Posts Tagged ‘pest management’

Sweet Corn IPM Newsletter No. 12 – August 29, 2012

Wednesday, August 29th, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

CORN EARWORM PRESSURE LOWER UNDER COOL NIGHTS

Fall Armyworm and European Corn Borer Numbers Remain Low

SITUATION
Recent relatively cool nights indicate a shift in the weather pattern and have resulted in a dramatic drop in corn earworm captures this week.  However, populations are still high enough to keep all silking fields on a regular spray schedule.  As we approach Labor Day and the season starts to wind down, we have very little pressure from either fall armyworm or European corn borer.  Hot weather predicted for the remainder of the week will push remaining corn maturity along rapidly.  Remnants of hurricane Isaac may visit Maine next week and could bring with it a new flush of earworm and armyworm.

European corn borer:  Moth counts are very low this week with no sites exceeding the 5-moth threshold for silking corn.  Feeding damage was also low, with only the North Berwick site exceeding the 15% threshold when it was combined with fall armyworm damage.

Corn earworm:  Moth counts were significantly lower in all locations this week, but pressure still remains moderate to high for many locations.  A 3-day spray interval for fresh silking corn was recommended only for North Berwick.  A 4-day spray interval was recommended for Biddeford, one Cape Elizabeth location, Dayton, Dresden, East Corinth, Levant, Lewiston, Monmouth, Wales, Wayne and one Wells location.  A 5-day spray interval was recommended for one Cape Elizabeth location, New Gloucester, Nobleboro, Oxford, and one Wells location.  A 6-day spray interval was recommended for Charleston, Jefferson, Palmyra, Poland Spring, and Warren.

Corn Earworm Larvae

Corn Earworm Larvae, photo by David Handley

Fall armyworm:  We continue to find light feeding damage in some fields, but only North Berwick was over the threshold when combined with ECB feeding damage.  Moth captures continue to be very low for this time of year, with no sites exceeding the spray threshold of 3 moths in silking corn.  Two fall armyworm moths were caught at Cape Elizabeth, and one Lewiston location, and single moths were caught in Biddeford, Cape Elizabeth, Dresden, East Corinth, New Gloucester, and Warren.  Fall armyworm feeding damage was found in Biddeford, Cape Elizabeth and New Gloucester, but was below the 15% threshold.  Most remaining fields are silking and under a spray schedule for corn earworm, so field scouting is not necessary.

Fall Armyworm on Corn Silk

Fall Armyworm on Corn Silk, photo by David Handley

Spotted Wing Drosophila Update:
Over the last week spotted wing drosophila numbers have risen significantly. Flies are now at their highest levels of the season.  We have also found drosophila maggots infesting blueberry, raspberry, blackberry, elderberry, grape and peach fruit this week.  For those with late fruit crops still to harvest, protection is necessary to prevent infestation by spotted wing drosophila.  Up to this point weekly applications of an allowed insecticide have been adequate, but reports from the field suggest that more frequent applications may be necessary to keep fruit free from maggots.  Growers in southern states have found that a 3 to 5-day spray schedule was needed to prevent infestation.

Spotted Wing Drosophila Larva in Blueberry

Spotted Wing Drosophila Larvae in Blueberry, photo by David Handley

 

Spotted Wing Drosophila Larvae in Raspberry

Spotted Wing Drosophila Larvae in Raspberry, photo by David Handley

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
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 1 6% 4-day spray interval for all silking corn
Cape Elizabeth I 9 0 2 All silking 4-day spray interval for all silking corn
Cape Elizabeth II 7 0 1 5% 5-day spray interval for all silking corn
Charleston 2 1 0 1% 6-day spray interval for all silking corn
Dayton I 33 0 0 All silking 4-day spray interval for all silking corn
Dayton II 15 0 0 All silking 4-day spray interval for all silking corn
Dresden 32 0 1 All silking 4-day spray interval for all silking corn
East Corinth 16 0 1 0% 4-day spray interval for all silking corn
Jefferson 3 0 0 All silking 6-day spray interval for all silking corn
Levant 11 0 0 2% 4-day spray interval for all silking corn
Lewiston I 47 0 2 All silking 4-day spray interval for all silking corn
Lewiston II 11 1 0 0% 4-day spray interval for all silking corn
Monmouth 40 0 0 All silking 4-day spray interval for all silking corn
New Gloucester 5 0 1 2% 5-day spray interval for all silking corn
Nobleboro 5 0 0 All silking 5-day spray interval for all silking corn
No. Berwick 129 0 0 18% 3-day spray interval for all silking corn
Oxford 5 0 0 All silking 5-day spray interval for all silking corn
Palmyra 2 0 0 All silking 6-day spray interval for all silking corn
Poland Spring 2 0 0 All silking 6-day spray interval for all silking corn
Wales 20 0 0 All silking 4-day spray interval for all silking corn
Warren 2 0 1 All silking 6-day spray interval for all silking corn
Wayne 18 0 0 All silking 4-day spray interval for all silking corn
Wells I 9 0 0 All silking 4-day spray interval for all silking corn
Wells II 6 1 0 All silking 5-day spray interval for 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:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 11 – August 22, 2012

Wednesday, August 22nd, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

CORN EARWORM PRESSURE CONSISTENTLY HIGH ACROSS STATE

Fall Armyworm and ECB Pressure Present, but Remains Low

SITUATION
With continued southerly weather and thunderstorms passing through the state, insect pressure has remained high, mostly due to corn earworm.  At this point, every location is on at least a 4-day spray interval, with some locations on 3-day intervals.  For many growers, the youngest corn has reached the silking stage as the corn season begins to come to a close.  Warm weather will continue to help corn mature rapidly and insect pressure will likely remain relatively high.

European corn borer:  Insect counts have decreased, with only two locations over the 5-moth threshold:  Biddeford and Charleston.  Feeding damage from ECB in whorl to tassel stage corn has been present in all fields scouted, but exceeded the 15% threshold in only two locations (Biddeford and Sabattus) when fall armyworm damage was added to the total.

