of these sites, except for Sabattus, were also under a spray interval for corn earworm, which should also protect against corn borer. Feeding damage was very light, with no sites over the 15% spray threshold for pre-tassel to silking corn.

Corn earworm:  Moths caught in traps were generally more widespread and in higher numbers this week, and sprays were recommended for nearly all silking fields. A 6-day spray interval for all silking corn was recommended for Corinth, one Lewiston site, Oxford, Palmyra and one site in Wells. A 5-day spray interval was recommended for Biddeford, Levant and New Gloucester. A 4-day spray interval was recommended for silking fields in Cape Elizabeth, Charleston, Dayton, one Lewiston site, North Berwick, Nobleboro, Wayne and one Wells site.

Fall armyworm:  Moth captures continue to be sporadic around the state, but are generally increasing and more widespread. Our fields in Biddeford, Cape Elizabeth, Corinth, Dayton, New Gloucester, Nobleboro, Oxford, Poland Spring and Wells were all over the three moths per week spray threshold for silking corn; but all of the sites were already on a recommended spray interval for corn earworm, with the exception of Poland Spring. With several farms now reporting infested ears at sites where few, if any moths were caught, we are recommending that growers protect any tassel-silking corn that has not yet been sprayed. It may be that the pheromone being used in our traps is not working well with the moths that have come into the state this year. As we reported last week, fall armyworm has been the most challenging species to trap in the past, and in some years the traps have not adequately predicted the damage we found to the ears. Growers are also reporting some infestation regardless of spraying, suggesting that the materials being used in the sprays are not performing well. We recommend that if you have seen problems with insecticide efficacy, you try changing the chemistry of the products you are using. For example, if you have using only synthetic pyrethroids (Warrior®, Bifenthrin®, group 3A), you should try a product in another chemical group, such as Coragen® or Belt SC® (Group 28). Evening sprays may also be more effective as the larvae tend to be more active and exposed at night.

On younger corn, fall armyworm damage was over the 15% control threshold in Biddeford and New Gloucester, although most sites had larvae feeding.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      UMaine Extension Diagnostic Research Lab
P.O. Box 179                             Pest Management Unit
52 U.S. Route 202                   17 Godfrey Drive
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 6 6 22 28% 5-day spray interval recommended on all silking corn
Bowdoinham 1 0 0 2% No spray recommended
Cape Elizabeth 9 2 6 3% 4-day spray interval recommended on all silking corn
Charleston 8 0 0 4-day spray interval recommended on all silking corn
Corinth 2 0 8 0% 6-day spray interval recommended on all silking corn
Dayton I 32 6 5 2% 4-day spray interval recommended on all silking corn
Dayton II 15 0 0 8% 4-day spray interval recommended on all silking corn
Farmington 0 3 0 0% No spray recommended
Levant 5 0 2 1% 5-day spray interval recommended on all silking corn
Lewiston I 22 0 2 4-day spray interval recommended on all silking corn
Lewiston II 2 5 0 6-day spray interval recommended on all silking corn
New Gloucester 7 1 9 18% 5-day spray interval recommended on all silking corn
North Berwick 38 0 0 3% 4-day spray interval recommended on all silking corn
Nobleboro 23 2 6 9% 4-day spray interval recommended on all silking corn
Oxford 2 0 6 5% 6-day spray interval recommended on all silking corn
Palmyra 2 2 0 0% 6-day spray interval recommended on all silking corn
Poland Spring 0 0 3 11% One spray for FAW on all silking corn
Sabattus 1 19 0 One spray for ECB on all silking corn
Wayne 9 0 0 4-day spray interval recommended on all silking corn
Wells I 3 0 0 6% 6-day spray interval recommended on all silking corn
Wells II 32 3 5 10% 4-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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

 

Image Description: Sweet Corn

Image Description: Corn Earworm

Image Description: Fall Armyworm on Corn Leaf

Sweet Corn IPM Newsletter No. 7 – August 10, 2018

Sweet Corn IPM Newsletter No. 7 – August 10, 2018
Click on photos to enlarge.

CORN EARWORM, FALL ARMYWORM THREAT INCREASES

Silking Corn Fields Require Protection

SITUATION
All but the latest planted fields are now silk or beyond. Storm fronts approaching from the south and west have brought up more corn earworm and some fall armyworm to threaten fields with silking corn. Fall armyworm can be troubling at this time, as eggs laid on silking corn allow larvae to move into the ears undetected by field scouting.

