Posts Tagged ‘Highmoor Farm’

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

Friday, September 7th, 2018

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

Last Issue for 2018!

MAJOR CORN EARWORM FLIGHT THREATENS LATE CORN

Any Late Silking Fields Remaining Require Tight Spray Interval

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

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

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

Corn Field Plowed Down

Corn Field Plowed Down, photo by David Handley

Oats Cover Crop

Oats Cover Crop, photo by David Handley

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

Corn Earworm Feeding on Corn

Corn Earworm Feeding on Corn, photo by David Handley

Fall Armyworm Eggs on Corn

Fall Armyworm Eggs on Corn, photo by David Handley

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                 UMaine Extension Diagnostic Research Lab
P.O. Box 179                        Pest Management Unit
52 U.S. Route 202              17 Godfrey Drive
Monmouth, ME 04259     Orono, ME 04473
207.933.2100                      1.800.287.0279

 

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
Recommendations / Comments
Biddeford 149 0 26 3-day spray interval recommended on all silking corn
Bowdoinham 1 2 No spray recommended
Cape Elizabeth I 113 0 23 3-day spray interval recommended on all silking corn
Cape Elizabeth II 500+ 121 3-day spray interval recommended on all silking corn
Charleston 15 0 0 4-day spray interval recommended on all silking corn
Corinth 13 0 0 4-day spray interval recommended on all silking corn
Dayton 73 0 19 4-day spray interval recommended on all silking corn
Levant 5 0 4 5-day spray interval recommended on all silking corn
Lewiston 2 0 8 6-day spray interval recommended on all silking corn
Monmouth 15 10 4-day spray interval recommended on all silking corn
New Gloucester 75 41 4-day spray interval recommended on all silking corn
Nobleboro 11 4 4-day spray interval recommended on all silking corn
North Berwick 112 1 3-day spray interval recommended on all silking corn
Oxford 8 96 4-day spray interval recommended on all silking corn
Palmyra 2 1 0 6-day spray interval recommended on all silking corn
Poland Spring 71 6 4-day spray interval recommended on all silking corn
Sabattus 11 1 1 4-day spray interval recommended on all silking corn
Wayne 36 13 4-day spray interval recommended on all silking corn
Wells I 11 0 1 4-day spray interval recommended on all silking corn
Wells II 64 0 38 4-day spray interval recommended on all silking corn

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

Moths caught per week Moths caught per night Spray interval
0.0 to 1.4 0.0 to 0.2 No spray
1.5 to 3.5 0.3 to 0.5 Spray every 6 days
3.6 to 7.0 0.6 to 1.0 Spray every 5 days
7.1 to 91 1.1 to 13.0 Spray every 4 days
More than 91 More than 13 Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

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

Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

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

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

Friday, August 31st, 2018

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

CORN EARWORM, FALL ARMYWORM COUNTS LOWER

Most Silking Fields Still Require Protection

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

Corn Field Plowed Down

Corn Field Plowed Down, photo by David Handley

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

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

Fall Army Worm on Pre-tassel Corn Plant

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

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

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                  UMaine Extension Diagnostic
P.O. Box 179                         Research Lab, Pest Mgmt. Unit
52 U.S. Route 202               17 Godfrey Drive
Monmouth, ME 04259      Orono, ME 04473
207.933.2100                       1.800.287.0279

 

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 7 0 7 4% 5-day spray interval recommended on all silking corn
Bowdoinham 0 0 0 0% No spray recommended
Cape Elizabeth I 19 0 12 4-day spray interval recommended on all silking corn
Cape Elizabeth II 26 2 4 4-day spray interval recommended on all silking corn
Charleston 1 0 0 No spray recommended
Corinth 1 0 1 No spray recommended
Dayton 2 0 1 6-day spray interval recommended on all silking corn
Farmington 1 0 0 No spray recommended
Levant 6 1 1 5-day spray interval recommended on all silking corn
Lewiston I 3 0 0 6-day spray interval recommended on all silking corn
Lewiston II 1 0 0 No spray recommended
Monmouth 13 7 4-day spray interval recommended on all silking corn
New Gloucester 16 0 5 4-day spray interval recommended on all silking corn
Nobleboro 4 0 1 5-day spray interval recommended on all silking corn
North Berwick 5 0 6 0% 5-day spray interval recommended on all silking corn
Oxford 0 0 17 20% Spray recommended for FAW
Palmyra 0 0 0 No spray recommended
Poland Spring 37 0 1 4-day spray interval recommended on all silking corn
Sabattus 9 9 0 4-day spray interval recommended on all silking corn
Wayne 6 0 3 5-day spray interval recommended on all silking corn
Wells I 2 0 0 6-day spray interval recommended on all silking corn
Wells II 4 1 1 5-day spray interval recommended on all silking corn

