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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
PennState Pestwatch 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:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
https://ag.umass.edu/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:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
https://ag.umass.edu/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

Sweet Corn IPM Newsletter No. 1 – June 29, 2018

Sweet Corn IPM Newsletter No. 1 – June 29, 2018
Click on photos to enlarge.

2018 SWEET CORN PEST SEASON BEGINS!

European Corn Borer Active in Early Fields

The 2018 University of Maine Cooperative Extension Integrated Pest Management (IPM) program for sweet corn is underway. More than twenty volunteer farms are serving as pest monitoring and demonstration sites, with fields in North Berwick, Wells, Dayton, Cape Elizabeth, New Gloucester, Poland Spring, Auburn, Lewiston, Sabattus, Nobleboro, Monmouth, Wales, Wayne, Oxford, Farmington, Levant, Stillwater, Garland and East Corinth. We are setting up pheromone traps at these locations to monitor the adult (moth) stages of European corn borer, corn earworm and fall armyworm, and we are scouting the fields for feeding injury by insect larvae. We will be sharing the information we collect along with management recommendations through this newsletter blog.

SITUATION
A very dry spring has got early corn off to a quick start, in spite of variable temperatures. Early plantings in southern Maine and plots started under plastic or row covers are mostly at pre-tassel, although we have seen a few tassels, and some silking corn in a transplanted field. Late fields are starting to emerge. Early scouting has shown some European corn borer activity in pre-tassel corn, but no damage has been over the spray threshold. With warmer temperatures expected we can expect to see increased activity in the coming days, and weather coming up from the south may also bring our first corn earworm of the season.

European corn borer:  Pheromone traps for moths are set up in the grassy borders around cornfields. We have begun scouting pre-tassel to tasseling fields in southern Maine, and found some early feeding damage in Oxford, Farmington, Wayne and Nobleboro. To monitor corn borer, we scout 100 corn plants in each field, examining twenty plants in a row at five different locations. This provides a good estimate of the total amount of injury in a field.

In the early stages, European corn borer feeding damage looks like small “pinholes” in the leaves. Whorl stage corn only needs to be sprayed if fresh feeding injury is found on 30% or more of the plants scouted in a field. Once the corn reaches the pre-tassel stage, the control threshold is lowered to 15% because larvae feeding on the later stages are more likely to move into the ears. On the tassels, feeding damage first appears as chewing and brown waste found in the small florets. After the tassel has emerged from the whorl, the larvae chew into the stalk just below it, often causing the tassel to fall over. 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. Good spray coverage of the entire plant provides the most effective kill of larvae as they move from one part of the plant to another. Rotating the type of insecticide used also improves control. Materials registered for controlling European corn borer include Bacillus thuringiensis products (XenTari®, Dipel DF®), Avaunt®, Coragen®, Warrior®, Lannate®, Baythroid®, Asana®, Radiant®, Delta Gold®, Mustang®, Sevin XLR® and Intrepid®. Newly hatched European corn borer larvae are very small and translucent with shiny black heads. They emerge from small egg masses that look like a tiny clump of overlapping fish scales on the undersides of corn leaves. European corn borer overwinters in Maine, and is usually the first pest to become a significant problem.

Growers should start scouting whorl stage corn for feeding injury now. 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. European corn borer moths will lay eggs on flag leaves of silking corn, and the larvae can move into the ears without leaving visible feeding injury that would be noticed when scouting. If more than five moths are caught during a week in a field with silking corn, a spray is recommended. Varieties of corn genetically modified to produce the Bt toxin (e.g. Bt corn, Attribute® varieties), should not need to be sprayed to control European corn borer.

