Search Results for: hornet

Bees, Wasps, And Hornets In The Agriculture Workplace

European Hornet

European Hornet Photo by Sal. Mangiafico

The website, Insect Identification.Org has a list of eighty seven Hymenoptera species found in New Jersey. Hymenoptera are ants, bees, wasps, and sawflies. It’s quite amazing that these species have been apart of the evolutionary record for more than 260 million years. Many are predatory species that feed on other insects. And not surprisingly at first glance, several insects have evolved camouflage to look like the stinging biting insects we learn to avoid. There are currently three theories to explain these body shapes and coloring choices. Mimicry, Masquerading, and what I would call ‘Mob Camouflage’ for lack of a better term as the authors of A Hypothesis to Explain Accuracy of Wasp Resemblances’  state.

Mimicry by less aggressive wasps and non-stinging insects like moths is known as Batesian mimicry and Müllerian mimicry. Batesian mimicry is a phenomenon observed by Sir Henry Walter Bates a British Naturalist who studied butterflies in the late 19th century. In Batesian mimicry, non-harmful species known as the mimic have evolved to model the appearance of a species whose potential predators have learned is harmful (venomous sting, biting injury, poisonous) and thus avoid consuming.

Müllerian mimicry is named after German naturalist Fritz Müller and involves two different but similar species purposefully mimicking each other’s appearances and bad taste to confuse predators.

A third hypothesis proposed in the 2016 paper ‘A Hypothesis to Explain Accuracy of Wasp Resemblances’ suggests that non-aggression by wasps towards sisters during hunting is innate and on sight and is a means to confuse or slip by the sight of the selecting agent (the bird) in a crowd.

A good example of these three adaptations on display in 2021 was the emergence of cicada broods and multiple grasshopper broods. These species are food for many Hymenoptera species and when food is abundant bee, wasp and hornet populations soar. This resulted in significant number of calls to extension offices for assistance in identifying similar patterned species. Many callers wanted to know if their hornet encounter was an asian giant hornet (Vespa mandarinia), a new introduction first found in the Pacific Northwest in 2019 that is not known to be present elsewhere in the U.S. at this time.

On another note, it remains to be seen if any of these common predatorory wasp and hornets develop a taste for spotted lanternflies. In their native range, the parasitic wasp Dryinus browni has developed a taste for lanternflies and biologists are studying the logistics of bringing this species to the U.S. The gypsy moth Ooencyrtus kuvanae introduced to the U.S. in 1908 has also been observed to prey on lanternflies.

Another surprising revelation about mimicry in wasp species, is that for some of these common North American species, both prey and predator can change their color banding from yellow and black to red and black as their range changes. Species commonly seen as yellow and black in New Jersey are red and black in Florida and most likely do so to maximize the benefits of mimicry, masquerade, and mob camouflage relative to the abundance of one particular color pattern over another in that ecological niche. As much of the work force in hand harvest agriculture migrates with the crop harvest, workers maybe familiar with the same species venomous sting but associate it with a different color pattern as seen in a different region or country.

Regardless of where in the world we are from, vertebrates like ourselves innately associate these color patterns with avoidance. In human societies, these warning stripes are incorporated into clothing and infrastructure as social cues to both protect the wearer (safety vests) and alert others to safety hazards.

General Body Color Pattens in Stinging and Non-Stinging Bees, Wasps, and Hornets

Green Body and Yellow: Three different types of sweat bees, cuckoo wasp

Red and Black: Red velvet wasp also known as ‘cow killer’ or as ‘red velvet ant’

Yellow and Black: Eastern yellow jacket hornet, southern yellow jacket hornet, common yellow jacket wasp, asian horntail, five-banded thynnid wasp, ichneumon wasp, hyperparasitic wasp, leucospid wasp, bumble bee, pigeon tremex, square head wasp, weevil wasp

Yellow and Brown: Cicada wasp, paper wasp, european hornets, long tailed ichneumon wasp

Black and White: White faced hornets, mason wasp, leaf cutter bee, potter wasp, scoliid wasp

Brown and Black: Great golden digger wasp, honey bee

Have specific questions about these species or want to learn more? Check out the research at the Department of Entomology at Rutgers https://entomology.rutgers.edu/ and faculty and research program focus at https://entomology.rutgers.edu/personnel/faculty.html or find an extension pest specialist at https://entomology.rutgers.edu/personnel/research-extension-staff.html.

Several companies have published wall posters available on the internet of common bees, wasps, and hornets that may be useful in the workplace. These visual aids would be a useful addition to worker bulletin boards in facilities processing the preferred sugar source (vegetable sugars) many of these species feed on throughout the summer.