European Corn Borer Larvae on Ear

European Corn Borer Larva on Ear, photo by David Handley

Corn earworm:  Moth counts remain high in all locations, putting very high pressure on all silking corn.  A 3-day spray interval for fresh silking corn was recommended for Biddeford, one Cape Elizabeth location, Dayton, one Lewiston location, and Sabattus.  A 4-day spray interval was recommended in one Cape Elizabeth location, Charleston, East Corinth, Farmington, Jefferson, Levant, Livermore Falls, Monmouth, New Gloucester, Nobleboro, Oxford, Palmyra, Poland Spring, Wales, Warren, and Wells.  No locations had a moth count low enough for a 5- or 6-day spray interval.

Corn Earworm Feeding on Corn

Corn Earworm Feeding on Corn, photo by David Handley

Fall armyworm:  We continue to find feeding damage in southern fields, but only Biddeford and Sabattus were over the threshold when combined with ECB feeding damage.  Moth captures remain low for this time of year, with only one Cape Elizabeth location exceeding the spray threshold of 3 moths in silking corn; but the field is already under a spray schedule for corn earworm so no additional sprays should be needed.  Two fall armyworm moths were caught at Monmouth and Sabattus, and a single moth was caught in Biddeford, Cape Elizabeth, and one Dayton location this week, below threshold for silking corn.  Fall armyworm feeding damage was also found in Cape Elizabeth, New Gloucester, and North Berwick, but was below the 15% threshold.

Fall Armyworm Injury on Corn Leaves

Fall Armyworm Injury on Corn Leaves, photo by David Handley

Other Pests of Note
Aphids:  Some fields are starting to show infestations of aphids on the tassels, silks and husks.  While their feeding is not usually a significant problem, the presence of aphids and the sooty mold that develops on the husks as a result of their waste (called honeydew) is often objectionable to customers.  Sprays, other than the Bt’s or spinosad products, that are used to control the major corn pests also offer control of aphids as well, including Asana®, Capture®, Warrior® and Lannate®.

Aphids on Corn

Aphids on Corn, photo by Kaytlin Woodman

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

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

Sweet Corn IPM Weekly Scouting Summary

Location CEW
Moths
ECB
Moths
FAW
Moths
% Feeding
Damage
Recommendations / Comments
Biddeford 95 10 1 15% 3-day spray interval for all silking corn
Cape Elizabeth I 162 3 1 All Silk 3-day spray interval for all silking corn
Cape Elizabeth II 85 4 11 6% 4-day spray interval for all silking corn
Charleston 11 5 0 4% 4-day spray interval for all silking corn
Dayton I 118 1 0 All Silk 3-day spray interval for all silking corn
Dayton II 113 0 1 All Silk 3-day spray interval for all silking corn
East Corinth 21 0 0 2% 4-day spray interval for all silking corn
Farmington 14 0 0 All Silk 4-day spray interval for all silking corn
Jefferson 44 0 0 All Silk 4-day spray interval for all silking corn
Levant 54 3 0 6% 4-day spray interval for all silking corn
Lewiston 152 0 0 All Silk 3-day spray interval for all silking corn
Livermore Falls 29 0 0 3% 4-day spray interval for all silking corn
Monmouth 71 0 2 All Silk 4-day spray interval for all silking corn
New Gloucester 30 0 0 9% 4-day spray interval for all silking corn
Nobleboro 20 2 0 1% 4-day spray interval for all silking corn
Oxford 50 0 0 All Silk 4-day spray interval for all silking corn
Palmyra 8 0 0 4% 4-day spray interval for all silking corn
Poland Spring 29 1 0 All Silk 4-day spray interval for all silking corn
Sabattus 145 2 2 16% 3-day spray interval for all silking corn
Wales 16 0 0 3% 4-day spray interval for all silking corn
Warren 83 2 0 All Silk 4-day spray interval for all silking corn
Wells I 50 0 0 All Silk 4-day spray interval for all silking corn
Wells II 89 3 0 All Silk 4-day spray interval for 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:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 10 – August 15, 2012

Wednesday, August 15th, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

HIGHEST CORN EARWORM COUNTS OF THE SEASON

Fall Armyworm Feeding Observed in Southern Maine

SITUATION
Warm weather has pushed corn maturity along rapidly and supplies are picking up.  A steady flow of weather from the south, including some heavy showers in some areas, is keeping corn earworm pressure very high in most fields this week.  Several locations are now on a recommended 3-day spray interval, which we don’t typically see until early fall when tropical storms start moving through Maine.

European corn borer:  A jump in moth counts in southern Maine suggests an emergence of a second generation of corn borer in that area.  High counts continue to be found in more northern locations as well.  These moths pose a risk to any silking corn that is not presently being sprayed for corn earworm.  Wells, Biddeford, Sabattus, Charleston, Levant, Palmyra, and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn was low in most locations, with only Biddeford exceeding the 15% feeding injury threshold.  North Berwick exceeded the threshold when fall armyworm damage was added to the total.

European Corn Borer Entry Hole

European Corn Borer Entry Hole, photo by David Handley

Corn earworm:  Moth counts continue to increase in most locations, putting very high pressure on all silking corn.  A 3-day spray interval for fresh silking corn was recommended for Biddeford, North Berwick, and Wells this week.  A 4-day spray interval was recommended in Cape Elizabeth, Dayton, Dresden, Levant, Lewiston, Monmouth, Palmyra, Poland Spring, Sabattus, and Warren.  A 5-day spray interval was recommended for New Gloucester, East Corinth and Livermore Falls.  A 6-day spray interval was recommended for fields in Charleston and Wales.

Corn Earworm Larvae

Corn Earworm Larvae, photo by David Handley

Fall armyworm:  Moth captures remain low for this time of year, although we have started finding larval feeding damage in some southern fields.  Only one Cape Elizabeth location exceeded the spray threshold of 3 moths in silking corn, but the field is already under a spray schedule for corn earworm so no additional sprays should be needed.  Two fall armyworm moths were caught at Biddeford and our Dayton locations, and a single moth was caught in Dresden this week, below threshold for silking corn.  Fall armyworm feeding damage was found in Biddeford, Dayton, and North Berwick, but was below the 15% threshold.