European corn borer:  Moth activity declined in most locations this week, with the exception of a site in Sabattus. The five moths/week threshold was only exceeded in Sabattus and one Wells site. However, both of these sites were also under a spray interval for corn earworm, which should also protect against corn borer. Feeding damage was very light, with no sites over the 15% spray threshold for pre-tassel to silking corn.

Corn earworm:  Numbers of moths caught in traps increased at many sites this week, leading to sprays recommended for nearly all silking fields. A 6-day spray interval for all silking corn was recommended for one site in Wells. A 5-day spray interval was recommended for Bowdoinham, Charleston, one Lewiston site, Palmyra, Sabattus and Wayne. A 4-day spray interval was recommended for silking fields in Biddeford, Cape Elizabeth, Dayton, Levant, and one Wells site.

Fall armyworm:  We have started catching moths in our pheromone traps this week, but these have not yet been widespread. This species has historically been the most challenging to trap, and in some years the traps have performed poorly in terms of predicting the damage we find in the field and ears. This may be the situation this season as we have heard from a grower of ears being infested, despite no captures of moths in our traps. This is why we recommend growers consider applying an insecticide when the corn is in the late pre-tassel to tassel/early silk stage, especially if any moth activity or feeding damage has been observed in the field, because this is often when caterpillars are most exposed, as they move from one part of the plant to another. It is also the time when protection of the emerging silk is most critical to prevent infestation. Furthermore, fall armyworm larvae can be difficult to control despite regular sprays, as they tend to be more resistant to many of the insecticides used in corn than the other species we target. Remember, the larvae also tend to be more exposed at night, making evening sprays more effective. The addition of a spreader-sticker with the insecticide can also help to get the best coverage possible and extend the effective time of the application.

Corn leaf aphids: These insects often infest corn plants later in the season, especially in fields that have not recently been sprayed for other pests. Colonies of bluish-green aphid can cover tassels, stalks and husks. Their waste encourages the dark, slimy sooty mold fungus, which covers the surface of the husks. Sprays for corn earworm will usually control aphids.

Corn rust:  Rust is a fungus disease that causes reddish-brown pustules on corn leaves and husks, reducing the quality of the ears. A fungicide spray for rust would only be recommended if the infection were noticed in a field prior to tasseling. Later infections are unlikely to cause enough damage to the crop to justify control measures. Materials available to control corn rust include Quadris®, Bravo®, and Quilt®.

Sincerely,

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
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 14 1 0 1% 4-day spray interval recommended on all silking corn
Bowdoinham 5 0 0 4% 5-day spray interval recommended on all silking corn
Cape Elizabeth 65 1 0 0% 4-day spray interval recommended on all silking corn
Charleston 6 0 0 0% 5-day spray interval recommended on all silking corn
Corinth 8 0 2 1% 4-day spray interval recommended on all silking corn
Dayton I 18 0 0 0% 4-day spray interval recommended on all silking corn
Dayton II 28 2 0 0% 4-day spray interval recommended on all silking corn
Farmington 0 2 3 One spray for FAW on all silking corn
Levant 14 0 0 1% 4-day spray interval recommended on all silking corn
Lewiston I 0 2 18 2% One spray for FAW on all silking corn
Lewiston II 4 2 0 5-day spray interval recommended on all silking corn
New Gloucester 1 0 0 1% No spray recommended
Oxford 1 0 5 1% One spray for FAW on all silking corn
Palmyra 6 3 0 0% 5-day spray interval recommended on all silking corn
Sabattus 7 47 5-day spray interval recommended on all silking corn
Wayne 7 2 5 10% 5-day spray interval recommended on all silking corn
Wells I 2 0 0 0% 6-day spray interval recommended on all silking corn
Wells II 50 7 0 6% 4-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.

IPM Web Pages:

UMaine Cooperative Extension Integrated Pest Management
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: Corn Earworm Larvae

Image Description: Fall Armyworm on Corn Silk

Image Description: Aphids on Corn Tassel

Image Description: Rust on Corn

Sweet Corn IPM Newsletter No. 6 – August 3, 2018

Sweet Corn IPM Newsletter No. 6 – August 3, 2018
Click on photos to enlarge.