Concerned about severe reactions to bee, wasp, ant, or hornet stings? Here is an informative article by Merk Manual https://www.merckmanuals.com/home/injuries-and-poisoning/bites-and-stings/bee,-wasp,-hornet,-and-ant-stings?redirectid=12.

The CDC has an employer fact sheet on how to reduce worker exposure to stinging members of the bee, wasp, and hornet families. https://www.cdc.gov/niosh/topics/insects/beeswasphornets.html.

Talk to your occupational health nurse about adding over the counter antihistamines like diphenhydramine, famotidine, and prescription epinephrine to your agriculture workforce first aid kit. Bee venom medical alert necklaces, bracelets and arm bands can be worn by hyper-sensitive workers in the workforce to aid in rapid response if someone is stung and unable to articulate they need medical attention.

Lastly, keep in mind that as climate changes, the seasons become longer, and temperatures are more favorable to yielding higher populations of queens and workers, the time frame to destroy nests when stinging flying insects are hybernating is also changing.

 

Spread the Word: “Killer” Hornet NOT Found in the Northeastern U.S.

By, Michelle Infante-Casella, Agricultural Agent/Professor, RCE of Gloucester Co. and William Bamka, Agricultural Agent/Associate Professor, RCE of Burlington Co.Asian Giant Hornet

Although media reports have triggered panic over the Asian giant hornet (Vespa mandarinia), there are no reports this pest is present anywhere else in North America besides the Pacific Northwest. Rutgers Cooperative Extension, Agriculture and Natural Resource personnel have received inquiries to identify hornets found by the public. In New Jersey, Rutgers Cooperative Extension county offices have not identified any submitted specimens to be the Asian Giant Hornet. The Asian giant hornet has only had confirmed sightings in Washington State and British Columbia, Canada.

“The species has not yet been detected this spring in Washington State or the British Columbia or anywhere else on the West Coast”, said Professor Dina M. Fonseca, director of the Center for Vector Biology in the Department Entomology in the School of Environmental and Biological Sciences at Rutgers–New Brunswick. “We do not know how the species arrived in the United States but it is important to not overreact.”

Washington State University’s information on the Asian giant hornet confirmed the first U.S. sighting of this hornet in the wild. The first two specimens were found in Nanaimo and White Rock, British Columbia, Canada in fall of 2019.
The hornets were reported to be attacking colonies of honeybees in Washington State. The Asian Giant Hornet is known to aggressively attack honeybees and can destroy entire honeybee colonies. Washington State University recently published an extensive fact sheet with identification and guidance for the public. According to the WSU Pest Alert, Asian Giant Hornets are not generally aggressive towards people, but may sting when threatened.

“The Asian giant hornet is unlikely to be present in New Jersey,” Fonseca said. “while citizens in the Pacific Northwest can help detect any emerging hornets this spring, which is critical for its control, the indiscriminate killing of bees, wasps or other hornet lookalikes, would be detrimental because of beneficial roles these insects provide as plant pollinators and predators of agricultural pests.”

An insect that looks similar and can be confused for the Asian giant hornet is the Cicada killer wasp (Sphecius speciosus). They large solitary Asian Giant Hornetwasps found throughout the U.S. and burrow holes in the soil. Even with their large size, dangerous appearance and “dive-bombing” habit, adult Cicada killer wasps rarely come in contact with people and it is rare they will sting. The males of this species will make “dive-bombing” flight patterns, but do not have a stinger and an attack would not result in a sting. The female’s tubular egg-laying structure on the rear end can function as a very weak stinger. Her mild sting is similar to a slight pin scratch and is not considered by most people to be painful. Rutgers Cooperative Extension has more information on the Cicada Killer Wasp and other bees and wasps.

As more information comes out regarding the Asian giant hornet, it is best to pay attention to where this insect has been confirmed and how far it has spread. It is most likely that the Asian giant hornet would first spread and be reported in surrounding areas bordering Washington State and British Columbia, Canada before any reports would occur on the East Coast. Knowing this information may help to calm fears when seeing other hornets and wasps. As always, take precautions and avoid contact with stinging insects. For identification and recommendations contact your local county Rutgers Cooperative Extension office.

European Hornet: The Mysterious Branch Girdler

During the later weeks of summer & early weeks of fall the mysterious removal of bark sections typically found on branches of Birch, Rhododendron, and Lilac can sometimes be observed. These girdled or stripped bark sections are probably being done by European Hornets. These vespids have been reported to potentially have a worse temperament than timber rattle snakes.