Fall Armyworm on Corn Leaf

Fall Armyworm on Corn Leaf, photo by David Handley

Other Pests of Note:
Picnic beetles can become a problem during the late summer on silking corn.  These beetles are about ¼ inch long, black with orange spots.  They can often be found on stalks and ears that are infested with European corn borer or fall armyworm, feeding on sap at an entry or exit hole.  They will also feed on the silks and may work their way into the silk channel.  While the damage is usually insignificant, customers dislike finding the insects in their bags.  Sprays to control corn earworm should provide control of these beetles if they are found in your field.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
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 97 25 2 39% 3-day spray interval for all silking corn
Cape Elizabeth I 36 2 0 0% 4-day spray interval for all silking corn
Cape Elizabeth II 70 0 3 0% 4-day spray interval for all silking corn
Charleston 3 12 0 4% 6-day spray interval for all silking corn
Dayton I 16 2 0 6% 4-day spray interval for all silking corn
Dayton II 34 1 2 10% 4-day spray interval for all silking corn
Dresden 14 0 1 5% 4-day spray interval for all silking corn
East Corinth 6 0 0 3% 5-day spray interval for all silking corn
Farmington 0 1 0 3% No spray recommended
Levant 31 11 0 13% 4-day spray interval for all silking corn
Lewiston 11 4 0 2% 4-day spray interval for all silking corn
Livermore Falls 7 0 0 6% 5-day spray interval for all silking corn
Monmouth 8 0 0 6% 4-day spray interval for all silking corn
New Gloucester 6 0 0 0% 5-day spray interval for all silking corn
North Berwick 172 4 0 17% 3-day spray interval for all silking corn
Palmyra 11 6 0 5% 4-day spray interval for all silking corn
Poland Spring 45 1 0 All Silk 4-day spray interval for all silking corn
Sabattus 8 10 0 4% 4-day spray interval for all silking corn
Wales 2 0 0 0% 6-day spray interval for all silking corn
Warren 38 1 0 10% 4-day spray interval for all silking corn
Wells I 107 1 0 All Silk 3-day spray interval for all silking corn
Wells II 92 5 0 All Silk 3-day spray interval for 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:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 9 – August 8, 2012

Thursday, August 9th, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

CORN EARWORM PUTS MOST LOCATIONS ON SPRAY SCHEDULE

Fall Armyworm Pressure Slowly Increasing

SITUATION
Corn harvest is in full swing across most of the state after the warm weekend weather.  Insect pressure has increased, especially from corn earworm with many locations being placed on 4-day spray intervals.  ECB pressure has remained low with the exception of a few northern locations, and fall armyworm appears to be slightly on the rise, but hasn’t exceeded thresholds anywhere.  With the prospect of southerly thunderstorms throughout most of the next week, insect pressure is not expected to decrease.

European corn borer:  Moth counts were still high in a few northern locations this week, requiring protection of silking corn, though only one location wasn’t already protecting against corn earworm.  Counts remained low in most southern fields.  Biddeford, Charleston, Levant, Palmyra, Wells and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn remained low in all locations this week, not exceeding the 15% feeding injury threshold in any locations.

European Corn Borer Larvae on Pre-tassel Stage Corn

European Corn Borer Larvae on Pre-tassel Stage Corn, photo by David Handley

Corn earworm:  Continued pressure from corn earworm has resulted in spray recommendations at all but 3 locations.  A 4-day spray interval was recommended in Biddeford, Cape Elizabeth, Dayton, Dresden, Levant, one Lewiston location, New Gloucester, Nobleboro, North Berwick, Oxford, and Wells.  A 5-day spray interval was recommended for Jefferson, Lewiston, Monmouth, Palmyra, Poland Spring, Sabattus, and Warren.  A 6-day spray interval was recommended for fields in Charleston and Livermore Falls.  Fields in Farmington and Wales caught single moths, which does not warrant a spray.

Corn Earworm

Corn Earworm, photo by David Handley

Fall armyworm:  Moth captures of fall armyworm are increasing.  When scouting, a spray is recommended if feeding injury exceeds 15% of plants in a pre-silking field.  However, larvae may also move into the ears through the silk channel, behaving similarly to corn earworm.  Pheromone trap catches of 3 or more moths per week indicate a spray is needed to protect silking corn, unless it is already under a spray schedule for corn earworm.  Two fall armyworm moths were caught at each Cape Elizabeth location, both Dayton locations, and a single moth was caught at each Wells location this week.  This is below threshold for silking corn.  No feeding damage was found.

Fall Armyworm Eggs on Corn

Fall Armyworm Eggs on Corn, photo by David Handley

Other Pests of Note:
Corn smut is often observed in fields this time of year.  This fungus disease is easily recognized by the large galls which form in the ears, tassels, and on leaves.  The young galls are silvery-white in color.  When the galls mature they rupture into masses of powdery, black spores.  This fungus tends to infect plants with a prior injury, perhaps from cultivation or insect feeding.  Smut usually affects a few plants in a field and is not considered an economically significant problem.  There is no effective fungicide for corn smut.

Smut on Corn

Smut on Corn, photo by David Handley

Sincerely,David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
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
 % ECB
Damage
Recommendations / Comments
 Biddeford  36  11  0  2% 4-day spray interval for all silking corn
 Cape Elizabeth I  50  0  2  0% 4-day spray interval for all silking corn
 Cape Elizabeth II  20  1  2  0% 4-day spray interval for all silking corn
 Charleston  3  11  0  3% 6-day spray interval for all silking corn
 Dayton I  14  0  2  1% 4-day spray interval for all silking corn
 Dayton II  8  0  2  0% 4-day spray interval for all silking corn
 Dresden  9  0  0  2% 4-day spray interval for all silking corn
 East Corinth  0  6  0  0% One spray recommended for ECB on silking corn
 Farmington  1  1  0  2% No spray recommended
 Jefferson  7  1  0  4% 5-day spray interval for all silking corn
 Levant  11  13  0  10% 4-day spray interval for all silking corn
 Lewiston  4  0  0  0% 5-day spray interval for all silking corn
 Lewiston II  9  0  0  8% 4-day spray interval for all silking corn
 Livermore Falls  2  2  0  1% 6-day spray interval for all silking corn
 Monmouth  6  1  0  7% 5-day spray interval for all silking corn
 New Gloucester  26  0  0  1% 4-day spray interval for all silking corn
 Nobleboro  14  3  0  5% 4-day spray interval for all silking corn
 North Berwick  15  3  0  6% 4-day spray interval for all silking corn
 Oxford  10  0  0  4% 4-day spray interval for all silking corn
 Palmyra  4  5  0  6% 5-day spray interval for all silking corn
 Poland Spring  5  0  0  6% 5-day spray interval for all silking corn
 Sabattus  7  0  0  9% 5-day spray interval for all silking corn
 Wales  1  0  0  4% No spray recommended
 Warren  7  0  0  8% 5-day spray interval for all silking corn
 Wells I  40  0  1  7% 4-day spray interval for all silking corn
 Wells II  48  5  1  1% 4-day spray interval for 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:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 8 – August 1, 2012

