Corn earworm moth catch data from sweet corn farms in Virginia can be found in the table below. In summary, corn earworm moth activity increased dramatically this week at several locations including lower Northampton County, Westmoreland County in the Northern Neck, Amelia County, Hanover County, and Frederick County.  Moth activity is quite variable right now, and should certainly be monitored carefully in the coming weeks. We still have caught very few fall armyworm moths in our traps around Virginia; however, it should be noted that the Amelia County Farm averaged 5.5 FAW moths per night, which is the highest of any trap this season so far. So, a late flight of this pest appears to have reached some part of Virginia.

In an effort to fend off  pyrethroid insecticide resistance development in our corn earworm populations, rotating to another insecticide than a Class 3 (pyrethroid) is highly encouraged for at least one spray. Diamide insecticides such as Coragen or Besiege (although it includes lambda-cy with the diamide), the carbamate Lannate LV, or the spinosyn Blackhawk, are all effective rotational insecticide options.

I want to once again thank Helene Doughty at the ESAREC and all of the VCE agents that are monitoring these pests on sweet corn farms in 17 different counties in Virginia: Phil Blevins (Washington Co. – See Photograph below); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Roy Flanagan (VA Beach); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.).

Corn earworm moth catch in pheromone-baited Heliothis traps around Virginia for week ending August 24, 2018.

Phil Blevins, Washington County VCE Agent – ANR, standing in front of his Bt sweet corn trial adjacent to a Heliothis trap for corn earworm and a bucket trap for fall armyworm monitoring.

Corn earworm moth catch data from sweet corn farm locations around Virginia can be found in the table below. In summary, corn earworm moth activity has dropped off this week at most locations with the exception of one of the farms in Frederick County where trap catch increased to 13 moths per night. Trap catch remained high at the Creeds location in Virginia Beach with over 20 moths per night being caught, which is high pest pressure still at that location. Moth activity is quite variable right now, and should certainly be monitored carefully in the coming weeks. We have caught very few fall armyworm moths in our traps around Virginia, which is good news. That insect can be quite devastating to late planted sweet corn. Keep an eye on brown marmorated stink bugs feeding on corn ears particularly on field edges (border rows). Fig. 2 below shows BMSB injury to sweet corn from feeding through the husk. Fig. 3 shows the same sweet corn ear after boiling in water. If more than 1 stink bug is found per 10 ears, a pyrethroid insecticide spray is recommended.

Corn earworm trap catch at sweet corn farms in Virginia – week ending August 17, 2018.

Fig. 2. Sweet corn damaged by brown marmorated stink bug.

Fig. 3. Sweet corn ear after being boiled in water. Note the appearance of stink bug feeding on the cooked corn.

Corn earworm moth catch data from sweet corn farm locations around Virginia can be found in the table below.  In summary, corn earworm activity has gone up this week in Accomack County, Virginia Beach, Amelia County, Frederick County, and Franklin County, but has dropped off in many other locations around Virginia.  Thus, moth activity is quite variable right now, but should certainly be monitored carefully in the coming weeks.

Corn earworm pheromone trap catch per night in Virginia.

Insecticide Options for Insect Control in Sweet Corn

Pyrethroids are the most commonly used insecticides in sweet corn.  They are relatively cheap, effective, and include many options such as (alphabetized):
Baythroid XL 1.6 to 2.8 fl oz/A
bifenthrin–2.1 to 6.4 fl oz/A Bifenture 2EC (Sniper, or others);
cyfluthrin–1.6 to 2.8 fl oz/A Tombstone 2EC (or OLF);
esfenvalerate–5.8 to 9.6 fl oz/A Asana XL;
lambda-cyhalothrin–1.28 to 1.92 fl oz/A Warrior II or 2.56 to 3.84 fl oz/A Lambda-Cy (LambdaT) permethrin–4.0 to 8.0 fl oz/A Perm-UP 3.2EC (or OLF)
zeta-cypermethrin–2.8 to 4.0 fl oz/A Mustang Maxx (or OLF)
zeta-cypermethrin+bifenthrin–4.0 to 10.3 fl oz/A Hero EC

Some drawbacks to pyrethroids are that they are broad spectrum contact poisons that are also quite toxic to natural enemies such as ladybeetles and minute pirate bugs, Orius spp., that frequent sweet corn in Virginia and which can destroy many eggs of CEW before the larvae can damage the ears. Pyrethroid insecticides are also toxic to bees.  Frequent use of pyrethroids can also cause outbreaks of corn leaf aphids, which can build up on the ears causing honeydew and sooty mold, which can reduce quality and marketability of the produce.  Corn earworm in Virginia is showing signs of resistance development to pyrethroids and therefore rotating different modes of action is recommended.