River Birch Branch Girdled by European Hornets; Photo by SKRettke of RCE

River Birch branch girdled by European Hornets.
Photo by SK Rettke of RCE

European Hornet actively foraging on bark & sap of Birch branch; SKRettke of RCE

European Hornet actively foraging on bark & sap of Birch branch. Photo by SK Rettke of RCE


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Veg IPM Update 9/12/25

Greetings from the Veg IPM team!

Sweet Corn

Corn is wrapping up very slowly with the cool weather we’re having. Meanwhile, corn earworm (CEW) moth captures are staying high — many locations need 3-day spray intervals (see map). If temperatures get high (>85 degrees F), shorten the spray interval by one day. Rotation is important for avoiding resistance, and there are four IRAC groups that are registered in silking sweet corn: 1 (carbamates), 3 (pyrethroids), 5 (spinosyns), and 28 (diamides). CEW is at least partly resistant to several pyrethroids, so a spray program should not rely solely on pyrethroids, although they can be useful in tank-mixes or as pre-mixed products, such as Besiege or Elevest (Group 28 + Group 3). For detailed information about resistance and potential spray programs, the University of Delaware has an excellent resource on corn earworm management.

Spray intervals based on nightly pheromone moth captures for the southern part of New Jersey. Note that not all locations in the IPM program are currently trapping. This map is based on the following thresholds: 0 moths = 6-7 day schedule, 1 moth = 5 day spray schedule, 2-20 moths = 4 day spray schedule, 20+ moths = 3 day spray schedule.

We’re seeing fall armyworm (FAW) infestations in many locations. Young larvae will cause damage known as “window paning”, in which the top surface of the leaf is eaten away, leaving behind thin, white, membranous-looking scratch marks. As the larvae get bigger, these feeding marks become more ragged (A). The damage can look somewhat similar to European corn borer feeding, but FAW damage will be more severe and will lead down into the whorl. The caterpillars have a dark head capsule with a distinct, inverted Y-shaped suture (B). They can also be identified by four dark dots arranged in a square on their last segments. We use a treatment threshold of 12% fresh feeding damage in pre-tassel corn. Below this level, treatments for FAW are unlikely to pay off and can flare up aphids. For treatment, we recommend using products other than diamides (IRAC Group 28) when treating whorl-stage infestations, as diamides are important to save for silk protection. Effective products include Lannate (Group 1A), Radiant (Group 5), Intrepid (Group 18), Intrepid Edge (5+18), and Avaunt (Group 22). Note that Avaunt can only be used through tassel push.

Fall armyworm damage (A) and larva (B). Note the distinctive suture on the head, which will differentiate FAW from other caterpillar pests of corn. Photos by Amanda Quadrel

We continue to see corn leaf aphids in sweet corn tassels and ears. In high numbers they can reduce pollination or cause honeydew and sooty mold on ears that harm marketability. Broad spectrum insecticides, especially pyrethroids, can flare up aphids by disrupting the natural enemies that typically control them. We have seen several instances where FAW sprays in the vegetative stage may have caused high aphid populations during silking. If you’re seeing a lot of aphids on corn tassels, you can start your CEW spray rotation with Lannate (group 1A), which has some efficacy for aphids. Come back a week later and check ear tips for aphid populations. If they are high, as in the below picture, use a product more targeted for aphids, such as Assail 30SG or 30 SC (group 4A), Transform WG (group 4C), or Sivanto Prime (group 4D). Keep in mind that Transform WG and Sivanto Prime have 7 day PHIs.

Close up of the silks and leaves at the tip of a corn ear with many blue-green aphids clustered on the leaf.

Corn leaf aphids on the tip of an ear. Note blue-green color with dark tail pipes (also called cornicles), legs, and antennae. Picture by Maria Cramer.

Tomatoes

Thrips are starting to slow down as tomatoes are slowing down, but they’re still out there. Thrips management is especially important because of their ability to vector tomato spotted wilt virus (TSWV), a growing problem in New Jersey where we have resistance-breaking strains. There have been many outbreaks of TSWV (in both peppers and tomatoes) throughout south Jersey this season. Scouting and roguing out these plants (see pictures below) while continuing to manage thrips can help contain losses. Additionally, follow best management practices for reducing TSWV risk throughout the season.