Corn earworm:  We have set up pheromone traps around the state for corn earworm moths. Corn earworm generally appears in Maine in early July, but the actual date varies greatly. The arrival of this pest is only a concern for fields with corn in the silk stage. Fields not yet in silk do not need to be protected from corn earworm. When corn earworm moths are caught at a site, all silking corn in the fields should be protected with a spray. These moths lay eggs on the fresh silks, and the larvae move directly into the ears of corn. When corn earworm moths cannot find silking corn to deposit their eggs on, they may lay eggs on the leaves or tassels of younger corn. The larvae will feed on the foliage and tassels, similar to armyworm, until the ears become available. When larvae are found feeding on younger corn, the damage is accounted for, along with any borer or armyworm damage, to determine if a spray is warranted.

Fall armyworm:  This is usually the last serious corn insect pest to arrive in Maine. The moths fly in from southern over-wintering sites, and tend to lay their eggs on the youngest corn available. The young larvae chew large, ragged holes in the leaves, and may bore into developing ears. Larvae can also move into the ears through the silk channel, behaving similarly to corn earworm. Pheromone trap catches will indicate if there is a threat to silking corn. However, corn is often on a spray program for corn earworm when fall armyworm is present, and both insects should be controlled. For the past two years, fall armyworm moths arrived in Maine early in the season, and were often more of a threat than corn earworm. We will be watching fall armyworm closely this year to see if this new, unfortunate trend continues.

Common armyworm:  Be on the lookout for reports of common armyworm attacking silage corn, alfalfa and hayfields. Common armyworm can become active as early as April and can become a problem in early planted sweet corn. However, if the corn is established, it will outgrow the injury, as the caterpillars will pupate before the ears develop. However, when heavy infestations occur, control may be required. Common armyworm larvae are brown with yellow and black stripes running along the body. They chew large, ragged holes in the leaves, similar to fall armyworm.

Northern corn leaf blight:  This fungus disease has become more prevalent across New England in recent years, and growers should monitor fields for the symptoms. Gray to tan cigar-shaped lesions appear on the leaves and stalks, eventually coalescing, causing the leaves to die and dry up. This weakens the plants, reducing yield and quality of the ears. To manage the disease, purchase only varieties that are resistant to leaf blight, rotate out of fields that have had the disease for at least one year, and when necessary apply fungicides when symptoms are first noticed. For more information, including products and rates, consult the New England Vegetable Management Guide.

Do-It-Yourself IPM:  To get the most accurate information about the pest situation on your farm you should monitor the fields yourself on a regular basis. Pheromone traps and lures are available that can give you an accurate, early warning of the arrival of all of the major insect pests. Traps and lures can be purchased from pest management supply companies such as Gempler’s (1.800.382.8473) or Great Lakes IPM (517.268.5693). You may also want to download a copy of our fact sheet Managing Insect Pests of Sweet Corn at our website.

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

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://ag.umass.edu/integrated-pest-management/umass-extension-programs

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: European Corn Borer Damage

Image Description: Corn Earworm Moth

Image Description: Fall Armyworm Moths

Image Description: Northern Corn Leaf Blight

Image Description: European Corn Borer Trap

Image Description: Harstack Trap

Sweet Corn IPM Newsletter No. 13 – September 15, 2017

Sweet Corn IPM Newsletter No. 13 – September 15, 2017
Click on photos to enlarge.

Last Issue for 2017!

INCREASING PEST PRESSURE TO END SEASON

Fresh Silking Corn Remaining Likely to Need Protection

This will be the final issue of the Sweet Corn IPM Newsletter for the 2017 season. I would like to thank all of the growers who participated in the program this year, and our team of IPM scouts, including Kara Rowley, Tammy Cushman, Lindsey Ridlon and Sean McAuley. Have questions, comments or suggestions about the program? Please call or e-mail us.

SITUATION
It appears the tropical fronts and warmer weather pushing through Maine have only brought about a moderate increase in moth activity. There may be more activity associated with tropical storms in the coming weeks, however, so the threat to any fresh silking corn that still remains may increase.

European corn borer:  No moth captures for a second week, so no real threat from European corn borer to end the season. There was no fresh larval feeding injury on younger corn and no sprays for this insect were recommended.