Wednesday, August 1st, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

CORN EARWORM PRESSURE INCREASES IN SOUTHERN MAINE

European Corn Borer and Fall Armyworm Threat Remains Small

SITUATION
Harvest is still spotty as growers work through the erratic early corn and hope for better uniformity and quality with the main season crop.  Many fields received just enough rain to get a break from irrigation this week.  A little bit of weather coming up from the southeast coast appears to have bumped up local corn earworm populations, so silking corn is likely to need protection, especially in the southern and coastal areas of the state.

European corn borer:  Moth counts were higher in some northern locations this week, requiring protection of silking corn, but remained low in most southern fields.  Charleston, Levant, Palmyra and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn remained low in most locations this week, only exceeding the 15% feeding injury threshold in Cape Elizabeth and Poland Spring.

European Corn Borer Moth

European Corn Borer Moth, photo by David Handley

Corn earworm:  A significant increase in moth activity over the past two nights has increased the number of fields needing to protect any fresh silking corn.  A 4-day spray interval was recommended in one Cape Elizabeth location and North Berwick.  A 5-day spray interval was recommended for Biddeford, a second Cape Elizabeth location, Monmouth and New Gloucester.  A 6-day spray interval was recommended for fields in Lewiston,Warren and Wells.  Fields in Dayton, Jefferson, Palmyra, Poland Spring and Sabattus caught single moths, which does not warrant a spray.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Fall armyworm:  Two fall armyworm moths were caught in one Cape Elizabeth location this week.  This is below threshold for silking corn.  No feeding damage was found.

Spotted wing drosophila update:  The numbers and range of the “Suzuki Fruit Fly” continue to increase around the state.  We have found this small fruit fly in traps in Limington, Buxton, Sanford, New Gloucester, Mechanic Falls, Poland Spring, Wales, Litchfield, Fayette, Thorndike, Warren and Bucksport.  This week also saw the first capture of this fly in a wild blueberry field in Franklin.  Berry growers need to be on the alert for fruit flies and symptoms of premature fruit decay.  Have your pickers keep fields free of overripe fruit.  At this point, insecticide sprays every 5-7 days appears to provide adequate control.  More frequent sprays may become necessary as populations increase.  There is a good fact sheet about the management of spotted wing drosophila on the Penn State Extension website.

Male Spotted Wing Drosophila

Male and Female Spotted Wing Drosophila

Male and Female Spotted Wing Drosophila, image by Alan Kenage, Capital Press

Corn rust causes reddish-brown pustules to form on the leaves, stalks and husks, reducing the visual quality of the ears.  We see more of this problem in wet, humid seasons.  Some varieties are resistant.  Severe infections can reduce ear size, especially if they occur prior to tassel.  A fungicide spray for rust is only recommended if the infection occurs 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 Bravo®, Quilt® and maneb/mancozeb.

Rust on Corn

Rust on Corn, photo by David Handley

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
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 % ECB Damage Recommendations / Comments
 Biddeford  7  3  0  4% 5-day spray interval for all silking corn
 Cape Elizabeth I  11  0  2  0% 4-day spray interval for all silking corn
 Cape Elizabeth II  6  0  0  21% 5-day spray interval for all silking corn
 Charleston  0  9  0  1% One spray recommended for ECB on silking corn
 Dayton I  1  1  0  3% No spray recommended
 Dayton II  1  0  0  1% No spray recommended
 Dresden  0  1  0  5% No spray recommended
 East Corinth  0  20  0  0% One spray recommended for ECB on silking corn
 Farmington  0  0  0  2% No spray recommended
 Jefferson  1  0  0  7% No spray recommended
 Levant  0  8  0  6% One spray recommended for ECB on silking corn
 Lewiston  2  1  0  0% 6-day spray interval for all silking corn
 Lewiston II  2  3  0  9% 6-day spray interval for all silking corn
 Monmouth  6  2  0  7% 5-day spray interval for all silking corn
 New Gloucester  5  0  0  2% 5-day spray interval for all silking corn
 North Berwick  8  0  0  1% 4-day spray interval for all silking corn
 Oxford  0  0  0  8% No spray recommended
 Palmyra  1  6  0  5% One spray recommended for ECB feeding
 Poland Spring  1  3  0  30% One spray recommended for ECB feeding
 Sabattus  1  1  0  8% No spray recommended
 Wales  0  0  0  13% No spray recommended
 Warren  3  0  0  7% 6-day spray interval for all silking corn
 Wells I  3  0  0  0% 6-day spray interval for all silking corn
 Wells II  3  0  0  1% 6-day spray interval for 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:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 7 – July 25, 2012

Wednesday, July 25th, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

CORN PEST ACTIVITY REMAINS LOW IN MOST LOCATIONS

Western Bean Cutworm Found in Maine Corn Fields

SITUATION
Early harvest is getting into full swing and corn quality is looking good, although ear size has been a bit small due to dry conditions in some areas.  Moth counts continue to be very low for this time of year, but nobody is complaining.

European corn borer:  Moth counts were very low in southern locations this week, but some northern sites continue to have enough moths flying to warrant protection of silking corn.  Three sites, Charleston, Levant and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn was also less prevalent this week, only exceeding the 15% feeding injury threshold in Biddeford, Jefferson, Poland Spring and Sabattus.

