Corn earworm update for August 17, 2023

Black light trap captures of corn earworm moths increased this week. Sara Rutherford reported an average of 27 moths per night for Greensville; in Prince George, Scott Reiter had 13 per night (Templeton) and 18 per night (Disputanta); in Suffolk, we saw an average of 62 per night. Here is the updated Table

In our August corn earworm vial tests, 19% of moths survived the 24-hour exposure to 5 micrograms of cypermethrin. This is below our 10-year average of 32% survival.

Corn earworm moth catch has really picked up at some Virginia locations and fall armyworms have appeared in the Northern Neck

There are several corn earworm pheromone traps being monitored around Virginia. Many of the Eastern Shore locations have reported relatively low numbers this week, except for one humongous exception, the Eastern Shore AREC in Painter, VA, where Helene Doughty counted nearly 800 CEW moths in just two nights in one of the traps. That’s the highest density that I’ve ever seen in 20 years. It’s really quite striking because the other traps around Northampton County, VA didn’t catch very many.

Hartstack wire mesh trap baited with pheromone lure with ~790 corn earworm moths. Trap located in Painter, VA. Photo by Helene Doughty.

In Halifax County, Virginia, Mr. Bill Tiver, is still reporting relatively high trap catch at his farm. Catch has ranged from 100 to 250 moths per week. Those numbers would likely suggest that CEW control on susceptible crops like sweet corn, tomato, and beans is a must. Sweet corn spray rotations should probably be 3 times a week under that trap catch level. Meanwhile, in Blacksburg, VA, trap catch has been relatively low so far.

Another pest of sweet corn and some other crops is fall armyworm. According to VCE agent, Stephanie Romelczyk, a sweet corn farm in the Northern Neck of Virginia had a fall armyworm outbreak in the whorls, which required a spray of Coragen. We’re all hoping that it did the trick. So in short, it’s definitely time to monitor for the “worm” pests in your late summer crops.

Fall armyworm larvae. Photo from Bill Tiver.
Fall armyworm in sweet corn. Photo by Tom Kuhar.

Corn Earworm Update – Aug. 10, 2023

The presence of corn ear worm moths in the blacklight traps have increased this week. Sarah Rutherford in Greensville (Jarratt) recorded an average of 13 moths per night; Scott Reiter in Prince George had 62 moths per night in Wells and 42 per night in Rosbicki; The Tidewater AREC entomology team recorded an average of 50 moths per night in Suffolk.

Corn earworm update for Aug. 2, 2023

Corn earworm moth catches are starting to pick up in our black light traps, but at this point are still fairly low. Sara Rutherford in Greensville (Jarratt) averaged 6.8 moths per night; Scott Reiter in Prince George had 3 per night in Templeton and 1.5 per night in Disputanta; the Tidewater AREC entomology team (Benjamin McManaway and Gwenyth Gregory) captured an average of 4.4 moths per night in Suffolk. Here is the Table

Pheromone trap catches of corn earworm moths in Suffolk increased this week–we are using these moths as part of our insecticide resistance monitoring program. So far we have tested 76 moths, with 17.6% surviving a 24-hour exposure to cypermethrin (a pyrethroid insecticide).

Continued Monitoring of Corn Earworm and Armyworm Moth Trap Catch in Virginia – July 27, 2023

INSECT MONITORING PROGRAM – 2023

We are monitoring for corn earworm in multiple Virginia locations this year using the Heliothis (mesh) trap baited with the Hercon pheromone lure.  These moths can damage numerous crops including sweet corn, tomatoes, cotton, soybeans and green beans. Traps of 7 or more moths per week indicate the need for intensive scouting of crops for the pest.

Thank you to all of our trap monitors. 