Corn earworm:  Moth counts rose moderately in most locations this week, keeping most fields with any fresh silk remaining on a spray schedule. A 6-day spray interval was recommended for silking corn in Oxford and one Wells site this week. A 5-day spray schedule was recommended in Auburn, one Dayton site and Sabattus. A 4-day spray interval was recommended in Cape Elizabeth, one Dayton location, North Berwick, and one Wells site.

Fall armyworm:  Moth activity was spotty around the state this week, with some sites seeing a slight increase in activity and others not. No sprays were recommended exclusively for fall armyworm on silking corn, because all sites over the 3-moth threshold were on a spray interval for corn earworm, including Cape Elizabeth, Dayton, Oxford and Sabattus. No sites were over the 15% injury threshold for larval feeding damage.

Just a reminder that fall is a great time for soil testing
Late summer and early fall are good times to seed cover crops to prevent soil erosion and to retain soil nutrients. It is also a great time to check on the health of your soil. Getting your soil test results before the ground freezes allows time to correct soil pH with additions of lime, and incorporate any needed supplements into the soil, such as phosphorus, potassium, magnesium or other nutrients to correct deficiencies, and/or manure to increase organic matter. Fall applications of lime and some nutrients (not nitrogen, as it is prone to leaching) are often better, because the fields are drier than in the spring. It’s easier to move equipment around, and the nutrients will have time to be worked into the soil before the plants need them. You can pick up soil test boxes and forms at any county office of the University of Maine Cooperative Extension, or call us here at Highmoor Farm if you’d like us to send you some. For details on soil testing at the University of Maine Analytical Laboratory and Soil Testing Service, you can visit their website at: https://umaine.edu/soiltestinglab/.

The New England Vegetable and Fruit Conference will be held in Manchester, New Hampshire on December 12, 13 and 14, 2017. Program and registration information will be coming soon. Visit the website, http://www.newenglandvfc.org/.

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
Auburn 5 0 0 5-day spray interval recommended on all silking corn
Bowdoinham 1 0 0 0% No spray recommended
Cape Elizabeth I 26 0 17 4-day spray interval recommended on all silking corn
Cape Elizabeth II 16 0 13 0% 4-day spray interval recommended on all silking corn
Dayton I 63 0 13 0% 4-day spray interval recommended on all silking corn
Dayton II 6 0 4 5-day spray interval recommended on all silking corn
Monmouth 1 0 1 0% No spray recommended
North Berwick 11 0 2 4-day spray interval recommended on all silking corn
Oxford 3 0 9 6-day spray interval recommended on all silking corn
Sabattus 5 0 4 5-day spray interval recommended on all silking corn
Wales 1 0 1 0% No spray recommended
Wayne 0 0 0 No spray recommended
Wells I 2 0 2 6-day spray interval recommended on all silking corn
Wells II 10 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 IPM
Penn State Sweet Corn IPM
UMass Extension IPM Programs

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: Fall Armyworm Moths

Sweet Corn IPM Newsletter No. 12 – September 11, 2017

Sweet Corn IPM Newsletter No. 12 – September 11, 2017
Click on photos to enlarge.

CORN PEST THREAT MODERATE BUT VARIABLE

Corn Earworm and Fall Armyworm Active in Silking Corn at Most Sites

SITUATION
Cool nights and some rainy days appear to be holding corn pests at moderate levels for this time of year, as the sweet corn season winds down. However, we may still have the remnants of tropical storms to deal with over the next couple of weeks which could cause an increase in corn earworm and/or fall armyworm populations. Next week will be the last scheduled issue of the Sweet Corn IPM Newsletter for the 2017 season.

European corn borer:  No moth captures this week, suggesting the threat of corn borer may be over for this season. Larval feeding injury on younger corn was also very low, and did not exceed threshold at any location.

Corn earworm:  Overall, moth counts remain fairly low this week, but high enough to keep some sites on a tight spray schedule for any fresh silking corn remaining. A 5-day spray schedule was recommended in Auburn, New Gloucester, North Berwick, and Wells.  A 4-day spray interval was recommended in Biddeford, Cape Elizabeth, one Dayton location, Lewiston, Monmouth and Sabattus.