CORN EARWORM THREATENS ALL SILKING CORN

Most Sites Now Have Significant Moth Populations in Silking Corn

SITUATION
As predicted, the warm weather from the south has brought an increase in insect activity, as we come into the peak of the sweet corn season. Growers should be monitoring their fields regularly and be prepared to protect silking corn from the threat of earworm and corn borer. Fall armyworm is likely to become more of a threat in the coming days.

European corn borer:  Activity in pheromone traps increased in most fields this week, although it has not yet led to a noticeable increase in feeding damage. This will likely follow soon however, as the eggs these moths are laying begin to hatch. When more than 5 moths are caught in a trap in a week, a spray is recommended for all silking corn to prevent larvae from entering the ears directly after hatching. Moths exceeded this threshold in Bowdoinham, Garland, Lewiston, New Gloucester, Oxford and Wells. However, all of these sites, except the one Wells field, were also under a spray interval for corn earworm, which should also protect against corn borer. Feeding damage in the field was very light, with no sites over the 15% spray threshold for pre-tassel to silking corn; but this is likely to increase soon.

Corn earworm:  Numbers of moths caught in traps increased significantly at nearly all sites monitored this week, leading to sprays recommended for corn in most silking fields. A 6-day spray interval for all silking corn was recommended for our sites in Bowdoinham, one Lewiston site, North Berwick, and Oxford. A 5-day spray interval was recommended for one Cape Elizabeth site, Dayton, Garland, one Lewiston site, Nobleboro, Poland, Sabattus and Wayne. A 4-day spray interval was recommended for silking fields in Biddeford, one Cape Elizabeth site, one Dayton site, Levant, New Gloucester, and one Wells site. At this point, it is likely corn earworm pressure will continue and growers should be prepared to protect all silking corn.

Fall armyworm:  No moths were caught in our pheromone traps this week, but we anticipate we will be seeing them soon because we are finding some larval feeding. None of the injury was over the 15% spray threshold.

Squash vine borer:  Moths were over the 5 moth per week threshold in Oxford. All other sites had either one or no moths this week.

Spotted wing drosophila:  Fly counts have been variable this week, with some locations seeing increases (Limington, Readfield) while most locations still had very few, if any flies. The recent heat and rain will improve conditions for spotted wing drosophila (SWD), because they likely increased the amount of rotten fruit in the field and the level of moisture. Both are conducive to fly presence and reproduction. Try keep the planting as free from rotten fruit as possible, remove excess vegetative growth, especially near the base of the plants, and apply a suitable insecticide when flies are observed or larvae are found in the fruit. For more information visit our SWD blog.

Sincerely,

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
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 8 1 0 0% 4-day spray interval recommended on all silking corn
Bowdoinham 2 16 0 0% 6-day spray interval recommended on all silking corn
Cape Elizabeth I 4 0 0 0% 5-day spray interval recommended on all silking corn
Cape Elizabeth II 24 1 0 4% 4-day spray interval recommended on all silking corn
Charleston 0 2 0 0% No spray recommended
Dayton I 4 0 0 0% 5-day spray interval recommended on all silking corn
Dayton II 8 3 0 2% 4-day spray interval recommended on all silking corn
Farmington 0 2 0 0% No spray recommended
Garland 4 5 0 5-day spray interval recommended on all silking corn
Levant 33 0 0 1% 4-day spray interval recommended on all silking corn
Lewiston I 2 5 0 0% 6-day spray interval recommended on all silking corn
Lewiston II 5 3 0 0% 5-day spray interval recommended on all silking corn
New Gloucester 12 5 0 0% 4-day spray interval recommended on all silking corn
Nobleboro 6 3 5-day spray interval recommended on all silking corn
No. Berwick 3 2 0 1% 6-day spray interval recommended on all silking corn
Oxford 2 15 0 0% 6-day spray interval recommended on all silking corn
Palmyra 0 3 0 0% No spray recommended
Poland 5 0 0 5-day spray interval recommended on all silking corn
Sabattus 6 2 0 5-day spray interval recommended on all silking corn
Wales 1 1 0 0% No spray recommended
Wayne 4 0 0 0% 5-day spray interval recommended on all silking corn
Wells I 0 28 0 1% One spray for ECB on all silking corn
Wells II 14 2 0 0% 4-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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

 

Image Description: Sweet Corn

Image Description: European Corn Borer Larva

Image Description: Corn Earworm Feeding on Corn

Image Description: Male Spotted Wing Drosophila

Sweet Corn IPM Newsletter No. 5 – July 27, 2018

Sweet Corn IPM Newsletter No. 5 – July 27, 2018
Click on photos to enlarge.