Northampton County and Eastern Shore AREC – Led by Helene Doughty, Research Specialist Sr. | Entomology, Eastern Shore Agricultural Research and Extension Center

Bill Tiver monitoring in Clover, VA (Halifax County)

Brian Currin (Montgomery County, VA)

Week July 20th – July 27th 2023   Helitothis traps have been set up in 4 locations in Northampton County as well as one location each in Accomack County, Montgomery County, and Halifax County to monitor the activity of the corn earworm moths.  Pheromone bucket traps have also been set up in Northhampton County to monitor the flight activity of the fall armyworm. 

Corn Earworm Trap LocationCEW weekly moth catch 7/27/23Pest pressure
Townsend (Northampton Co.)4Low
Cheriton (Northampton Co.)1Low
Machipongo (Northampton Co.)2Low
Nassawadox (Northampton Co.)2Low
Painter (Accomack Co.)20High
Blacksburg (Montgomery Co.)10Moderate
Clover (Halifax Co.)46High

Fall armyworm trap catch has been low so far, although it’s a little early for that tropical moth. 

Fall Armyworm Trap LocationFAW Count 7/27/23FAW Count 7/20/23
Townsend10
Cheriton00
Machipongo10
Nassawadox00

Be on the Lookout for Early Frogeye Leaf Spot Outbreaks

Within the past week two outbreaks of FLS (frogeye leaf spot) have been reported in southeastern Virginia. Southeastern Virginia has experienced warm, humid conditions and frequent rain events which favor FLS development. Both outbreaks were found on soybean varieties susceptible to FLS in the R1 stage. This creates an issue as the recommendation for fungicide timing on soybeans is R3-R5. Having disease already in the field is also less than ideal as fungicides perform better if applied prior to symptom development. To deal with this situation I recommend:

Scout fields for FLS and Target

  • fields planted to FLS-susceptible varieties and with a history of frogeye leaf spot
  • fields in continuous soybean production
  • fields in short rotations between soybean crops
  • fields with conservation tillage
  • low-lying areas of fields
FLS symptoms found in the upper canopy last Friday.

If you have fields that meet the above risk factors you should use a preventive fungicide application no sooner than R1. If you find FLS in R1 soybeans spray immediately with a FRAC Group 3 (DMI, triazole) fungicide as these fungicides have some curative activity. University pathologists in the U.S. have had the best results with Domark, Topguard, Lucento, Revytek, and Miravis Top when spraying after FLS is detected. Follow-up sprays may be needed if FLS continues to progress.

Corn earworm monitoring in southwest and southside Virginia

Written by Brian Currin (Entomology Graduate Student at Virginia Tech). Brian is working on sweet corn IPM for his research. Corn earworm monitoring is continuing in Virginia. As we grow nearer to the time corn begins to silk, and when corn earworm moths lay their eggs, monitoring is important for integrated pest management strategies.

Trap catch for this week ending July 20 at two locations was as follows:

Clover, VA (Data collected by Bill Tiver) 77 moths per wk (high pressure)
Blacksburg, VA (Data collected by Brian Currin) only 2 moths (very low pressure)

The farm in Blacksburg has yet to reach its reproductive stage but during trap monitoring more adults were seen flying in the corn.

Corn earworm moths caught in a Hartstack wire mesh trap.

Corn earworm trap catch from several locations in Virginia – Week ending July 14, 2023

Mid-July is that time of year when we begin to see corn earworm moth activity really pick up in Virginia.  As most of us know, corn earworm moths deposit their eggs on flowering plants of many important agricultural crops including sweet corn, cotton, soybean, and hemp, to name a few.  Eggs hatch in a couple days into larvae that feed on buds, flowers, fruit, and leaves.  Pheromone trap counts of 7 or more CEW moths per week indicates that this pest is active on the farm and could potentially become a pest threat.   

Corn earworm larva. Helene Doughty photo.

Trap catch for this week ending July 14 at several locations is as follows:

Corn Earworm Trap Locationmoths per wk     
Location6/96/156/226/297/67/13
Townsend46734193
Cheriton122001
Machipongo410021
Nassawadox334010
Chatham   405055
Blacksburg   2108
Corn earworm moth catch in Heliothis mesh traps baited with pheromone lures at 6 locations in Virginia.