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

Moths caught per week Moths caught per night Spray interval
0.0 to 1.4 0.0 to 0.2 No spray
1.5 to 3.5 0.3 to 0.5 Spray every 6 days
3.6 to 7.0 0.6 to 1.0 Spray every 5 days
7.1 to 91 1.1 to 13.0 Spray every 4 days
More than 91 More than 13 Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

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

Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

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

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

Monday, August 27th, 2018

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

CORN EARWORM PRESSURE REMAINS HIGH

All Late Silking Corn Requires Protection

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

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

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

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Male Fall Armyworm Moth

Male Fall Armyworm Moth, photo by David Handley

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

Bird Damage on Corn

Bird Damage on Corn, photo by David Handley

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

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      UMaine Extension Diagnostic Research Lab
P.O. Box 179                             Pest Management Unit
52 U.S. Route 202                   17 Godfrey Drive
Monmouth, ME 04259          Orono, ME 04473
207.933.2100                           1.800.287.0279

 

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 12 0 7 3% 4-day spray interval recommended on all silking corn
Bowdoinham 4 0 0 0% 5-day spray interval recommended on all silking corn
Cape Elizabeth I 30 0 37% 4-day spray interval recommended on all silking corn
Cape Elizabeth II 67 29 3 15% 4-day spray interval recommended on all silking corn
Charleston 3 0 0 6-day spray interval recommended on all silking corn
Corinth 12 1 1 4-day spray interval recommended on all silking corn
Dayton 7 0 0 15% 5-day spray interval recommended on all silking corn
Farmington 1 0 0 0% No spray recommended
Levant 4 0 0 5-day spray interval recommended on all silking corn
Lewiston I 15 0 0 4-day spray interval recommended on all silking corn
Lewiston II 2 0 0 6-day spray interval recommended on all silking corn
Monmouth 4 8 4% 5-day spray interval recommended on all silking corn
Nobleboro 11 0 0 4-day spray interval recommended on all silking corn
North Berwick 23 0 0 16% 4-day spray interval recommended on all silking corn
Oxford 13 0 8 20% 4-day spray interval recommended on all silking corn
Palmyra 5 3 0 5-day spray interval recommended on all silking corn
Poland Spring 31 0 4 0% 4-day spray interval recommended on all silking corn
Sabattus 2 5 0 6-day spray interval recommended on all silking corn
Wayne 6 0 4 8% 5-day spray interval recommended on all silking corn
Wells I 7 0 0 5-day spray interval recommended on all silking corn
Wells II 23 2 7 4% 4-day spray interval recommended on all silking corn

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

Moths caught per week Moths caught per night Spray interval
0.0 to 1.4 0.0 to 0.2 No spray
1.5 to 3.5 0.3 to 0.5 Spray every 6 days
3.6 to 7.0 0.6 to 1.0 Spray every 5 days
7.1 to 91 1.1 to 13.0 Spray every 4 days
More than 91 More than 13 Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

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

Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

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

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

Monday, August 20th, 2018

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

FALL ARMYWORM, CORN EARWORM PRESSURE HIGH

Growers Report Difficulty Controlling Fall Armyworm

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

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

Corn Earworm

Corn Earworm, photo by David Handley

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

Fall Armyworm on Corn Leaf

Fall Armyworm on Corn Leaf, photo by David Handley

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

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

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      UMaine Extension Diagnostic Research Lab
P.O. Box 179                             Pest Management Unit
52 U.S. Route 202                   17 Godfrey Drive
Monmouth, ME 04259          Orono, ME 04473
207.933.2100                           1.800.287.0279