Fall armyworm:  Moth activity is becoming spottier from site to site, with some locations well over the 3-moth threshold for silking corn, and others seeing few, if any moths. A spray for fall armyworm on silking corn was recommended in one Dayton site, Nobleboro, Poland Spring and Wales. Other sites, including Auburn, Biddeford, Cape Elizabeth, Dayton, Lewiston, Monmouth, North Berwick, and Sabattus were also over the 3-moth threshold, but are on a spray schedule for corn earworm. No sites were over the 15% injury threshold for larval feeding damage in pre-tassel to tassel corn.

Annual end of corn season checklist:

  1. Plow down corn stalks and stubble to destroy overwintering larvae of European corn borer.
  2. Plant a cover crop, such as winter rye, to prevent soil erosion and to add organic matter to the soil.
  3. Take a soil test to determine if lime or other nutrients should be applied.
  4. Plan to rotate your crops to prevent pests from building up in any one location.
  5. Evaluate your weed management results. What worked well and what didn’t?  Which weeds were the biggest problems?  How can you improve control?

The New England Vegetable & Fruit Conference will be held in Manchester, NH on December 12, 13, and 14, 2017. Program and registration information will be coming soon. Visit the website: http://www.newenglandvfc.org/.

Reminder: Free disposal of unusable pesticides
The Maine Board of Pesticides Control (BPC) and the Maine Department of Environmental Protection (DEP) are sponsoring the Obsolete Pesticides Collection Program. This free program is open to homeowners, family-owned farms and greenhouses. Collections of unwanted pesticides will occur at four sites: Presque Isle, Bangor, Augusta, and Portland. Participants must pre-register by September 29, 2017Drop-ins are not permitted. To register, get details, and learn important information about the temporary storage and transportation of obsolete pesticides, go to the Maine BPC web site or call 207.287.2731.

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
Auburn 5 0 10 5-day spray interval recommended on all silking corn
Biddeford 8 0 7 4-day spray interval recommended on all silking corn
Bowdoinham 0 0 0 No spray recommended
Cape Elizabeth I 25 0 38 4-day spray interval recommended on all silking corn
Cape Elizabeth II 8 0 17 4-day spray interval recommended on all silking corn
Dayton I 41 0 107 0% 4-day spray interval recommended on all silking corn
Dayton II 0 0 5 One spray for FAW on all silking corn
Lewiston 15 0 4 4-day spray interval recommended on all silking corn
Monmouth 12 0 9 4-day spray interval recommended on all silking corn
New Gloucester 6 0 0 5-day spray interval recommended on all silking corn
Nobleboro 0 0 42 One spray for FAW on all silking corn
North Berwick 4 0 3 3% 5-day spray interval recommended on all silking corn
Oxford 1 0 2 No spray recommended
Poland Spring 0 0 12 One spray for FAW on all silking corn
Sabattus 14 0 7 4-day spray interval recommended on all silking corn
Wales 0 0 5 One spray for FAW on all silking corn
Wayne 0 0 0 No spray recommended
Wells I 5 0 2 5-day spray interval recommended on all silking corn
Wells II 4 0 2 9% 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 IPM
Penn State Sweet Corn IPM
UMass Extension IPM Programs

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 Feeding on Corn

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

Image Description: Unplowed Corn Field

Image Description: Oats Cover Crop

Sweet Corn IPM Newsletter No. 11 – September 1, 2017

Sweet Corn IPM Newsletter No. 11 – September 1, 2017

Click on photos to enlarge.

COOL NIGHTS SLOW INSECT ACTIVITY

Anticipated Storm Fronts May Increase Moth Counts Next Week

SITUATION
Cool night temperatures have slowed development of late corn, but supply and quality look good for the holiday weekend. Many farms will soon be harvesting their last plantings of the season. The cool temperatures appear to have slowed pest activity as well, although most locations still require some protection on silking corn. The remnants of the tropical storm Harvey may drop rain and moths on Maine this weekend, so we may see a different situation next week.