For scouting, we consider 1-5 thrips on 10 leaves to be a low count and more than 5 thrips a high count. Other guides suggest a treatment threshold of 3-5 thrips per flower or the presence of stippling damage on fruit. Western flower thrips, the primary vector of TSWV, has resistance to some carbamates (group 1A) and organophosphates (group 1B) as well as pyrethroids (group 3), so few are useful for management. They are also broad-spectrum and hard on natural enemies, potentially flaring up secondary pests like spider mites. The following products have varying efficacy for western flower thrips management:

  • Group 5 insecticides (e.g. Radiant, Entrust) historically have given the best control, but growers have been finding resistance throughout south Jersey. If you have applied Radiant or Entrust and have not gotten good control, your local thrips populations may be resistant. Group 5 insecticides can also only be used twice per season in a planting.
  • Lannate (Group 1A) gives the next best thrips knockdown, but is broad spectrum and is not a part of all growers’ spray programs.
  • Beleaf 50SG (Group 29) can be very effective applied through drip irrigation, but takes a while to decrease thrips populations. It is systemic, making it safer for natural enemies than some other products.
  • Group 28 products with the active ingredient cyantriniliprole (e.g. Minecto Pro, Verimark, Exirel) provided suppression in trials.
  • Movento (Group 23, active ingredient spirotetramat) — provided suppression in trials.
  • Requiem EC (no group, active ingredient Chenopodium extract) — provided suppression in trials.

Many products only suppress thrips, meaning they kill larvae but not adults, or kill only the active life stages (larvae and adults, not the egg or pupal stages). Rotate between active ingredients and try to avoid getting to very high thrips numbers which are more difficult to knock back down.

A) TSWV symptoms on leaves — note curling, yellowing, and browning. B) Symptoms on green fruit — irregular brown blotches and misshapen fruit. C) Symptoms on red fruit — concentric circles. Photos by Maria Cramer.

We’ve seen some fruit damage from caterpillars, and tomato fruitworm (AKA corn earworm), armyworms (beet and yellow striped), and hornworms on plants and fruit. There are no reliable thresholds for determining when to spray for these caterpillar pests, however scouting and consulting the corn earworm pressure map for the state will help give a sense of risk to the crop. When corn earworm pressure indicates a 3 or 4 day spray interval in corn (2-20 moths per night) as is currently the case in much of the state, tomatoes should be scouted weekly for feeding damage. Beet armyworm moth numbers in traps in Salem and Cumberland counties have been low (>5 per night). Pyrethroid resistance is widespread in tomato fruitworm/corn earworm and beet armyworm, so other classes of insecticides should be used if management is needed.

Tomato fruitworm head visible emerging from a hole in a small green tomato.

Tomato fruitworm/corn earworm infesting a green tomato. Photo by Maria Cramer.

We continue to see high spider mites in many plantings. Spider mites tend to be worse in hot, dry conditions, and their populations can dramatically increase following broad-spectrum insecticides, which reduce their natural enemies. The first sign of their presence is often light-colored stippling seen on the top surface of tomato leaves. The mites causing this damage are usually found on the undersides of leaves, though with bad infestations mites will be found on the upper surface as well. When sampling spider mites, check 10 upper leaflets in at least 5 sites per field. The treatment threshold is 2 mites per leaflet on average (one of the individual leaves that makes up the compound tomato leaf). On farms where crop rotation is limited and the same miticides have been used for multiple years we’re seeing some miticide resistance — check whether and application has decreased mite populations, and if it did not work well, do not keep using it. Rotate between miticides and only treat when above threshold. Some products for spider mites in tomatoes include:

  • Nealta (group 25)
  • Oberon (group 23)
  • Portal (group 21A)
  • Agri-Mek (group 6) *7 day PHI
  • Kanemite (group 20B)
  • Acramite (group 20D) *3 day PHI
Tomato leaves with tiny yellow or white dots on visible on the top surface of the leaf.

Spider mite stippling visible when looking at tomato leaves from above. The spider mites are generally found on the undersides of the leaves. Photo by Maria Cramer.

Peppers

In terms of most insect pests, peppers have been looking very good. We have seen aphids, spider mites, and thrips at low levels so far, however it’s important to keep in mind that thrips can transmit TSWV to peppers as well, and so monitoring and staying on top of thrips populations is crucial. As with tomatoes, finding and roguing out infected plants is important as well (see picture below for symptoms on foliage and fruit).

Two pictures: the top picture shows a pepper plant with mottled yellow and green foliage. The bottom picture shows a cherry hot pepper that is green and red with many concentric circles on the skin.

A) TSWV symptoms on pepper foliage — note mottling and cupping of the foliage. B) Symptoms on cherry pepper fruit. Photos by Maria Cramer.