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
%Feeding
Damage
Recommendations / Comments
Biddeford 6 6 22 28% 5-day spray interval recommended on all silking corn
Bowdoinham 1 0 0 2% No spray recommended
Cape Elizabeth 9 2 6 3% 4-day spray interval recommended on all silking corn
Charleston 8 0 0 4-day spray interval recommended on all silking corn
Corinth 2 0 8 0% 6-day spray interval recommended on all silking corn
Dayton I 32 6 5 2% 4-day spray interval recommended on all silking corn
Dayton II 15 0 0 8% 4-day spray interval recommended on all silking corn
Farmington 0 3 0 0% No spray recommended
Levant 5 0 2 1% 5-day spray interval recommended on all silking corn
Lewiston I 22 0 2 4-day spray interval recommended on all silking corn
Lewiston II 2 5 0 6-day spray interval recommended on all silking corn
New Gloucester 7 1 9 18% 5-day spray interval recommended on all silking corn
North Berwick 38 0 0 3% 4-day spray interval recommended on all silking corn
Nobleboro 23 2 6 9% 4-day spray interval recommended on all silking corn
Oxford 2 0 6 5% 6-day spray interval recommended on all silking corn
Palmyra 2 2 0 0% 6-day spray interval recommended on all silking corn
Poland Spring 0 0 3 11% One spray for FAW on all silking corn
Sabattus 1 19 0 One spray for ECB on all silking corn
Wayne 9 0 0 4-day spray interval recommended on all silking corn
Wells I 3 0 0 6% 6-day spray interval recommended on all silking corn
Wells II 32 3 5 10% 4-day spray interval recommended on all silking corn

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm

Corn Earworm Spray Thresholds for Pheromone Traps

Moths caught per week Moths caught per night Spray interval
0.0 to 1.4 0.0 to 0.2 No spray
1.5 to 3.5 0.3 to 0.5 Spray every 6 days
3.6 to 7.0 0.6 to 1.0 Spray every 5 days
7.1 to 91 1.1 to 13.0 Spray every 4 days
More than 91 More than 13 Spray every 3 days

Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.

European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.

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

Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

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

 

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.

Strawberry IPM Newsletter No. 6 – July 9, 2018

Monday, July 9th, 2018

StrawberriesStrawberry IPM Newsletter No. 6 – July 9, 2018
Click on photos to enlarge.

RENOVATION AND WEED MANAGEMENT ISSUE

Get Your Strawberry Beds Ready for Next Year

Manage Pests in Day-Neutral Strawberries

A mostly dry spring and warm temperatures led to a somewhat early start, but intense heat as the berries ripened significantly shortened the harvest season for many growers, and may have kept many PYO customers from coming out. A second very dry summer last year also left many beds with thinner plant populations than normal this spring, due to a lack of good runner growth. Pest pressure however, was relatively light in most fields. Spider mites and cyclamen mites were the most common problem across the state. We have seen a lot of Asiatic garden beetles flying around this summer, so growers should be on the lookout for white grub damage, especially in new plantings. (See white grub note below.) Disease pressure was also light in most fields, with leaf spot being the most common problem. A few late rain showers triggered the need for one to three fungicide treatments to keep gray mold to a minimum. Deer and turkeys did some damage to plants over the winter in several fields. All in all, the harvest was good; quantity and quality very good, with berry size down a bit, similar to last year, due to drought during flower bud formation.

Now that harvest is coming to an end, don’t forget about your strawberry plants. Renovation of your beds should begin soon after harvest to allow as much time as possible for the plants to re-establish and form lots of healthy flower buds for next year. Follow the recommended renovation steps listed below for matted row strawberries. Continue to scout for and manage disease, insect and weed problems as they arise. Some of the more common issues to be alert for during the summer are listed below.