European corn borer:  Low moth numbers this week, with most locations having caught none, and no locations over the threshold for silking corn. Larval feeding injury on younger corn was also low, but more small larvae were seen in pre-tassel to tasseling corn.

Corn earworm:  Moth counts are fairly low for this time of year in most locations, with several sites catching no moths. However, some sites remain on a tight spray schedule for silking corn. A 6-day spray interval for corn earworm was recommended for silking fields in Garland, Monmouth and Sabattus. A 5-day spray schedule was recommended in Wells. A 4-day spray interval was recommended in Biddeford, Cape Elizabeth, North Berwick, and Poland Spring.

Fall armyworm:  Moth activity remained high at many sites, well over the 3-moth threshold for silking corn. A spray for fall armyworm on silking corn was recommended in Lewiston, Oxford Palmyra and Wales. Other sites, including Auburn, Monmouth, Cape Elizabeth, North Berwick, Poland Spring and Sabattus were also over the 3-moth threshold, but are on a spray schedule for corn earworm. Larval feeding damage in younger corn fields in Cape Elizabeth and Oxford were over the 15% injury threshold, and sprays for pre-tassel to tassel corn were recommended.

Birds, etc.: Flocking species of blackbirds are starting to cause damage in cornfields around the state. Birds may be more of a problem in dry years, when food and water are more difficult to find. 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 APHIS office in Augusta at 1.866.487.3297.

Free disposal of unusable pesticides:  The Maine Board of Pesticides Control (BPC) and the Maine Department of Environmental Protection (DEP) are sponsoring the Obsolete Pesticides Collection Program. This free program is open to homeowners, family-owned farms and greenhouses. Collections of unwanted pesticides will occur at four sites: Presque Isle, Bangor, Augusta, and Portland. Participants must pre-register by September 29, 2017Drop-ins are not permitted. To register, get details, and learn important information about the temporary storage and transportation of obsolete pesticides, go to the Maine BPC web site or call 207.287.2731.

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
Auburn 9 0 15 4-day spray interval recommended on all silking corn
Biddeford 18 0 4-day spray interval recommended on all silking corn
Bowdoinham 0 1 0 No spray recommended
Cape Elizabeth I 14 1 22 0% 4-day spray interval recommended on all silking corn
Cape Elizabeth II 30 0 29 26% 4-day spray interval recommended on all silking corn
Charleston 0 0 0 No spray recommended
Dayton I 0 0 0 0% No spray recommended
Lewiston 1 0 5 One spray for FAW
Garland 2 1 0 6-day spray interval recommended on all silking corn
Levant 0 3 0 7% No spray recommended
Monmouth 2 1 16 6-day spray interval recommended on all silking corn
Nobleboro 1 2 2 No spray recommended
North Berwick 19 0 9 3% 4-day spray interval recommended on all silking corn
Oxford 0 0 11 15% One spray for FAW
Palmyra 0 0 3 0% One spray for FAW
Poland Spring 19 0 19 14% 4-day spray interval recommended on all silking corn
Sabattus 3 3 19 6-day spray interval recommended on all silking corn
Wales 0 0 9 One spray for FAW on all silking corn
Wayne 0 0 2 No spray recommended
Wells 4 2 1 6% 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 IPM
Penn State Sweet Corn IPM
UMass Extension IPM Programs

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: Fall Armyworm on Corn Silk

Image Description: Bird Damage on Corn

Sweet Corn IPM Newsletter No. 10 – August 25, 2017

Sweet Corn IPM Newsletter No. 10 – August 25, 2017
Click on photos to enlarge.

INSECT NUMBERS RISE, INCREASING THREAT

Corn Earworm, Fall Armyworm, European Corn Borer Moth Counts Higher

SITUATION
Fine weather has kept corn development at a good pace, and supply is improving. Quality has been very good in fields where growers have been able to irrigate. Pests that normally emerge later in the season, such as rust and aphids are starting to show up in many fields.