European Corn Borer in Tassel

European Corn Borer in Tassel, photo by David Handley

Corn earworm:  There was a slight increase in moth activity in a few locations this week.  A 6-day spray interval for fresh silking corn was recommended for fields in Nobleboro, North Berwick, Palmyra, and Poland Spring.  Three locations had only single moths, which don’t warrant a spray.  Most locations had no moths.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Fall armyworm:  No fall armyworm moths were caught this week and no feeding damage was found in the field.

Western bean cutworm:  A new corn pest for Maine?
We set out pheromone traps for western bean cutworm in cornfields this spring, based on reports that this insect is becoming a problem in corn in the upper Midwest and mid-Atlantic regions.  We have caught a few moths in Wells, Cape Elizabeth and New Gloucester over the past couple weeks, and we’re now evaluating what level of risk these present.  The larvae of western bean cutworm will feed on corn plants and move into the ears either through the silk channel or through the husks.  Unlike corn earworm, they are not cannibalistic; so many larvae may be found in a single ear, feeding on the kernels.  The threshold for feeding injury on plants is 8%.  There isn’t an established threshold for moths laying eggs in silking corn yet, but plants that are already on a spray program for corn earworm should also be protected from western bean cutworm.

Spotted wing drosophila update:  We have found this “new” fruit fly in more locations and in higher numbers this week, threatening raspberries, blueberries and any other soft fruit that is available.   We have now caught this fly in traps in Limington, Sanford, New Gloucester, Mechanic Falls, Wales, Litchfield, Fayette, Thorndike, and Warren.  Growers should be on the alert and look for fruit flies on their fruit and symptoms of premature fruit decay.  At this point, keeping fields free of overripe fruit and weekly insecticide sprays appear to be keeping this pest in check.  However more frequent sprays may become necessary as pest populations increase.  There is a good fact sheet on management of spotted wing drosophila on the Penn State Extension website.

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 & Small Fruit Specialist

Highmoor Farm                      PestManagement Office
P.O. Box179                          491 College Ave
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
%ECB
Damage
Recommendations / Comments
 Biddeford  0  0  0  30% One spray recommended for ECB feeding
 Cape Elizabeth I  0  0  0  6% No spray recommended
 Cape Elizabeth II  0  0  0  10% No spray recommended
 Charleston  0  5  0  1% One spray recommended for ECB on silking corn
 Dayton I  0  0  0  0% No spray recommended
 Dayton II  1  0  0  0% No spray recommended
 Dresden  0  0  0  9% No spray recommended
 East Corinth  0  6  0  0% One spray recommended for ECB on silking corn
 Farmington  0  1  0  3% No spray recommended
 Jefferson  0  0  0  19% One spray recommended for ECB feeding
 Levant  0  5  0  5% One spray recommended for ECB on silking corn
 Lewiston  0  0  3% No spray recommended
 Lewiston II  0  0  0  13% No spray recommended
 Livermore Falls  1  0  0  1% No spray recommended
 Monmouth  0  1  0  0% No spray recommended
 New Gloucester  0  0  0  2% No spray recommended
 Nobleboro  2  0  0  0% 6-day spray interval for all silking corn
 North Berwick  2  0  0  0% 6-day spray interval for all silking corn
 Oxford  0  1  0  5% No spray recommended
 Palmyra  2  3  0  3% 6-day spray interval for all silking corn
 Poland Spring  2  0  0  21% 6-day spray interval for all silking corn
 Sabattus  0  0  0  23% One spray recommended for ECB feeding
 Wales  0  0  0  0% No spray recommended
 Warren  0  0  0  0% No spray recommended
 Wells I  1  0  0  0% No spray recommended
 Wells II  0  1  0  6% No spray recommended

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

Corn Earworm Spray Thresholds for Pheromone Traps

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

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

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

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 6 – July 19, 2012

Thursday, July 19th, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

WARM NIGHTS LEAD TO CORN GROWTH, PEST ACTIVITY STILL LOW

Spotted Wing Drosophila Alert

SITUATION
Despite the warmer night temperatures over the weekend, moth counts remain low.  In many places, the warm nights helped the corn grow rapidly, while in other places corn is exhibiting symptoms of dehydration because of the lack of rain.

European corn borer:  Moth counts continue to be very low this week.  Two sites, Levant and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn exceeded the 15% feeding injury threshold in Biddeford, one Cape Elizabeth location, Jefferson, one Lewiston location, Oxford, Poland Spring, Sabattus and one Wells location this week.

 

European Corn Borer on Ear

European Corn Borer on Ear, photo by David Handley

Corn earworm:  No sprays were recommended for corn earworm this week.  Most locations had no moths, and the locations where corn earworm was present only saw a single moth, which doesn’t warrant a spray.

Fall armyworm:  Though we were expecting moth counts to increase after the warmer nights over the weekend, no fall armyworm moths were caught this week and we have not yet seen any sign of larvae feeding.

Spotted Wing Drosophila (SWD) Alert:  This is a new pest which is a concern for raspberries, blueberries, and day-neutral strawberries, as well as many other soft fruits.  This insect is a small fruit fly, similar to the type that fly around the over-ripe bananas in your kitchen.  However, this species will lay its eggs in fruit before it ripens, resulting in fruit that is contaminated with small white maggots just as it is ready to pick.  As a result, the fruit quickly rots and has no shelf life.  This insect recently came into the U.S. from northern Asia, and caused problems with many berry crops up the east coast last year.  It 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.  This makes them very difficult to control, and frequently repeated insecticide sprays (3 to 5 times per week) may be needed to prevent infestations once the insect is present in a field.  Now that spotted wing drosophila has been confirmed in Limington, Mechanic Falls, Springvale, Thorndike, and Warren, growers should be on the alert and look for fruit flies on their fruit and symptoms of premature fruit decay.  Products that provide good control of drosophila on berries include Delegate®, Brigade®, Danitol®, and malathion.  Please check product labels for rates, post-harvest intervals and safety precautions. Keeping the fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect. For information on identifying spotted wing drosophila and making your own monitoring traps, visit the Michigan State University’s Spotted Wing Drosophila.  There is also a good fact sheet on management of spotted wing drosophila on the Penn State Extension website.