CORN EARWORM NUMBERS CLIMBING

Populations Spotty, but Some Fields Severely Threatened

SITUATION
Corn harvest is coming into full swing for early varieties in southern and mid-coast farms. Warm weather has pushed maturity of later varieties, so we may see some concentration of maturity in the coming days. Warm air and rain coming up from the south over the past week has brought some corn earworm into the state, but not yet to the levels we expected. The warm air flow continues, however; so it is likely that pest pressure will increase in the coming days.

European corn borer:  Activity in both pheromone traps and the fields remained very low this week. We did find pupae in stalks, which may indicate that we could see a second generation of corn borer this year that might threaten late corn. Moths were caught in Biddeford, Cape Elizabeth, Dayton, Lewiston, North Berwick, Oxford, and Wales. They were below threshold for silking corn at all of these sites. Feeding damage in the field was very light, with no sites over the 15% spray threshold for pre-tassel to silking corn.

Corn earworm:  Numbers of moths caught in traps this week were quite variable and didn’t seem to follow any geographic pattern. A 6-day spray interval for all silking corn was recommended for our sites in Biddeford, Cape Elizabeth and Sabattus. A 5-day spray interval was recommended for Bowdoinham and Garland. A 4-day spray interval was recommended for a silking field in Levant. As the weather for the coming week is predicted to continue coming up from the south, we should expect corn earworm pressure to continue and be prepared to protect all silking corn.

Fall armyworm:  No moths were caught in our pheromone traps this week, but we have found some larval feeding damage in the cornfields we’ve scouted. This is not unusual; our traps often don’t catch the first moths into the fields, so we see feeding injury before we see moths. No feeding injury was over the 15% spray threshold. We also continue to see a small amount of feeding injury from common army worm, but we expect these larvae to be pupating very soon. The anticipated weather pattern could bring a rapid increase in fall armyworm numbers in the coming days.

Squash vine borer moths were caught in pheromone traps in Biddeford, Lewiston, Wells and Oxford. Only the Oxford site, which had 5 moths, was over the spray threshold. All other sites were below the spray threshold, Counts may still increase in the coming days, so growers should continue scouting for vine borer symptoms and protect squash plants if moths or damage are seen. See the 2018-2019 New England Vegetable Management Guide for control options.

Spotted wing drosophila:  We continue to capture spotted wing drosophila (SWD) flies around the state, but still in relatively low numbers. We have had reports of larval infestation of unsprayed raspberry fruit, so growers who have been capturing flies in traps for more than one week should protect ripening fruit, if sprays have not yet been applied. For more information visit our SWD blog.

Sincerely,

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
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 3 3 0 0% 6-day spray interval recommended on all silking corn
Bowdoinham 4 0 0 0% 5-day spray interval recommended on all silking corn
Cape Elizabeth I 0 0 0 0% No spray recommended
Cape Elizabeth II 2 2 0 6-day spray interval recommended on all silking corn
Charleston 0 0 0 0% No spray recommended
Dayton I 0 0 0 0% No spray recommended
Dayton II 0 2 0 2% No spray recommended
Farmington 0 0 0 0% No spray recommended
Garland 6 0 0 1% 5-day spray interval recommended on all silking corn
Levant 29 0 0 3% 4-day spray interval recommended on all silking corn
Lewiston I 0 0 0 0% No spray recommended
Lewiston II 1 1 0 0% No spray recommended
New Gloucester 0 0 0 0% No spray recommended
No. Berwick 0 1 0 3% No spray recommended
Oxford 1 1 0 3% No spray recommended
Palmyra 0 0 0 0% No spray recommended
Poland 1 0 0 2% No spray recommended
Sabattus 2 0 0 0% 6-day spray interval recommended on all silking corn
Wales 0 2 0 1% No spray recommended
Wayne 0 0 0 1% No spray recommended
Wells I 0 0 0 4% No spray recommended
Wells II 1 0 0 4% 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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
Penn State Pest Watch for Sweet Corn
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: European Corn Borer in Tassel

Image Description: Fall Armyworm Injury on Corn Leaves

Image Description: Squash Vine Borer Larva

Sweet Corn IPM Nesletter No. 4 – July 20, 2018

Sweet Corn IPM Newsletter No. 4 – July 20, 2018
Click on photos to enlarge.