DISEASES
Foliar diseases should be monitored in your fields by regularly examining leaves. Foliar diseases are more likely to become apparent under wet weather conditions. The most common summer diseases are powdery mildew, leaf spot and leaf scorch. Fungicides available for these diseases include captan, Topsin-M®, Cabrio®, and Pristine®. See the New England Small Fruit Management Guide for detailed descriptions of these diseases and their management.

Leaf Spot

Leaf Spot, photo by David Handley

Leaf Scorch

Leaf Scorch, photo by David Handley

Black root rot is a disease complex which can be brought on by a combination of factors, including nematodes, soil fungi (Rhizoctonia, Pythium), herbicide carryover, and soil compaction. Plants become weak and may wilt and die. Roots on affected plants are black and poorly developed. This tends to be a problem in fields that have been in strawberries for many seasons, and in fields that have been stressed in other ways, such as winter injury. Rotating fields to crops other than strawberries for at least three years is an important management strategy for black root rot. Improving soil drainage and breaking up hardpans in the soil may also help. Pre-plant root dips with azoxystrobin (Abound®) may also reduce incidence of black root rot.

INSECTS
If black vine weevils or strawberry root weevils are a problem in a strawberry field that you would like to carry over, bifenthrin (Brigade®, Bifenture®) can be applied when adult feeding is noticed (usually until mid-late July). Look for notching along the leaf edges and the presence of the black or brown snout beetles. Applications should be made at night when these insects are active, and the highest rate of the insecticide should be used. For control of the grubs, a soil drench of Platinum® (thiamethoxam) insecticide should be applied during the fall and/or early spring when the grubs are active in the soil. This product has a 50-day pre-harvest interval and may also be used as a pre-plant or planting treatment for root weevils. Parasitic nematodes such as Heterorhabditis bacteriophora or Steinernema feltiae can also be applied to provide control of root weevil grubs in late August. Nematodes require specialized handling and application. Contact us or talk with one of the suppliers for more details. See the New England Small Fruit Management Guide for sources.

Black Vine Weevil

Black Vine Weevil, photo by David Handley

Strawberry Root Weevil Grub

Strawberry Root Weevil Grub, photo by David Handley

White grubs have been a problem in some fields in recent years. The grubs may be the larvae of several species of scarab beetles, including June beetles, rose chafers, Japanese beetles, Asiatic garden beetles and European chafers. The beetles lay their eggs in June and July and the grubs feed on the roots of strawberries from July through mid-September. Affected plants will be stunted and wilted and may die during dry periods. Pulling up plants reveals that roots have been chewed off about an inch below the soil line. Sifting through the soil below the plants may reveal the whitish crescent-shaped grubs which can range in size from 3/8 inch to almost 1 ½ inches long, with six legs near the head and a swollen rear-end. The two most effective periods to treat plantings for grubs are in the spring prior to when they pupate (May) and in the late summer when the next generation is actively feeding (late August). Materials should be applied with plenty of water to moist soil to be sure they reach the root zone. Materials currently registered for control of grubs include Platinum® and Admire Pro®. Parasitic nematodes can also provide control of grubs and should be applied with similar timing. Nematodes are very sensitive to ultraviolet light and dehydration and must be applied with lots of water. See the New England Small Fruit Management Guide for sources of parasitic nematodes.

Strawberry rootworm (not root weevil) is a small (1/8″) dark brown to black beetle that feeds on strawberry foliage, causing it to look skeletonized. The small larvae feed on strawberry roots, further weakening the plant. Adult feeding damage on the leaves usually occurs in the spring and again in late July through August. We did find adults in many fields while we were scouting during bloom this spring. Heavy rootworm feeding weakens strawberry plants so control is warranted when injury is noticed.  Sevin® is registered for control of root worm after harvest.