Male and Female Spotted Wing Drosophila Flies

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
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
%ECB Damage Recommendations / Comments
 Biddeford  1  0  0  24% One spray recommended for ECB feeding
 Cape Elizabeth I  0  1  0  1% No spray recommended
 Cape Elizabeth II  0  0  0  29% One spray recommended for ECB feeding
 Charleston  0  1  0  0% No spray recommended
 Dayton I  1  0  0  0% No spray recommended
 Dayton II  1  1  0  0% No spray recommended
 Dresden  0  0  0  3% No spray recommended
 East Corinth  0  6  0  2% One spray recommended for ECB on silking corn
 Farmington  1  0  0  6% No spray recommended
 Jefferson  1  1  0  25% One spray recommended for ECB feeding
 Levant  0  5  0  5% One spray recommended for ECB on silking corn
 Lewiston  1  1  0  2% No spray recommended
 Lewiston II  0  2  0  13% No spray recommended
 Livermore Falls  0  0  0  2% No spray recommended
 Monmouth  0  0  0  0% No spray recommended
 New Gloucester  0  0  0  1% No spray recommended
 Nobleboro  0  4  0  4% No spray recommended
 North Berwick  0  0  0  4% No spray recommended
 Oxford  0  0  0  27% One spray recommended for ECB feeding
 Palmyra  0  3  0  1% No spray recommended
 Poland Spring  1  0  0  41% One spray recommended for ECB feeding
 Sabattus  0  0  0  19% One spray recommended for ECB feeding
 Wales  0  0  0  0% No spray recommended
 Warren  0  0  0  7% No spray recommended
 Wells I  1  1  0  18% One spray recommended for ECB feeding
 Wells II  0  0  0  2% No spray recommended

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

Corn Earworm Spray Thresholds for Pheromone Traps

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

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

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

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 5 – July 11, 2012

Wednesday, July 11th, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

COOL NIGHTS KEEP PEST ACTIVITY LOW

First Corn Harvested in Southern Maine this Week

SITUATION
A stretch of warm, dry weather has corn plantings growing well, although cool nights have prevented rapid growth, and appears to have kept moth activity low.  Some very early corn started under row covers was harvested in southern Maine this week, while early fields further north are just coming into silk.

Corn in Silk Stage

Corn in Silk Stage, photo by David Handley

European corn borer:  Moth counts continue to be very low this week.  Two sites, Sabattus and East Corinth were over the threshold of 5 moths in silking corn.  Feeding injury from larvae in whorl to tassel stage corn exceeded the 15% feeding injury threshold in Biddeford, Jefferson, one Lewiston location, Poland Spring, Sabattus and Warren this week.  Many of the larvae are quite large, suggesting that they may be pupating before ear development in later fields, but some smaller larvae are also present, which could move into silking corn as it becomes available.

European Corn Borer in Tassel

European Corn Borer in Tassel, photo by David Handley

Corn earworm:  With few exceptions, moth counts have been very low this week.  A 5-day spray interval on any silking corn was recommended in Nobleboro where four moths were caught this week, and a 6-day spray interval was recommended for silking fields in Dresden. In fields that do not yet have silking corn, earworm is not a threat.

Fall armyworm:  Despite our first fall armyworm captures last week, we caught no moths this week, and have not yet seen any sign of larvae feeding.  When warmer nights prevail, we can expect the moths to become more active and the larvae to threaten all growth stages of corn.

Potato leafhopper alert:  Symptoms of potato leafhopper feeding are becoming apparent in vegetable and strawberry fields this week.  Leafhoppers are small, bullet-shaped insects that feed on plant sap from the undersides of leaves, causing the leaves to become curled, stunted and yellow-streaked.  Beans are quite susceptible to the injury, in addition to 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 crawl sideways in a crab-like manner.  Controls for potato leafhoppers are listed in the New England Vegetable Management Guide.

Potato Leafhopper - Adult & Nymph

Potato Leafhopper – Adult and Nymph, photo by Penn State College of Agricultural Sciences

Squash vine borer moths are being caught in pheromone traps in southern Maine.  The moths lay their eggs at the base of squash or pumpkin plants, and the larvae tunnel into the vines, causing them to wilt and collapse.  Entry holes can often be found near the base of the plant.  Sprays can be applied to control the moths and prevent egg-laying.  Plow down squash plantings as soon as harvest is complete to prevent borers from overwintering in the field.  There is one generation per year.  See the New England Vegetable Management Guide for more details. Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
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 % ECB Damage Recommendations / Comments
Biddeford  1  2  0  69% 1 spray recommended for ECB feeding (no silking corn)
CapeElizabeth I  0  0  0  0% No spray recommended
CapeElizabeth II  0  0  0  4% No spray recommended
Charleston  0  1  0  1% No spray recommended
Dayton I  1  1  0  0% No spray recommended
Dayton II  1  0  0  8% No spray recommended
Dresden  3  2  0  8% 6-day spray interval recommended for all silking corn
East Corinth  0  6  0  0% One spray recommended for ECB on silking corn
Farmington  0  0  0  3% No spray recommended
Jefferson  0  0  0  20% One spray recommended for ECB feeding
Levant  0  0  0  0% No spray recommended
Lewiston  1  0  0  2% No spray recommended
Lewiston II  4  1  0  30% 1 spray recommended for ECB feeding (no silking corn)
Livermore Falls  0  0  0  0% No spray recommended
Monmouth  0  0  0  0% No spray recommended
NewGloucester  0  0  0  1% No spray recommended
Nobleboro  4  0  0  5% 5-day spray interval recommended for all silking corn
North Berwick  0  0  0  13% No spray recommended
Oxford  0  0  0  9% No spray recommended
Palmyra  0  0  0  0% No spray recommended
Poland Spring  2  1  0  44% 6-day spray interval recommended for all silking corn
Sabattus  0  5  0  15% One spray recommended for ECB on silking corn
Wales  0  0  0  0% No spray recommended
Warren  0  0  0  16% One spray recommended for ECB feeding
Wells I  0  1  0  7% No spray recommended
Wells II  0  1  0  2% No spray recommended

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

Corn Earworm Spray Thresholds for Pheromone Traps

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

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

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

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Sweet Corn IPM Newsletter No. 4 – July 6, 2012

Monday, July 9th, 2012

Sweet Corn

For full page print version, please see link at the bottom.  Click on photos to enlarge.