Other insecticide classes (different modes of action) that should be considered for use in sweet corn include:

• Lannate LV methomyl –  Will not flare aphids.  HAs not provided as effective control of  corn earworm as the other products when used exclusively.  Is a good rotation or tank mix option.
• Coragen 1.67SC  chlorantraniliprole–3.5 to 5.0 fl oz/A  – this diamide insecticide is virtually non-toxic to bees and natural enemies, and provides excellent control of corn earworm and other worm pests.  Only about two applications can be used per season.  It is an excellent choice during pollen shed.
• Besiege lambda-cyhalothrin+chlorantraniliprole–6.0 to 10.0 fl oz/A  includes both the diamide and a pyrethoid.
• Blackhawk 36WG spinosad–2.2 to 3.3 oz/A or Radiant SC spinetoram–3.0 to 6.0 fl oz/A are spinosysns that provide very good control of corn earworm and other worm pests and are less harmful to many natural enemies.

Corn earworm moth activity has increased in several Virginia locations this week including: Virginia Beach with some traps averaging over 20 moths per night, Hanover County with 16.6 moths per night, and Page County with 10.9 moths per night.  A trap catch exceeding 16 moths per night is quite high and control measures in sweet corn are recommended at short intervals 2-3 days apart (See table below for the trap catch data).

In addition to corn earworm, fall armyworm is another important Lepidopteran “worm” pest that attacks sweet corn.  So far, very few moths have been caught in traps around Virginia, but the some late-planted sweet corn on the Eastern Shore has gotten fall armyworms in the early whorl stage corn, where a lot of damage can occur.  In addition to corn earworm and fall armyworm, the invasive brown marmorated stink bug (BMSB) has occurred in large numbers in some sweet corn fields, including Virginia Beach.  The picture below is from Helene Doughty.  BMSB can feed through the husk and damage multiple kernels, reducing the quality of the produce.  To learn more about BMSB biology, pest threat and management in vegetable crops, click on the following link (pdf) BMSB-in-Vegetables-English

Brown marmorated stink bugs on sweet corn in Virginia Beach. Photo by Helene Doughty (ESAREC).

I’d like to acknowledge the 14 VCE agents that are monitoring moth pests on sweet corn farms in 17 different counties in Virginia: Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.).

Here are some trap catch results (moths per night) for some of the locations around Virginia for this week (note we are missing a lot of data this week from some locations):

Corn earworm moth catch at sweet corn fields in Virginia in 2018

Same trap catch data can be found here:

dataAug2

We’ve seen a jump in corn earworm moth activity this week in many sweet corn fields around Virginia with high levels being reported all around the state, specifically Virginia Beach, Accomack, Northampton, Amelia, Frederick, Page, Montgomery, and Carroll Counties. Fall armyworm moths are also being monitored with bucket traps and very little activity has been observed throughout Virginia.
A catch of >1 or >13 corn earworm moths per night means moderate and high pest pressure, respectively, and a more frequent spray interval is justified.

A big thank you to the 14 VCE agents that are monitoring these pests on sweet corn farms in 17 different counties in Virginia: Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.). Here are some trap catch results (moths per night) for some of the locations around Virginia for this week (note we do not have data for all locations yet):

Corn earworm moth catch in VA for week ending – July 27, 2018.

Moth trap monitoring

We are monitoring corn earworm and fall armyworm moth activity levels on sweet corn farms in 17 different counties in Virginia. Moth Trap Catch Data are being recorded by: Kuhar Vegetable Entomology lab (Montgomery Co.); Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.). Data are posted weekly.

Trap Catch

Below are some trap catch results (moths per night) for some of the locations around Virginia for this week. In summary, we are observing a slight drop off in corn earworm moth activity at most locations, except Amelia County, which posted the highest corn earworm activity this week.  Very little fall armyworm activity has been observed at this point, and numbers are so low that they are not presented.

We are monitoring corn earworm and fall armyworm moth activity levels on sweet corn farms in 17 different counties in Virginia. Moth Trap Catch Data are being recorded by: Kuhar Vegetable Entomology lab (Montgomery Co.); Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.). Data are posted weekly.
Below are some trap catch results (moths per night) for some of the locations around Virginia for this week (note we do not have data for all locations yet).  In summary, we are observing the highest corn earworm activity in the eastern portion of the state including Virginia Beach and Exmore on the Eastern Shore.  Pest pressure is considered high in those locations.  Above threshold trap catch of corn earworm is also being observed on some farms in the southwest region of the state (Franklin County and Montgomery County).  Very little fall armyworm activity has been observed at this point.