LOW INSECT ACTIVITY CONTINUES

Storms Expected Next Week May Bring Pests into Maine

SITUATION
Some welcome rain fell on dry corn fields this week, followed by more warm weather. As a result, we are seeing rapid corn development in the fields. Early harvest has begun in some transplanted and mulched fields. Corn pest activity continues to be very low in cornfields this week, so very few fields have needed sprays. Weather predictions for the coming week indicate warm air and moisture coming up from the south, which may bring in significant numbers of corn earworm and fall armyworm.

European corn borer:  There was very little borer activity in both pheromone traps and fields this week. Moths were only caught in three locations: Cape Elizabeth, Dayton and Wales. They were below threshold for silking corn at all of these sites. Feeding damage was also light, with only one field in Oxford being over the 15% spray threshold for pre-tassel to silking corn.

Corn earworm:  No moths were caught in our pheromone traps this week, and therefore no sprays were recommended. There is more silking corn available for earworm moths to lay eggs on this week, so the threat is increasing. Growers should be alert for changes in the weather, such as storms moving in from southern states, that could bring more corn earworm into Maine.

Fall armyworm:  No moths were caught in our pheromone traps this week, and we have not yet found any feeding damage in the cornfields we’ve scouted. We have found a few common armyworms within corn plants behaving much like fall armyworm. However, these larvae will be pupating very soon and are not likely to get into the ears. Like corn earworm, the situation for fall armyworm could change rapidly with weather coming up from the south next week.

Squash vine borer moths were caught in pheromone traps in Biddeford, New Gloucester, Lewiston, Nobleboro, Farmington and Oxford this week. Only the Oxford site, which had 11 moths, was over the 5-moth spray threshold. All other sites were below the spray threshold, but we expect counts to increase state wide in the coming days. Growers with squash in southern Maine should be scouting for vine borer symptoms and protect squash plants if moths or damage are seen. See the 2018-2019 New England Vegetable Management Guide for control options.

Japanese beetles are now appearing in southern and mid-state areas. These insects often find their way into cornfields and feed on the leaves, causing an interveinal skeletonizing, which is generally not significant. However, they may also feed on the silks of developing ears, causing poor tip fill. Sprays for European corn borer and/or corn earworm (except Bt’s) usually will control Japanese beetle as well.

Spotted wing drosophila:  The first capture of spotted wing drosophila (SWD) occurred this week in berry fields in southern Maine. These small fruit flies can cause serious fruit losses in raspberries, blueberries and other soft fruits. This pest has already reached damaging numbers throughout much of New England, which is about 2-3 weeks ahead of what we have seen in the past few years.  For more information visit our SWD blog.

Sincerely,

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
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 0 0 0 9% No spray recommended
Bowdoinham 0 0 0 1% No spray recommended
Cape Elizabeth I 0 3 0 0% No spray recommended
Cape Elizabeth II 0 0 0 6% No spray recommended
Dayton 0 3 0 0% No spray recommended
Farmington 0 0 0 9% No spray recommended
Lewiston I 0 0 0 0% No spray recommended
Lewiston II 0 0 0 0% No spray recommended
Nobleboro 0 0 0 No spray recommended
No. Berwick 0 0 0 0% No spray recommended
Oxford 0 0 0 19% One spray recommended for ECB feeding damage
Sabattus 0 0 0 11% No spray recommended
Wales 0 1 0 0% No spray recommended
Wayne 0 0 0 4% No spray recommended
Wells I 0 0 0 4% No spray recommended
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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
Penn State Pest Watch for Sweet Corn
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: Squash Vine Borer Larva

Image Description: Japanese Beetle

Image Description: Male and Female Spotted Wing Drosophila Flies

Sweet Corn IPM Newsletter No. 3 – July 13, 2018

Sweet Corn IPM Newsletter No. 3 – July 13, 2018
Click on photos to enlarge.

LOW INSECT ACTIVITY IN CORNFIELDS

Few Moths or Damage Found This Week

SITUATION
Warm, dry weather continues to move corn development rapidly throughout the state, and many early fields are or will be silking within the next few days. Adequate irrigation is key to good ear fill during the silking stage if rainfall has been lacking. Drought stressed corn will often have very poor ear size and fill.  Insect activity in cornfields was very low this week, perhaps related to cooler nighttime temperatures.