European corn borer:  Moth counts continue to be spotty, with many locations having no moths, but two having counts over the threshold for silking corn. Fields in Wayne and Poland Spring were over the 5-moth threshold for silking corn. Larval feeding injury was still low, but more small larvae are starting to show up in pre-tassel corn.

Corn earworm:  Moth counts were generally higher in most locations this week, calling for a tighter spray schedule for silking corn in most fields, although a few locations had no moths, including Monmouth, Farmington, Oxford, Levant and Palmyra. A 6-day spray interval for corn earworm was recommended for silking fields in Wales and Garland. A 5-day spray schedule was recommended in Bowdoinham, Charleston, Lewiston and one Wells site. A 4-day spray interval was recommended in Auburn, Biddeford, Cape Elizabeth, one Dayton site, Nobleboro, North Berwick, and one Wells site.

Fall armyworm:  Similar to corn earworm, moth counts were mostly higher this week, with many sites over the 3-moth threshold for silking corn. A spray for fall armyworm on silking corn was recommended at one site in Dayton, Monmouth, New Gloucester, Oxford and Sabattus.  Other sites, including Auburn, Biddeford, Cape Elizabeth, Lewiston, Nobleboro, and Wells were also over the 3-moth threshold, but are on a spray schedule for corn earworm. Larval feeding damage in younger corn was lower this week. Fields in Biddeford, and Wells were over the 15% injury threshold, and sprays for pre-tassel to tassel corn were recommended.

Corn leaf aphids have been observed in many fields this week. Colonies of these small, bluish-green insects can cover the tassels, stalks and husks. The aphids excrete a “honeydew” on the leaves and husks, which stimulates the development of sooty mold fungus. This dark, slimy coating greatly reduces the visual appeal of the ears. Sprays applied for corn earworm usually control aphids.

Corn rust:  We have also seen corn rust in many fields this week. Rust is a fungus disease that causes reddish-brown pustules to form on the leaves and husks, reducing the quality of the ears. Typically, corn rust does not become a problem until late in the season. 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®.

Spotted wing drosophila:  Numbers continue to increase in fields with ripe berry fruit. Regular sprays (every 5-7 days) will be needed to prevent raspberries, blueberries and day neutral strawberries from becoming infested with larvae. Visit our Spotted Wing Drosophila blog for more information.

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
Auburn 18 0 21 4-day spray interval recommended on all silking corn
Biddeford 13 1 22 24% 4-day spray interval recommended on all silking corn
Bowdoinham 6 0 2 5-day spray interval recommended on all silking corn
Cape Elizabeth I 28 2 19 6% 4-day spray interval recommended on all silking corn
Cape Elizabeth II 20 3 11 14% 4-day spray interval recommended on all silking corn
Charleston 4 0 2 5-day spray interval recommended on all silking corn
Dayton I 1 0 4 One spray on silking corn for FAW
Dayton II 19 0 12 8% 4-day spray interval recommended on all silking corn
Farmington 0 4 0 No spray recommended
Lewiston 6 0 9 5-day spray interval recommended on all silking corn
Garland 2 0 0 1% 6-day spray interval recommended on all silking corn
Levant 0 0 0 2% No spray recommended
Monmouth 0 0 5 1% One spray on silking corn for FAW
New Gloucester 0 67 5% One spray on silking corn for FAW
Nobleboro 8 0 9 4-day spray interval recommended on all silking corn
North Berwick 32 0 9 0% 4-day spray interval recommended on all silking corn
Oxford 0 0 5 3% One spray on silking corn for FAW
Palmyra 0 0 0 0% No spray recommended
Poland Spring 6 One spray on silking corn for ECB
Sabattus 1 1 3 One spray on silking corn for FAW
Wales 2 0 2 2% 6-day spray interval recommended on all silking corn
Wayne 1 5 0 One spray on silking corn for ECB
Wells I 9 0 3 17% 4-day spray interval recommended on all silking corn
Wells II 6 4 24 8% 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 IPM
Penn State Sweet Corn IPM
UMass Extension IPM Programs

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: Corn Earworm Moth

Image Description: Fall Armyworm Moths

Image Description: Aphids on corn

Image Description: Rust on Corn

Sweet Corn IPM Newsletter No. 9 – August 18, 2017

Sweet Corn IPM Newsletter No. 9 – August 18, 2017
Click on photos to enlarge.