FALL ARMYWORM MOTHS NOW IN MAINE

All Pests in Low Numbers, but Most Silking Corn Needs Protection

SITUATION
Some fields have been hit hard by thunderstorms during the past week while others saw only moderate temperatures and little, if any rain.  The later plantings are looking better than early seeded fields with better uniformity and growth.  Pests have been relatively quiet.  Although we have started to catch a few fall armyworm moths in our traps, we have not yet found any larvae feeding on corn.

European corn borer:  Moth counts were pretty low this week, although several sites were over the threshold of 5 moths in silking corn.  We did find more feeding injury from larvae in whorl and pre-tassel stage corn, with fields scouted in Biddeford, Lewiston, Sabattus and Wells over the recommended spray thresholds.

European Corn Borer Larva

European Corn Borer Larva, photo by David Handley

European Corn Borer Holes

European Corn Borer Holes, photo by David Handley

Corn earworm:  Moth counts remained low this week, and many fields do not have corn in silk, so the moths do not yet pose a significant threat to those fields.  A 6-day spray interval was recommended for silking fields in Cape Elizabeth, Dayton, Dresden, and New Gloucester.

Corn Earworm Moth

Corn Earworm Moth, photo by David Handley

Fall armyworm:  We captured our first fall armyworm moths of the season this week in two southern Maine fields.  However, at these low levels, fall armyworm is not yet a threat.  Fall armyworm moths tend to lay their eggs on the youngest corn available.  When the larvae hatch, they chew large, ragged holes in the leaves, and may bore into developing ears.  This damage is scouted for along with European corn borer injury, and a spray is recommended if the injury exceeds 15% of plants in a pre-silking field.  Larvae may also move into the ears through the silk channel, behaving similarly to corn earworm.  Pheromone trap catches of 3 or more moths per week indicate a spray is needed to protect silking corn, unless it is already under a spray schedule for corn earworm.

Male Fall Armyworm Moth

Male Fall Armyworm Moth, photo by David Handley

Late blight alert for potatoes and tomatoes

Late blight has recently been reported in tomato and potato plantings in coastal and central Maine.  Growers should be on the alert to catch any early symptoms and be ready to apply appropriate control measures.  Typical symptoms will be water-soaked lesions on the leaves with fine, white cottony mycelium on the undersides.  Infections on the stems appear as dark, almost black lesions.

Late Blight on Tomato

Late Blight on Tomato, photo by James Dill

Please report any suspicious symptoms to the Pest Management Office 581.3883 (1.800.287.0279), or email PMO@umext.maine.edu.  The latest control options for late blight on tomatoes are on the University of New Hampshire Extension web site .

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                      Pest Management Office
P.O. Box179                          491 College Ave
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 % ECB Damage Recommendations / Comments
Biddeford  0  5  0  46% 1 spray recommended for ECB feeding (no silking corn)
Cape Elizabeth I  0  1  1  1% No spray recommended
Cape Elizabeth II  2  0  0  0% 6-day spray interval recommended for all silking corn
Charleston  0  0  0  0% No spray recommended
Dayton I  2  1  0  7% 6-day spray interval recommended for all silking corn
Dayton II  3  0  1  6% 6-day spray interval recommended for all silking corn
Dresden  3  2  0  8% 6-day spray interval recommended for all silking corn
East Corinth  0  0  0  1% No spray recommended
Farmington  0  0  0  3% No spray recommended
Jefferson  0  0  0  0% No spray recommended
Levant  0  2  0  0% No spray recommended
Lewiston  4  1  0  30% One spray recommended for ECB feeding (no silking corn)
Lewiston II  1  0  0  2% No spray recommended (no silking corn)
LivermoreFalls  0  2  0  0% No spray recommended
Monmouth  0  0  0  0% No spray recommended
New Gloucester  3  0  0  0% 6-day spray interval recommended for all silking corn
Nobleboro  0  1  0  0% No spray recommended
North Berwick  1  7  0  9% No spray recommended
Oxford  0  0  0  0% No spray recommended
Palmyra  0  2  0  2% No spray recommended
Poland Spring  0  1  0  12% No spray recommended
Sabattus  0  5  0  15% One spray recommended for ECB feeding
Wales  0  0  0  0% No spray recommended
Warren  0  0  0  3% No spray recommended
Wells I  0  1  0  16% One spray recommended for ECB feeding
Wells II  1  0  0  1% No spray recommended

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

Corn Earworm Spray Thresholds for Pheromone Traps

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

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

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

IPM Web Pages:
http://extension.umaine.edu/ipm/
http://www.pestwatch.psu.edu/sweet_corn.htm
http://www.umass.edu/umext/ipm/

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.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the State of Maine and the U.S. Department of Agriculture cooperating.  Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Strawberry IPM Newsletter No. 6 – July 5, 2012

Friday, July 6th, 2012

Strawberries

For full page print version, please see link at the bottom.  Click on photos to enlarge.

RENOVATION AND WEED MANAGEMENT ISSUE

Spotted Wing Drosophila, White Grubs Threaten Berries this Summer

The open winter of 2011-2012 with its lack of snow cover raised fears of winter injury in strawberry beds this spring.  The early warm up also led to a very early bloom and an increased risk of frost injury.  For most growers, however, relatively mild winter temperatures and good mulch cover prevented widespread winter injury, and well-timed irrigation prevented significant frost damage.  It seemed everything was in place for a very early season, when it started to rain, and rain and rain.  This slowed strawberry development considerably and raised concern about preventing fruit rots, such as gray mold (Botrytis) and leather rot (Phytophthora).  Fungicide sprays through the wet period provided good protection in most fields, as gray mold was kept to a minimum in spite of all the moisture.  The harvest season was pushed back to just a few days ahead of normal for most fields, but the crop was not as heavy as the bloom led us to believe, and the season ended up being fairly short.  As fruit ripened we saw some plants showing signs of stress and, depending upon which field we were in, the problems were related to Phytophthora crown rot, winter injury, black root rot, and/or white grubs.