Strawberry Rootworm Beetle

Strawberry Rootworm Beetle, photo by James Dill

Potato Leafhopper

Potato Leafhopper, photo by James Dill

Keep a lookout for potato leafhoppers; the injury has been common in new strawberry beds this year. The potato leafhopper does not overwinter in Maine, but must fly in from southern states. These small, bullet-shaped insects feed on plant sap from the undersides of leaves, causing the leaves to become curled, stunted and yellow-streaked. Symptoms are often first noticed in new strawberry plantings, and may look like herbicide damage. Leafhoppers will also infest older plantings and a variety of vegetables, flowers and fruit crops. To scout for leafhoppers, brush the leaves of the plants with your hand. The small, whitish adults can be seen flying off the plant. Examine the underside of some injured leaves. Look for small, light green leafhopper nymphs. They are about 1/16 inch long. When touched, they will crawl sideways in a crab-like manner. Controls for potato leafhoppers include Assail®, malathion, carbaryl or Provado®.

MITES
Two-spotted spider mites can increase significantly during the summer, especially in hot, dry weather. Continue to take leaf samples for spider mites throughout the summer. If more than 25% of a 60-leaf sample has mites, controls should be applied. Summer is an ideal time to use predatory mites to control pest mites, because they prefer warm temperatures, and there is less chance of an insecticide spray that might kill them. Amblyseius fallacis can provide good control of two-spotted spider mites when they are released at a rate of about 10,000 mites per acre. Predator mite releases should only be made after a spider mite infestation has been found in the field. Releasing predators into a clean field will often result in them dying, due to a lack of food. See the New England Small Fruit Management Guide for sources of predatory mites.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Cyclamen Mite Damage on Strawberry Plant

Cyclamen Mite Damage on Strawberry Plant, photo by David Handley

Cyclamen mites:  If your field had cyclamen mite symptoms this spring, summer is a good time to control them. After mowing off the leaves, access to the crowns where the mites reside is greatly improved. Plants showing weak growth and yellow, crinkled leaves may be infested with cyclamen mite. These mites are very small and reside down in the crown of the strawberry plant feeding on the developing leaves. They are very hard to see, even with magnification. The miticide Portal® can be effective, but must be applied with lots of water (200 gals.) to be sure that the material is carried down into the crowns.

WEEDS
Weeds often become a big problem during the summer because they are forgotten among all the other demands on our time and because of limited control options. However, the importance of good weed management should not be underestimated.  Keeping weeds under control this summer will help prevent future infestations. Here’s a summary of weed control options for established strawberry beds:

  1. Cultivation: Following renovation, cultivation between strawberry rows can provide effective temporary control of annual weeds. Several types of cultivators are available which will work well in strawberry beds. Cultivators can also be used to help sweep runners into the plant rows.
  1. DCPA (Dacthal®): A pre-emergent herbicide used in the early spring, late fall or after renovation. It offers good short-term control of some annual broadleaf weeds and grasses. It is weak on ragweed, galinsoga, smartweed, shepherd’s purse and mustard. Its action will be improved if worked into the soil by irrigation or light cultivation, and it tends to work best in lighter, warmer soils. This may be used as an alternative to terbacil or napropamide when there is a high risk of plant injury from those products.
  1. Napropamide (Devrinol®): This pre-emergent herbicide provides good control of annual grasses, volunteer grains and some broadleaf weeds. It is typically applied just before mulching in the fall. Split applications have become popular due to the loss of other pre-emergent herbicides, e.g. half maximum rate application after renovation or in late summer after desired daughter plants have rooted, and a second half rate application once the strawberry plants are dormant. Napropamide should be activated by irrigation, rainfall or light cultivation within 24 hours of application. Repeated long-term use of this material, i.e. with no crop rotation, may eventually result in poor daughter plant establishment, due to rooting inhibition.
  1. Terbacil (Sinbar®): An effective pre-emergent herbicide with some post-emergent activity, which should be applied at renovation time – after mowing and tilling the beds, but before new growth begins. A second application can be made in late fall, after the plants are dormant. No more than 6 oz. may be applied in a single application, and no more than 8 oz. may be applied in one season. An example of one season’s use could be 5 oz. applied at renovation and 3 oz. applied in the late fall, the latter in addition to napropamide or DCPA. Terbacil can cause injury to strawberry plants. It is important to determine appropriate rates for each location.
  1. Clopyralid (Spur®): Has both pre-emergent and post emergent activity on many weeds. One application per crop per year following harvest to emerged weeds. Apply uniformly in a minimum of 10 gallons of water per acre. Do not tank mix with other herbicides. Offers control of clover, dandelion and thistle.
  1. Sethoxydim (Poast®): A post-emergent herbicide for control of actively growing grasses. It will not control broadleaf weeds. It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days. Do not use sethoxydim within 6 weeks of terbacil (Sinbar®) applications, to avoid leaf injury. Sethoxydim should be used in combination with a crop oil concentrate. Do not tank mix with 2, 4-D. A second application is often needed for control of perennial grasses.
  1. Clethodim (Arrow®, Prism®, Select®): A post-emergent herbicide, similar in activity to Poast®, for control of actively growing grasses. It will not control broadleaf weeds. It should not be applied when grasses are under stress, e.g. drought, or on unusually hot, humid days. Clethodim should be used in combination with a crop oil concentrate.
  1. Paraquat (Gramoxone Inteon®): A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds. Paraquat will injure or kill strawberries, so applications are made between rows only, with a sprayer shielded to protect the strawberries. It should be used in combination with a nonionic surfactant. Paraquat should not be applied within 21 days of harvest or more than three times in one season.
  1. Pelargonic Acid (Scythe®): A contact herbicide for post-emergent control of most annual weeds and suppression of many perennial weeds. Scythe® will injure or kill strawberries, so applications are made only between rows, with a sprayer shielded to protect the strawberries. This product no residual soil activity. It has a strong, unpleasant odor.
  1. 2,4-D Amine (Formula 40®, Amine 4): A post-emergent herbicide effective on most broadleaf perennial weeds. It will not control grasses, nor offer any pre-emergent control. 2,4-D should be applied immediately after harvest is complete if emerged broadleaf weeds are a problem. After application, the bed should be left undisturbed for three to five days, before mowing the leaves off the plants. This allows time for the material to be taken in by the weeds. This material can also be used when the plants are dormant (late fall or early spring) to control winter annuals and biennials. Fall applications may result in injury to the strawberries if the plants are not completely dormant. Do not tank mix 2,4-D with sethoxydim (Poast®).
  1. Flumloxazin (Chateau®): A pre-emergent herbicide for control of broadleaf weeds, including dandelion and shepherd’s purse. For use in the fall when plants are dormant for control of weeds the following spring.
  1. Pendimethalin (Prowl H20®, Satellite Hydrocap®): A pre-emergent herbicide that may be applied as a band with a shielded sprayer between the rows of strawberries. No weed control will be provided within the plant rows, and contact of this product on the strawberry plants will cause injury. May not be applied within 35 days of harvest. Satellite Hydrocap® may also be applied at renovation, but before new growth begins.

The use of herbicides alone rarely gives complete weed control. Some hand weeding will be necessary. To provide good weed control throughout the life of a strawberry bed, growers should concentrate on crop rotation and good pre-plant weed control.

Strawberry Bed Renovation Review

Bed renovation should begin as soon after harvest as possible. The earlier the beds get renovated, the more time runner plants have to develop, which means larger crowns and more flower buds for next year. Early renovation also improves weed management by tilling in many weeds before they go to seed, and can help with insect, mite and foliar disease control by interfering with life cycles at a critical stage of development. The first step in the bed renovation process is to determine which beds should be carried over for another year and which should be plowed down and put into a crop rotation. Beds that did not suffer much from winter injury, had good production and a good plant stand with no major weed, insect or disease problems should be carried over for another year. Beds that do not meet these criteria should be plowed down and seeded to a suitable cover crop to reduce weed, insect and disease problems that have developed, and to increase soil organic matter content. Ideally, beds that are plowed down should be rotated out of strawberries for at least three years. If properly managed, crop rotation will greatly reduce pest problems and improve the vigor and longevity of strawberry beds without the need for soil fumigation.

Renovating a strawberry bed is basically a thinning process to promote healthy new growth that can support a good crop next spring. While some parts of the following renovation scheme may be modified for individual situations, all beds should undergo the following steps once harvest is complete.