European corn borer:  Very few moths were caught in pheromone traps this week, and only along the southern coast. Larval feeding damage was also below threshold in all fields scouted, as sprays applied over the past week have cleaned up fields that were recently over threshold. Some early fields are now silking, and when corn reaches that stage, sprays can be based on the number of corn borer moths caught in pheromone traps rather than feeding injury. However, none of our sites exceeded the 5 moth per week spray threshold.

Corn earworm:  A single moth was caught in a pheromone trap in Lewiston this week. A spray was not recommended, even when some silking corn was present. Once more than one moth per week is captured in a silking field, a spray interval will be recommended, based on the number of moths being caught. There is still not much silking corn available for earworm moths to lay eggs on, so the threat remains low. Warmer evening temperatures and any weather fronts moving into Maine from the south could change the situation rapidly; although, as of this week, low earworm activity is also being reported from states to our south.

Fall armyworm:  No moths were caught in our pheromone traps this week, and we have not yet found any feeding damage in the cornfields we’ve scouted. As with corn earworm, however, this situation could change rapidly if weather fronts from the south move into the state.

Squash vine borer moths were caught in pheromone traps in Biddeford, Lewiston and Oxford this week. Counts were below the spray threshold, but indicate that this pest will threaten squash and pumpkins this season. Moth counts in New Hampshire are over threshold this week, so activity here will rise soon. Squash vine borer moths are black and orange and resemble wasps. They lay their eggs at the base of squash plants. The larvae bore into the base of the plants, causing vines to wilt and collapse. Growers with squash in southern Maine should be on the lookout for vine borer symptoms and protect squash plants if moths or damage are seen. See the 2018-2019 New England Vegetable Management Guide for control options.

Potato leafhopper alert:  potato leafhopper is now active in vegetable and strawberry fields. These small, bullet-shaped insects feed on plant sap from the undersides of leaves, causing the leaves to become curled, stunted and yellow-streaked. Beans are often the first crop to show symptoms, but other crops are also susceptible, including potatoes and strawberries. To scout for leafhoppers, brush the leaves of the plants with your hand. The small, whitish adults can be seen flying off the plant. Look for small, light green leafhopper nymphs on the underside of injured leaves. They are about 1/16-inch long. When touched, they will crawl sideways in a crab-like manner. Control options for potato leafhoppers are listed in the New England Vegetable Management Guide.

Maine State Pomological Society Summer Tour
The event will be held on Wednesday July 18, 2018 at Dole’s Orchard, 187 Doles Ridge Road, Limington, Maine 04048. Earl and Nancy Bunting will be hosting the Maine State Pomological Society Summer Tour at their farm this summer. Much of the focus will be on the tree fruit grown at Dole’s Orchard, including apples and cherries; but there are also large plantings of pic-your-own strawberries, raspberries and blueberries. Some of the fruit is also contracted to a local brewery. There will be a morning educational program, including talks from research and Extension Specialists, followed by lunch and afternoon tours of the fields and orchards led by Earl and Nancy. Plan to come visit this beautiful farm with us! Pre-registration is requested so we know how many lunches to request. Please contact Pam St. Peter at 207.933.2100 or pamela.stpeter@maine.edu for more information.

Two pesticide applicator credits will be offered for attending the summer tour’s full day program. Registration is $15 for Maine State Pomological Society members, and $20 for nonmembers. Registration payments by cash or check will be collected at the event.

Sincerely,

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
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 0 1 0 0% No spray recommended
Cape Elizabeth I 0 3 0 0% No spray recommended
Cape Elizabeth II 0 0 0 4% No spray recommended
Dayton I 0 0 0 6% No spray recommended
Farmington 0 0 0 13% No spray recommended
Lewiston I 0 0 0 0% No spray recommended
Lewiston II 1 0 0 0% No spray recommended (no silking corn)
New Gloucester 0 0 0 0% No spray recommended
Nobleboro 0 0 0 0% No spray recommended
No. Berwick 0 0 0 1% No spray recommended
Oxford 0 0 0 12% No spray recommended
Wales 0 0 0 0% No spray recommended
Wayne 0 0% No spray recommended
Wells I 0 0 0 4% No spray recommended
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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
Penn State Pest Watch for Sweet Corn
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: Two Squash Vine Borer Moths

Image Description: Potato Leafhopper

Image Description: Cornfield at Highmoor Farm

Sweet Corn IPM Newsletter No. 2 – July 6, 2018

Sweet Corn IPM Newsletter No. 2 – July 6, 2018
Click on photos to enlarge.