In summary, CEW moth activity has subsided on the Eastern Shore for the time being as the pest is likely mostly in the larval stage right now.  In Chatham (southside VA) CEW moth activity has remained high >50 moths per week.  Blacksburg, VA has experienced only low moth numbers so far. 

Thank you to Helene Doughty who is monitoring the traps on the Eastern Shore, Bill Tiver who is monitoring a trap in Clover, VA, and Brian Currin who is monitoring traps around Blacksburg.

The Asian Jumping Worm Invasion: Exploring Its Range and Environmental Consequences in Virginia

This article was written by Jordan Thompson, a graduate student in the Department of Entomology working with Drs. Tom Kuhar and Alejandro Del Pozo. Jordan is a graduate student at Virginia Tech studying the Asian jumping worm in Virginia and hoping to find possible control methods. Jordant95@vt.edu

Earthworms might not be the first thing that comes to mind when thinking about invasive species. In fact, you might be familiar with all the benefits of earthworms, such as how they recycle nutrients by breaking down organic matter, making them more available to plants, or how they tunnel through the soil, aerating it, which in turn makes room for delicate plant roots to spread. You may have even purchased a bag of worm castings to spread in your garden, or perhaps you compost with red wigglers. Whatever your association with earthworms, the thought of eradicating them probably didn’t immediately come to mind.

Unfortunately, we now have a worm in the United States that is detrimental to our delicate soil ecosystems. Known as the Asian jumping worm (Amynthas spp.), this invasive earthworm is named for its signature jumping move, a form of predator evasion. They are characterized by their smooth iridescent skin, and their pale clitellum (band). The Asian jumping worm is able to quickly reshape invaded soil ecosystems, resulting in soil that offers minimal benefits to plants and other terrestrial organisms. Where there was once a rich organic matter layer, is now a dusty and lifeless earth, incapable of supporting certain plant life, thereby permanently altering the landscape and inviting other invasive species to move in and thrive. It is evident that these worms are far from being the allies we seek in maintaining a healthy ecosystem.

But how did they get here? Why does it do so well in so many diverse soils? What are the long-term effects of this species? Let’s break it down.

Figure 1. A graduate student from Virginia Tech holds jumping worms dug from a homeowners property in Floyd, Va, a county previously thought to not have the worm.

The Asian Jumping Worm: An Uninvited Guest

The Asian jumping worm originally hails from East Asia and is believed to have been introduced to other regions through various pathways, including horticultural trade, transportation of plants, and contaminated soil or plant material. One key factor contributing to the Asian jumping worm’s rapid spread is its ability to reproduce via parthenogenesis, meaning it can reproduce without a mate. Each worm produces tiny cocoons at around 60 days of age, and each cocoon will hold between 2 and 20 worms – which will again start producing more cocoons in about 60 days. This allows for about 2 generations per year. Often in a soil rich in organic matter, it is not unusual to find hundreds of worms living within an area of a few square feet. The juveniles are almost microscopic, resembling tiny white threads. The cocoons are the size of a mustard seed, and could easily be picked up by animals and humans walking through worm infested soil.

Additionally, the Asian jumping worm’s adaptability to different soil types is another reason for its success as an invasive species. Although it seems to prefer organic matter rich soils, it can thrive in a wide range of soil conditions, even in sandy or clayey soils. Moreover, unlike other earthworms which tend to stay within certain soil layers, Asian jumping worms are more surface-dwelling, making them highly mobile and able to colonize new areas rapidly.

Their ability to survive in colder climates also contributes to their successful spread. Adults will die with the first frost, but leave behind specialized cocoons that protect their eggs and developing juveniles during winter months. This enables them to establish populations in regions that experience cold winters.