  1. Broadleaf weed control: If perennial broadleaf weeds such as dandelion, shepherd’s purse, daisy or goldenrod are a problem and/or a high population of annual broadleaf weeds such as lambsquarters, sorrel or pigweed are present, hand-pull as many as possible, especially within the plant rows, and/or apply 2,4-D amine (Formula 40®), or clopyralid (Spur®).
Mowing Strawberry Leaves

Mowing Strawberry Leaves, photo by David Handley

  1. Leaf mowing: Four to five days following the 2,4-D application (or immediately if 2,4-D was not applied) mow off the leaves of the strawberries about 1 ½ inches above the crowns. If the planting is weak, it is recommended that this step of the renovation process be skipped.
  1. Fertilization: Apply 40 to 60 pounds of actual nitrogen per acre (use the higher rate on sandy soils and fields where growth has been weak). Phosphorus and potassium applications should be made according to soil test recommendations. Soil testing kits and information are available from your county Cooperative Extension office.
  1. Plant thinning: For the single matted row system, strawberry plant rows should not be any wider than 24 inches. After mowing off the leaves, till the sides of the rows to narrow the beds back to a width of 12 to 18 inches. Use the wider setting for varieties that tend to throw few runners or any fields experiencing drought stress.  Set the tiller so that it incorporates the mowed leaves and spreads about one inch of soil over the remaining crowns at the same time. This will reduce leaf disease and mite problems, and help stimulate new root growth on the remaining plants.
  1. Pre-emergent weed control: To control annual weeds, apply terbacil (Sinbar® 80WP) according to label directions (2 to 6 oz. per acre). Be sure to follow all label precautions. To avoid plant injury, do not use terbacil if you do not intend to mow off the leaves. Napropamide (Devrinol®) or DCPA (Dacthal®) may be used as an alternative to terbacil at this time, as described below. If you are not using herbicides, regular cultivation, before weeds are more than 2” tall, will be needed throughout the summer.
Strawberry Irrigation

Strawberry Irrigation, photo by David Handley

  1. Subsoiling: Soil compaction caused by tractor and picker traffic in the field can cause soil drainage problems and interfere with good root development. Using a subsoiling blade between the rows will break up compacted layers of soil and improve water infiltration. Subsoiling is best done late in the renovation sequence to prevent interference from straw and crop residues.
  1. Irrigation: To encourage rapid plant growth and get the most out of fertilizers and herbicides, irrigate the beds regularly. Strawberries will grow best if they receive 1 ½ inches of water per week during the growing season.

Don’t forget your plants once these renovation steps are completed. Check the strawberry fields regularly during the summer for pest problems. Finding and managing problems early can prevent major problems next spring. Pay close attention to the following items.

NUTRITION
Following the application of 40 to 60 pounds of actual nitrogen at renovation, another 20 pounds of nitrogen should be applied in mid- to late-August to stimulate flower bud development. One way to determine the nutrient status of strawberry plants during the summer is to have a leaf tissue analysis done. Tissue analysis offers a view of what is happening within the plant, and can spot any nutrient deficiencies. In combination with regular soil tests, tissue analysis will provide a complete picture of a field’s fertilizer needs. For more information about tissue analysis contact the Analytical Lab and Maine Soil Testing Service, 5722 Deering Hall, Rm. 407, University of Maine, Orono, Maine 04469-5722, telephone: 207.581.2945.

Pest Management for Day-Neutral Strawberries

Most of the important pests that damage June-bearing varieties can be as much or more of a problem on day-neutral types. Because day-neutral strawberries will have buds, flowers and fruit all occurring at the same time, it is critical to pay close attention to the required number of days to harvest after a pesticide application, to be sure you can safely harvest ripe fruit while still protecting buds and blossoms. Some of the more important pests are listed below, along with currently recommended pesticides and days to harvest as stated on current labels.

