CORN EARWORM REMAINS LOW…  FOR NOW…

Fall Armyworm and European Corn Borer also Remain Scarce

SITUATION
This is a somewhat abbreviated issue, due to the Labor Day holiday and a much reduced scouting team this week.  In addition, it does not include the potential impact of the remains of hurricane Isaac, which are passing over Maine today.  Although insect counts have been very low for this time of year, the passing of a tropical storm can bring with it a significant population of corn pests, especially corn earworm and fall armyworm, so we should anticipate higher pressure by the end of the week for any fresh silking corn remaining in the field.

European corn borer:  Moth counts are very low this week with only one site in Cape Elizabeth exceeding the 5-moth threshold for silking corn, but the site is also on a spray schedule for corn earworm, so no additional sprays are needed.  Feeding damage was also low.  Only a North Berwick field exceeded the 15% threshold when combined with fall armyworm damage.

Corn earworm:  Moth counts were at low to moderate levels this week, although we anticipate increased activity due to the tropical storm remnants passing through Maine today.  A 4-day spray interval for fresh silking corn was recommended for one Dayton location and Nobleboro.  A 5-day spray interval was recommended for Cape Elizabeth, Dayton, New Gloucester, North Berwick,Wayne and Warren.  A 6-day spray interval was recommended for Biddeford, Charleston, Jefferson, Monmouth, Wales and Wells.

Fall armyworm:  Most fields are now in silk and under spray schedules for corn earworm, so very little feeding damage is being noted.  Only one North Berwick field was over the threshold when combined with ECB feeding damage.  Moth captures remain low for this time of year, with no sites exceeding the spray threshold of 3 moths in silking corn.  Single moths were caught in Biddeford, Cape Elizabeth, Monmouth, New Gloucester, and Warren.

The Food Safety Modernization Act (FSMA) and Its Possible Effects on Maine’s Specialty Crop Growers
AgMatters LLC cordially invites you to attend a workshop about this important new legislation.  Joy Johanson from the Produce Safety staff with the FDA will give an overview of FSMA and the Produce Safety Rule.  Representatives from the Maine Board of Pesticides Control will address Worker Protection Training and a new law requiring Pesticide Licensing of all growers.  Lauchlin and Linda Titus from AgMatters LLC will share their impressions on the future of Maine’s Specialty Crop Markets and suggestions on how growers can capitalize on changes in the industry.  Please register for one of the following times and locations:

Tuesday, September 11, 2012
10:00 AM to 2:00 PM
Bangor Motor Inn, 701 Hogan Rd., Bangor (Exit 187 off Interstate 95)
Tel. 207.947.0355

Or

Wednesday, September 12, 2012
10:00 AM to 2:00 PM
Ramada Inn, 490 Pleasant St., Lewiston (Exit 80 off Interstate 95)
Tel. 207.784.2331

Please RSVP as soon as possible by phone 873.2108 or by email to ltitus21@myfairpoint.net.

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

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.

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.

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.

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

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.

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.

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.

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®.

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

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

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.

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.

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.

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

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.

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.

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.

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.

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

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.

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.

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.

Sweet Corn IPM Weekly Scouting Summary

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.

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.

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.

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

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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