In 2022, Asian jumping worms had been confirmed in a handful of counties in Virginia, but a bit of citizen science with the help of Facebook confirms their presence is being severely under-reported or simply, they’ve been surviving unnoticed, and have likely spread well beyond the original counties.

Disturbing the Ground: Impacts on Soil Ecosystems

Asian jumping worms have a voracious appetite for organic matter. They consume leaf litter, mulch, and other organic debris at an accelerated rate, rapidly depleting the available organic material in the soil. This feeding behavior disrupts the soil structure and leaves soil vulnerable to runoff, in addition to reducing the plant life capable of growing there. This specifically affects forest understories, where small trees and shrubs are essential in providing groundcover, soil stability, and forage for wildlife. When Asian jumping worms invade, it can alter the understory therefore altering the native habitat and displacing wildlife and native plant communities.

In residential areas, avid backyard vegetable growers might notice their gardens becoming less prolific. Their plants might begin to struggle and eventually they may see bare spots where once there were lush gardens. Compost piles can become breeding grounds as banana peels and grass clippings become fuel for more generations of jumping worms. In large turf areas such as golf courses, where worm castings already present an issue with aesthetics and maintenance, worms that altogether destroy the soil could spell disaster for ranges trying to maintain quality greens.

There is some understanding of how these worms alter soil chemistry, C/N (carbon to nitrogen) ratios, and soil electrical conductivity, but more research is needed to better understand the severity of these alterations and their long term effects. What we do know is that while soil development takes thousands of years, the Asian jumping worm can significantly alter soil composition in a matter of months. This poses a grave concern and demands our immediate attention.

Current Research and Areas of Study

Researchers from Virginia Tech’s Department of Entomology are actively studying the impacts of the Asian jumping worm in Virginia and exploring potential control methods. Through field observations and laboratory experiments, they are investigating the effects of Asian jumping worms on other soil arthropods, soil nutrient availability, soil electrical conductivity, and more. By understanding the mechanisms through which these worms degrade the soil, researchers aim to develop targeted management strategies. These may include exploring biological control agents, evaluating cultural practices, and assessing the efficacy of chemical interventions.

Current Research and Areas of Study

Researchers from Virginia Tech’s Department of Entomology are actively studying the impacts of the Asian jumping worm in Virginia and exploring potential control methods. Through field observations and laboratory experiments, they are investigating the effects of Asian jumping worms on other soil arthropods, soil nutrient availability, soil electrical conductivity, and more. By understanding the mechanisms through which these worms degrade the soil, researchers aim to develop targeted management strategies. These may include exploring biological control agents, evaluating cultural practices, and assessing the efficacy of chemical interventions.

Jordan Thompson
Jordant95@vt.edu
BS in Environmental Horticulture VT ‘23
MSLFS in Entomology VT ‘25
Jordan is a graduate student at Virginia Tech studying the Asian jumping worm in Virginia and hoping to find possible control methods.

Join a GROW Farmer Forum on Cover Crop Seeding

GROW will be hosting a Farmer Forum on July 18th, 2023, at 2 p.m. ET. The forum’s presenters will explore everything to do with cover crop seeding, including species selection, cover crop mixes, seed sourcing, seeding rates, seeding methods and timing.

Listen in — and bring your questions — as a panel of farmers from Texas, New York and Delaware discuss their long and varied experience with seeding cover crops! CEU credits will be available.

Speakers:

Registration is FreeSign up here.

Details on how to join the Forum on July 18:

Zoom link: https://virginiatech.zoom.us/j/88338778900?pwd=OUtxRk9zMXoxNEszdFF4UEVKMy84dz09

Meeting ID: 883 3877 8900

Passcode: 150333

Tune into this GROW Farmer Forum to hear experienced farmers share their knowledge on cover crop species, mixes and sourcing as well as seeding rates, methods and timing. (Photo credit: Emily Unglesbee, GROW)