Region County        Field                      CEW/night     FAW/night
Eastern Accomack Painter
Eastern Accomack Painter
Eastern Virginia Beach Northridge    3.4                       2.9
Eastern Virginia Beach Pungo            4.3                          0
Eastern Virginia Beach Creeds           5.9                       0.1
Eastern Northampton Capeville         1.0                        0
Eastern Northampton Cheriton          1.9                        0
Eastern Northampton Eastville           0.7                        0
Eastern Northampton Exmore            7.4                        0
Eastern Westmoreland Field                0.2                       0
Central Amelia Field
Central Hanover Wiblin
Central Hanover Haynes
Central Halifax
Central Halifax
Central Charlotte
Northern Loudoun Field1                    1.0                         0
Northern Loudoun Field2                    <.2                        0
Northern Loudoun Field3                    <.2                        0
Northern Rappahannock
Northern Page
Northern Frederick Field1                     0.3                      0
Northern Frederick Field2                     0                         0
Northern Rockingham
Southwest Montgomery Whitethorne   0.0                    0
Southwest Montgomery Homefield       0.0                    0
Southwest Montgomery Wall                  2.0                    0
Southwest Franklin Wirtz                         1.4                    0
Southwest Carroll
Southwest Washington Abingdon

Monitoring sweet corn for pest moth activity can help reduce the number of insecticide applications.  At Kentland Farm in Whitethorne, VA, we recently harvested the first of several tests, where we followed an IPM approach and compared it to sprays of the pyrethroid lambda-cyhalothrin 3 times per week during silking.  We saw no difference in the level of control from an IPM approach- only spraying when needed and spraying the diamide Coragen first compared with the frequent lambda pyrethroid sprays.   We will be harvesting multiple sites for this experiment and will share these when all of the data are in.  Several commercial sweet corn farms are still being monitored around Virginia for corn earworm and fall armyworm.  However, many fields have been harvested already and trapping has been discontinued.  Moth Trap Catch Data are being recorded by:  Katlyn Catron  (Montgomery Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co. & Virginia Beach); Kenner Love (Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk  (Westmoreland Co.); Laura Siegle (Amelia Co.); and Mark Sutphin (Frederick Co.).

This week we observed general drop-off in corn earworm moth catch at many locations, but a big jump in numbers in Rockingham County in the Shenandoah Valley.  Fall armyworm moths never really amounted to anything this year. For corn earworm, moth trap catch of less than 1 per night means  low pest pressure and sweet corn sprays can probably be spaced 5-6 days apart during silking.  However, a catch of >1 or >13 moths per night means moderate and high pest pressure, respectively, and a more frequent spray interval (every 3 or 2 days) is justified.  Here are the trap catch results (moths per night) for several locations around Virginia for this week (note we do not have data for all locations):

Large corn earworm larva in sweet corn soon getting ready to exit the ear to pupate in the ground.

Monitoring sweet corn for pest moth activity can help reduce the number of insecticide applications.  At Kentland Farm in Whitethorne, VA, we recently harvested the first of several tests, where we followed an IPM approach and compared it to sprays of the pyrethroid lambda-cyhalothrin 3 times per week during silking.  We saw no difference in the level of control from an IPM approach- only spraying when needed and spraying the diamide Coragen first compared with the frequent lambda pyrethroid sprays.   We will be harvesting multiple sites for this experiment and will share these when all of the data are in.  Commercial sweet corn farms are being monitored around Virginia for corn earworm and fall armyworm.  Moth Trap Catch Data are being recorded by:  Katlyn Catron  (Montgomery Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co. & Virginia Beach); Kenner Love (Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk  (Westmoreland Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.).

This week we continued to observe moderate (above threshold) corn earworm moth catch at many locations, to warrant continued spraying.  Some of the areas with the highest CEW activity continue to be the Eastern Shore, and Frederick Co.; however, CEW moth catch has increased in Westmoreland, Rockinham, and Hanover Co.   We still have seen few to no fall armyworm moths yet. For corn earworm, moth trap catch of less than 1 per night means  low pest pressure and sweet corn sprays can probably be spaced 5-6 days apart during silking.  However, a catch of >1 or >13 moths per night means moderate and high pest pressure, respectively, and a more frequent spray interval (every 3 or 2 days) is justified.  Here are the trap catch results (moths per night) for several locations around Virginia for this week (note we do not have data for all locations):