CORN EARWORM THREATENS EARLY SILKING CORN

European Corn Borer Damage on the Rise

SITUATION
A string of very hot, humid days has pushed corn development along rapidly, especially in irrigated fields.  Hail ripped up young corn in a few fields, but young corn is likely to recover from the damage. Transplanted corn and some seeded under plastic mulch is silking in southern Maine, indicating that the start of harvest could be only two to three weeks away. The hot weather has also stimulated more insect activity, as we have found a couple of fields over threshold for European corn borer damage, and a couple of early corn earworm moths in traps along the coast.

European corn borer:  Moths were caught in pheromone traps in southern and coastal sites this week, and larval feeding damage is showing up on whorl to tassel stage corn. In whorl stage corn the control threshold is 30% of plants showing feeding injury. Once the plants reach the pre-tassel stage the threshold is lowered to 15%, because larvae at this stage are more likely to damage the ears. Pre-tassel fields in Biddeford, Bowdoinham and Dayton were over control threshold for pre-tassel corn, so sprays were recommended. Sprays during the pre-tassel stage, when both moths and larvae are present, target the larvae before can they move into the protection of the stalks and ears. Once corn reaches the silk stage, sprays may be based on the number of corn borer moths caught in pheromone traps rather than feeding injury. If more than 5 moths are caught in pheromone traps in a week near silking corn, a spray is recommended to prevent moths from laying eggs on the flag leaves of the ears, which could lead to larvae infesting the ears while leaving no visible signs of feeding on the leaves. So far, none of the silking fields have been over the 5-moth threshold.

Corn earworm:  Moths were caught in pheromone traps at two coastal locations, Cape Elizabeth and Nobleboro. Both of these captures were single moths, which does not trigger a spray, even if silking corn is present. Once more than one moth per week is captured in a silking field, a spray interval would be recommended, based on the number of moths being caught. The more moths caught, the more frequently the silking corn will need to be sprayed to adequately protect it. (See table below.) At present, there is very little silking corn available for earworm moths to lay eggs on, so the threat is low for most fields. When no silking corn is available, corn earworm moths may lay eggs on corn leaves, and the larvae will chew large, ragged holes in the leaves, similar to fall armyworm.

Fall armyworm:  No moths have been captured in our pheromone traps this week, and no feeding damage has been reported. Although this is usually the last major corn pest to arrive in Maine from southern overwintering sites, it often follows corn earworm closely, and was the most significant pest problem in most corn fields for the past two seasons.

Common armyworm is often found chewing on early corn. Like fall armyworm, this caterpillar chews large holes in whorl to pre-tassel corn. The larvae are light brown with yellow and black stripes running along the body. This insect overwinters in Maine and is usually only present early in the season. Young corn can often outgrow the injury. However, heavy infestations can occur and may require control. We have found some common armyworm in western Maine this week, but not at significant levels.

Sincerely,

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
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 0 1 0 23% One spray for ECB on pre-tassel corn
Bowdoinham 0 0 0 15% One spray for ECB on pre-tassel corn
Cape Elizabeth I 0 3 0 4% No spray recommended
Cape Elizabeth II 1 4 0 4% No spray recommended (corn not yet silking)
Dayton I Set up Set up Set up 16% One spray for ECB on pre-tassel to silking corn
Farmington 0 0 0 0% No spray recommended
Lewiston I 0 0 0 4% No spray recommended
Lewiston II Set up Set up Set up 0% No spray recommended
New Gloucester 0 0 0 0% No spray recommended
Nobleboro 1 2 0 13% No spray recommended
No. Berwick Set up Set up Set up 14% No spray recommended
Oxford 0 0 0 15% One spray for ECB on pre-tassel corn
Wayne 0 0 0 0% No spray recommended
Wells I Set up Set up Set up 0% No spray recommended
Wells II Set up Set up Set up 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.

IPM Web Pages:
UMaine Cooperative Extension Integrated Pest Management
Penn State Pest Watch for Sweet Corn
UMass Amherst Integrated Pest Management

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.

The University of Maine is an equal opportunity/affirmative action institution.

Image Description: Sweet Corn

Image Description: European Corn Borer Moth

Image Description: Corn Earworm Moth

Image Description: Male Fall Armyworm Moth


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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