COOL NIGHTS SLOW INSECT ACTIVITY  

Silking Corn Still Needs Protection in Most Fields

SITUATION
Cool nights and dry conditions have slowed corn development, and pushed expected harvests dates back, leading to a short supply of sweet corn in some areas. Expected rain over the weekend and warmer temperatures next week should help the situation. Insect pressure has been somewhat lighter this week, although most fields still require protection for silking corn.

European corn borer:  Moth counts have been spotty around the state.  Most locations continue to see no moths, but counts have increased in a few fields. Fields in North Berwick and Poland Spring were over the 5-moth threshold for silking corn, but both sites are also under a spray interval for corn earworm, so no additional sprays should be needed. Larval feeding injury was low, with most of the injury on late corn due to fall armyworm.

Corn earworm:  Moth counts were generally lower in most locations this week, but still high enough to warrant a tight spray schedule for silking corn in most fields. A 6-day spray interval for corn earworm was recommended for silking fields in Wayne. A 5-day spray schedule was recommended in Bowdoinham, one Cape Elizabeth site, Levant, Poland Spring and one Wells site. A 4-day spray interval was recommended in Auburn, one Cape Elizabeth site, Lewiston, New Gloucester, Nobleboro, North Berwick, Sabattus and one Wells site.

Fall armyworm:  Similar to corn earworm, moth counts were mostly lower this week, although several sites were over the 3-moth threshold for silking corn. A spray for fall armyworm on silking corn was recommended in Biddeford.  Other sites, including Cape Elizabeth, New Gloucester, Nobleboro, Poland Spring, and Wells were also over the 3-moth threshold, but are now on a spray schedule for corn earworm. Larval feeding damage in younger corn was also lower this week. Fields in Auburn, Cape Elizabeth, New Gloucester, Poland Spring and Wells were over the 15% injury threshold, and sprays for pre-tassel to tassel corn were recommended.

Potato leafhopper alert:  We are still seeing signs of potato leafhopper in vegetable and strawberry fields this week. These small, green 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. Controls for potato leafhoppers are listed in the New England Vegetable Management Guide.

Squash vine borer:  Counts were quite low this week, with no fields over the control threshold, which agrees with data from NH. There is the possibility of a second generation emerging over the next few weeks that could threaten late squash and pumpkins or attack ripening fruit.

Spotted wing drosophila: Numbers have been increasing over the past week, and now threaten any soft fruit in the field, such as late raspberries and blueberries. Regular sprays will be needed to prevent such fruit from becoming infested with larvae. Visit our Spotted Wing Drosophila blog for more information.

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
Auburn 18 0 2 47% 4-day spray interval recommended on all silking corn
Biddeford 0 0 3 2% One spray recommended for FAW
Bowdoinham 5 0 2 7% 5-day spray interval recommended on all silking corn
Cape Elizabeth I 6 1 0 20% 5-day spray interval recommended on all silking corn
Cape Elizabeth II 8 9 4-day spray interval recommended on all silking corn
Charleston 1 1 0 No spray recommended
Dayton 5 1 1 1% 5-day spray interval recommended on all silking corn
Farmington 0 0 0 5% No spray recommended
Lewiston 8 1 1 4-day spray interval recommended on all silking corn
Garland 0 2 0 3% No spray recommended
Levant 5 2 3 2% 5-day spray interval recommended on all silking corn
Monmouth 0 0 1 14% No spray recommended
New Gloucester 30 0 28 16% 4-day spray interval recommended on all silking corn
Nobleboro 12 1 3 4-day spray interval recommended on all silking corn
North Berwick 15 5 1 3% 4-day spray interval recommended on all silking corn
Oxford 0 0 1 0% No spray recommended
Palmyra 0 0 1 0% No spray recommended
Poland Spring 6 9 15 20% 5-day spray interval recommended on all silking corn
Sabattus 10 0 0 0% 4-day spray interval recommended on all silking corn
Wales 1 0 0 0% No spray recommended
Wayne 3 0 0 6-day spray interval recommended on all silking corn
Wells I 6 0 2 25% 5-day spray interval recommended on all silking corn
Wells II 9 0 11 5% 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 IPM
Penn State Sweet Corn IPM
UMass Extension IPM Programs