Male Spotted Wing Drosophila

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

Spotted wing drosophila (Drosophila suzukii) is a concern for day-neutral strawberries, fall raspberries and blueberries. This is a small fruit fly, similar to those that hover around the bananas in your kitchen. However, this species will lay its eggs on fruit before it ripens, resulting in fruit that is contaminated with small white maggots just as it is ready to pick. Infested fruit quickly rots and has no shelf life. This insect can complete a generation in under two weeks, with each adult female laying hundreds of eggs. Therefore, millions of flies can be present soon after the introduction of just a few into a field. Frequently repeated insecticide sprays (1 to 2 per week) may be needed to prevent infestations once the insect is present in a field. Spotted winged drosophila can successfully overwinter here, although it may not build up to damaging levels until late in the summer. Products that provide good control of drosophila on strawberries include Radiant®, Brigade®, Danitol®, malathion and Assail®. Keeping fields clean of over-ripe and rotten fruit will also help reduce the incidence of this insect. For more information on identifying spotted wing drosophila and updates on populations around the state, visit our Spotted Wing Drosophila blog.

Tarnished plant bug:  This is one of the most prevalent and persistent pests of day-neutral strawberries, because summer flowering coincides with peak populations of this insect. Adult and nymph stages feed on the flowers and developing fruit, causing them to have seedy ends and other malformations. Regular insecticide applications are often required to keep the damage in check. Scout the flower clusters for adults and nymphs often to determine if controls are necessary. Insecticide products for tarnished plant bug include:

Tarnished Plant Bug on Strawberry

Tarnished Plant Bug on Strawberry Flower, photo by David Handley

Tarnished Plant Bug:
Product Days to Harvest
Brigade® 0
Pyganic® 0
Assail® 1
Dibrom® 1
Rimon® 1
Malathion 3

Two-spotted spider mites:  Mites can become a problem during the summer when the growing conditions are warm and dry. In addition to infesting the leaves, mites can move onto the fruit, reducing marketability. Plants that are drought-stressed, over fertilized with nitrogen, or prone to dust covering, e.g. growing beside a dirt road, are especially prone to mite infestation. Predatory mites can be an effective means to control spider mites and keep them in check over the season. Releases should only be made when spider mites are present in the field to provide the predators with a source of food. Most of the products labeled for controlling spider mites will also kill predatory mites; so, do not use these products after predators have been released. Scout for mites often during the season by examining the undersides of the leaves. Control is warranted if more the 25% of leaves examined have mites.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Two-Spotted Spider Mites
Product Days to Harvest
Brigade® 0
Zeal® 1
Vendex® 1
Acramite® 1
Danitol® 2
Agri-Mek® 2
Oberon® 3
Savey® 3
Kelthane® 3

Potato leafhoppers, sap beetles, thrips and spittlebugs may also become problems on day-neutral strawberries, but are less frequently observed than tarnished plant bug and spider mites. Recommendations for these insects can be found in the current edition of the New England Small Fruit Management Guide.

Foliar and fruit diseases also need to be managed on day-neutral strawberries, and should be controlled in much the same way as they are for June-bearing varieties. Most of the fungicide products labeled to control gray mold, powdery mildew, leaf spot and leaf scorch have either zero or one day to harvest, so protecting blossoms at the same time as fruit is near harvest should not be a problem; but be sure to check labels carefully and schedule your sprays and harvests accordingly. Anthracnose fruit rot can be especially troublesome for day-neutral strawberries, because it grows well under warm conditions and spreads by splashing water, which is encouraged on plastic mulch. Fungicides registered for control of anthracnose include Cabrio®, Abound®, Pristine® and Switch®, all of which have zero days to harvest restriction.

Gray Mold on Strawberries

Gray Mold on Strawberries, photo by James Dill

Powdery Mildew

Powdery Mildew, photo by David Handley

Visit the 2017-2018 New England Small Fruit Management Guide online for more detailed pest information.

HOLD THE DATE:

Strawberry Production Workshop
A strawberry workshop will be offered on Thursday January 17, 2019 at the Augusta Civic Center, concurrent with the Maine Agricultural Trades Show, January 15-17, 2019. Details and registration will be available this fall.

Sincerely,

David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm                      Pest Management
P.O. Box 179                             491 College Avenue
Monmouth, ME  04259         Orono, ME  04473
207.933.2100                           1.800.287.0279

Where brand names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against products with similar ingredients. Always consult product label 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.