Posts Tagged ‘sweet corn’

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

Friday, August 10th, 2018

Sweet CornSweet 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.

Corn Earworm Larvae

Corn Earworm Larvae, photo by David Handley

Fall Armyworm on Corn Silk

Fall Armyworm on Corn Silk, photo by David Handley

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.

Aphids on Corn Tassel

Aphids on Corn Tassel, photo by Kaytlin Woodman

Rust on Corn

Rust on Corn, photo by David Handley

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.

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

Monday, August 6th, 2018

Sweet CornSweet 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.

European Corn Borer Larva

European Corn Borer Larva, photo by David Handley

Corn Earworm Feeding on Corn

Corn Earworm Feeding on Corn, photo by David Handley

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.

Male Spotted Wing Drosophila

Male Spotted Wing Drosophila, photo by Griffin Dill. Actual size: 2-3 mm.

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.

 

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

Friday, July 27th, 2018

Sweet CornSweet 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 in Tassel

European Corn Borer in Tassel, photo by David Handley

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.

Fall Armyworm Injury on Corn Leaves

Fall Armyworm Injury on Corn Leaves, photo by David Handley

Squash Vine Borer Larva

Squash Vine Borer Larva, photo by Jeffrey Hahn, Univ. of Minnesota Extension

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.

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

Friday, July 20th, 2018

Sweet CornSweet 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 Larva

Squash Vine Borer Larva, photo by David Handley

Japanese Beetle

Japanese Beetle, photo by Edwin Remsberg, USDA

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.

Male and Female Spotted Wing Drosophila Flies

Male (left) and Female (right) Spotted Wing Drosophila, photo by Griffin Dill. Actual size: 2-3 mm.

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.

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

Friday, July 13th, 2018

Sweet CornSweet 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.

Two Squash Vine Borer Moths

Two Squash Vine Borer Moths, photo by Jeffrey Hahn, Univ. of Minnesota Extension

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

Potato Leafhopper, photo by James Dill

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.

Cornfield at Highmoor Farm

Cornfield at Highmoor Farm, photo by David Handley

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.

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

Friday, July 6th, 2018

Sweet CornSweet 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 Moth

European Corn Borer Moth, photo by David Handley

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.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Male Fall Armyworm Moth

Male Fall Armyworm Moth, photo by David Handley

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.

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

Friday, June 29th, 2018

Sweet CornSweet 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.

European Corn Borer Moth

European Corn Borer Moth, photo by David Handley

European Corn Borer Damage

European Corn Borer Damage, photo by David Handley

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.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Fall Armyworm Moths

Fall Armyworm Moths (female right, male left), photo by James Dill

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

Northern Corn Leaf Blight, photo by David Handley

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.

European Corn Borer Trap

European Corn Borer Trap, photo by David Handley

Harstack Trap

Harstack Trap, photo by David Handley

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:
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.

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

Friday, September 15th, 2017

Sweet CornSweet 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

Corn Earworm Moth, photo by David Handley

Fall Armyworm Moths

Fall Armyworm Moths (female right, male left), photo by James Dill

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.

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

Monday, September 11th, 2017

Sweet CornSweet 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.

Corn Earworm Feeding on Corn

Corn Earworm Feeding on Corn, photo by David Handley

Fall Army Worm on Pre-tassel Corn Plant

Fall Army Worm on Pre-tassel Corn, photo by David Handley

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?

Unplowed Corn Field

Unplowed Corn Field, photo by David Handley

Oats Cover Crop

Oats Cover Crop, photo by David Handley

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.

 

 

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

Friday, September 1st, 2017

Sweet CornSweet 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.

Fall Armyworm on Corn Silk

Fall Armyworm on Corn Silk, photo by David Handley

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.

Bird Damage on Corn

Bird Damage on Corn, photo by David Handley

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.

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