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: Potato Leafhopper

Image Description: Spotted Wing Drosophila Larvae in Blueberry

Sweet Corn IPM Newsletter No. 8 – August 11, 2017

Sweet Corn IPM Newsletter No 8 – August 11, 2017

Click on photos to enlarge.

CORN EARWORM THREAT INCREASES  

Fall Armyworm, European Corn Borer Also Increases

SITUATION
A little bit of rain over most of the state helped move corn along, but cooler weather recently has delayed development of younger fields. Harvest is moving into main season varieties and quality continues to look good. Corn earworm numbers are up significantly in most locations, calling for a tightening of spray intervals.

European corn borer:  Moth counts have increased in some fields this week, suggesting that a second generation of European corn borer may be getting underway in southern Maine, but feeding injury remains low, and most fields are presently being protected with sprays for corn earworm.

Corn earworm:  Moth counts increased significantly in many locations this week, requiring a tightening of spray intervals for silking corn fields. A 6-day spray interval for corn earworm was recommended for silking fields in Monmouth and one Dayton site. A 4-day spray interval was recommended in Auburn, Biddeford, Bowdoinham, one Cape Elizabeth site, one Dayton site, Lewiston, North Berwick, Poland Spring, Wales, and Wells. A 3-day spray interval was recommended at one of the Cape Elizabeth sites.

 Fall armyworm:  Moth counts are still fairly high, and increased at several sites. Most fields are presently under a spray interval for corn earworm, however, so the silking fields should be adequately protected. A spray for fall armyworm on silking corn was recommended in Oxford.  Other sites, including Auburn, Lewiston, Biddeford, Cape Elizabeth, Dayton, Monmouth, New Gloucester, Wales and Wells were also over the 3-moth threshold, but are now on a spray schedule for corn earworm.

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
Auburn 17 0 15 46% 4-day spray interval recommended on all silking corn
Biddeford 36 1 11 6% 4-day spray interval recommended on all silking corn
Bowdoinham 11 0 0 1% 4-day spray interval recommended on all silking corn
Cape Elizabeth I 33 1 15 43% 4-day spray interval recommended on all silking corn
Cape Elizabeth II 118 3 22 38% 3-day spray interval recommended on all silking corn
Charleston 1 1 0 0% No spray recommended
Dayton I 2 0 0 6-day spray interval recommended on all silking corn
Dayton II 37 0 7 11% 4-day spray interval recommended on all silking corn
Farmington 0 0 0 0% No spray recommended
Garland 0 2 0 3% No spray recommended
Levant 5 2 3 2% 5-day spray interval recommended on all silking corn
Lewiston 24 2 9 1% 4-day spray interval recommended on all silking corn
Monmouth 3 0 6 6% 6-day spray interval recommended on all silking corn
New Gloucester 49 One spray recommended for FAW on pre-tassel corn
North Berwick 38 6 2 2% 4-day spray interval recommended on all silking corn
Oxford 1 0 4 0% One spray recommended for FAW
Palmyra 0 0 1 0% No spray recommended
Poland Spring 18 8 2 12% 4-day spray interval recommended on all silking corn
Wales 8 0 6 0% 4-day spray interval recommended on all silking corn
Wells I 8 0 6 31% 4-day spray interval recommended on all silking corn
Wells II 71 0 8 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 IPM
Penn State Sweet Corn IPM
UMass Extension IPM Programs

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 Leaf


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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