Don’t forget about your strawberries after harvest.  Follow the recommended renovation steps listed below as soon after harvest as possible, and 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.  All of the common leaf diseases were present in fields this spring and we should expect that they will continue to be a problem through the summer.  The most common summer diseases are powdery mildew, leaf spot and leaf scorch.  Fungicides available for these diseases include captan, Topsin-M®, Cabrio®, Pristine® and Abound®.  See the New England Small Fruit Pest Management Guide for detailed descriptions of these diseases and their management.

Leaf Spot on Strawberry Plant

Leaf Spot, photo by David Handley

Black root rot is a disease complex which can be brought on by a combination of problems, 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 constantly for many seasons, and in fields that are under stress 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.  Recent studies suggest that pre-plant root dips with azoxystrobin (Abound®) may also reduce incidence of black root rot in some fields.

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®) 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 Pest Management Guide for sources.

Black Vine Weevil

Black Vine Weevil, photo by David Handley

White grubs have been a problem in many fields this spring/summer.  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®.  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 Pest Management Guide for sources of parasitic nematodes.

White Grub

White Grub, Photo by David Handley

Strawberry rootworm (not root weevil) is a small (1/8″) dark brown to black beetle which 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 late July through August.  Heavy rootworm feeding weakens strawberry plants so control is warranted when injury is noticed.

Strawberry Rootworm Beetle

Keep a lookout for potato leafhoppers, which can weaken strawberry plants and spread disease.  The potato leafhopper does not overwinter inMaine, 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, but 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 malathion, carbaryl or Provado®.

Potato Leafhopper

Potato Leafhopper, photo by New York State Agricultural Experiment Station

hopperburn1

MITES:  Two-spotted spider mites can become problems during the summer.  Continue to take leaf samples for spider mites after renovation.  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 Pest Management Guide for sources of predatory mites.

Two-spotted Spider Mites

Two-spotted Spider Mites, photo by David Handley

Cyclamen mites:  Plants showing weak growth and yellow, crinkled leaves may be infested with cyclamen mite.  Cyclamen 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.  Miticides such as Thionex®, Kelthane® or Portal® can be effective, but must be applied with lots of water to be sure that the material is carried down into the crowns.  If you suspect you have this problem, give us a call.

Cyclamen Mite Damage

Cyclamen Mite Damage on Strawberry Plant, photo by David Handley

WEEDS:  Weeds can become a big problem during the summer because they are often 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 prevent future infestations.  Here’s a summary of weed control options for strawberries:

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.

2.  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.

3.  Napropamide (Devrinol®):  A pre-emergent herbicide which 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.

4.  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.

5.  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 six weeks of a terbacil (Sinbar®) application to avoid leaf injury.  Sethoxydim should be used in combination with a crop oil concentrate.  Do not tank mix with 2, 4-D.

6.  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.

7.  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.

8.  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 between rows only, with a sprayer shielded to protect the strawberries.  This product has a relatively low toxicity and no residual soil activity.  It has a strong, unpleasant odor.

9.  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.  Such applications have been of minimal benefit in northern New England, and sometimes result in injury to the strawberries.  Do not tank mix 2,4-D with sethoxydim (Poast®).

10.  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.

11.  Pendimethalin (Prowl H20®):  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.

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 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 need to 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®).

2.  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.

Mowing Strawberry Leaves

Mowing Strawberry Leaves, photo by David Handley

3.  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.

4.  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.

5.  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.

6.  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.

7.  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.

Strawberry Irrigation

Strawberry Irrigation, photo by David Handley

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:  Analytical Lab, 5722 Deering Hall, Rm. 407, University of Maine, Orono, ME 04469-5722, telephone: 581.2945.

Sidedressed Strawberry Planting

Sidedressed Strawberry Planting, photo by David Handley

 

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.

Spotted wing drosophila (Drosophila suzukii) is a new pest which is likely to be a concern for day neutral strawberries, fall raspberries and blueberries.  This is a small fruit fly, similar to the type that fly around the over-ripe 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.  As a result, the fruit quickly rots and has no shelf life.  This insect recently came into the U.S.from northern Asia, and caused problems with many berry crops up the east coast last year.  It 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.  This makes them very difficult to control, and frequently repeated insecticide sprays (3 to 5 times per week) may be needed to prevent infestations once the insect is present in a field.  It is likely that spotted winged drosophila can successfully overwinter here, although it may not build up to damaging levels until late in the summer.  We have set out monitoring traps for spotted winged drosophila in fruit plantings around the state to determine the activity of this pest in Maine.  However, these traps are unlikely to provide early warning, i.e. when we find them in a trap they are probably already established in the field.  We will be alerting growers when we find them in Maine.  To date (7/5/12) spotted wing drosophila has been confirmed in berry plantings in Connecticutand Massachusetts, so we expect to find it here soon.  Products that provide good control of drosophila on strawberries include Delegate®, Brigade®, Danitol®, and malathion.  Keeping fields clean of over-ripe and rotten fruit can also help reduce the incidence of this insect.  For information on identifying spotted wing drosophila and making your own monitoring traps, visit the Michigan State University’s Spotted Wing Drosophila website.

Male Spotted Wing Drosophila

Tarnished plant bug:  This is one of the most prevalent and persistent pests of day-neutral strawberries, as 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
Product Days to Harvest
Brigade® 0
Pyganic® 0
Assail® 1
Dibrom® 1
Rimon® 1
malathion 3
Thionex® 4
Large Tarnished Plant Bug Nymph

Third Instar Tarnished Plant Bug Nymph, photo by David Handley

 

Tarnished Plant Bug Injury on Strawberries

Tarnished Plant Bug Injury, Photo by David Handley

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

Two-spotted Spider Mites

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 Pest 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 rotcan 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.

Anthracnose on Strawberry

Anthracnose on Strawberry, photo by North Carolina State University

Visit the 2010-2011 New England Small Fruit Pest Management Guide online for more detailed pest information.

Sincerely,

David T. Handley
Vegetable & Small Fruit Specialist

Highmoor Farm                                  PestManagement
P.O. Box179                                      491 College Avenue
Monmouth,ME 04259                        Orono,ME 04473
207.933.2100                                   1.800.287.0279

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