As a reminder, we have found pepper weevils on pepper weevil traps in Gloucester, Cumberland, and Salem Counties this summer. Read more about pepper weevil biology and management here. If you think you may have pepper weevil on your farm or are interested in monitoring, please contact Maria Cramer.

Cole Crops 

We are seeing many different kinds of caterpillars in fall cole crop plantings, including diamondback moth, imported cabbage worm, cabbage looper, cross-striped cabbageworm, and yellow striped armyworm. All cole crop seedlings can tolerate up to 10% infestation for these caterpillar. For heading cole crops between early vegetative and cupping, the treatment threshold is 30%. As heads form, the treatment threshold goes down to just 5% infestation. Sprayable Bt products (IRAC 11A) such as Dipel, Xentari, or Javelin can be effective on young imported cabbage worm, cross-striped cabbageworm, and yellow-striped armyworm caterpillars. Diamondback moth has resistance to many insecticide groups, and pyrethroids (IRAC 3A) and Bt products (IRAC 11A) are not effective for their management. Besides Bt, materials approved for caterpillar control include Entrust/Radiant (IRAC 5), Proclaim (IRAC 6), Torac (IRAC 21A), and Exirel (IRAC 28).  For Bt products and contact insecticides, coverage on the undersides the leaves is essential.

Caterpillar pests of cole crops. A) Diamondback moth — smooth and tapered at each end. B) Imported cabbageworm — fuzzy and not tapered. C) Cabbage looper — characteristic looping behavior. D) Cross-striped cabbage worm — distinctive stripes, usually occurs in groups. Photos A-C by Maria Cramer, photo D from iNaturalist COO.

Downy mildew is showing up in cole crops. This is a disease that develops best around 50-59ºF and our cool night temperatures are making prime conditions for disease development. Downy mildew may appears as light-colored lesions on the top of the leaves and as masses of white spores on the lower surface. Scout at least 25 plants per field (5 plants in 5 locations), checking the undersides for spores. If you have downy mildew, rotate or tank-mix chlorothalonil 6F (FRAC M05) with another product listed in the Mid-Atlantic Veg Guide for downy mildew in cole crops, rotating MOAs. Use overhead irrigation at times of the day when leaves can dry quickly to slow disease progression.

Downy mildew spore masses on the underside of a collard leaf. Photo by Renee Carter.

Pumpkins and Other Cucurbits

Cucurbit downy mildew was first reported on 7/11/25 on cucumbers in central NJ and has been found on cucumbers and cantaloupe at the Snyder Research Farm in Pittstown. Growers should be applying protectants on cucumbers and cantaloupes for cucurbit downy mildew at this time. As of this post, we still haven’t found any instances of the disease on pumpkins, squash, or watermelon. For information on how to build an effective cucurbit down mildew control program, please reference this post by Dr. Andy Wyenandt and consult the Mid-Atlantic Production Guide for additional materials that can be used.

Cucurbit downy mildew symptoms on the upper surface (A) and underside (B) of cucumber leaves and symptoms on cantaloupe (C). Photos by Amanda Quadrel

In pumpkins, we continue to see squash bug eggs and nymphs. Consider treating for squash bug if you see more than one egg mass or group of nymphs per plant (see photos below).

Squash bug eggs (A), newly hatched nymphs (B), and an adult (C). Photos by Amanda Quadrel

Aphid populations remain present in several scouted fields. While not causing direct damage to the fruits, the honeydew produced by aphids can stick to the fruits and attract hornets or promote sooty mold growth, resulting in unsightly fruit. If a colony is found at three or more sites in a ten site sample, growers may wish to apply control measures. There are several options available, such as Assail, Fulfill, PQZ, Sefina, and Beleaf that are labeled for aphids and are safer for bees. If also dealing with heavy mite populations, Minecto Pro can target both pests, but has a higher toxicity to bees.

Melon aphids infesting a pumpkin leaf. Photo by Amanda Quadrel.

Powdery mildew has shown up in most scouted sites. If more than one leaf in a 50 leaf sample is infected, fungicide programs for powdery mildew should be initiated.

Powdery mildew on pumpkin leaf. Photo by Amanda Quadrel.

In many pumpkin fields, disease management has shifted from foliage to fruit — plan to use a high water volume in sprays if a lot of foliage remains so that sprays can contact fruit sufficiently. A preventative diseases management plan based on recommendations from the Mid-Atlantic Production Guide is important for suppressing many of these diseases. If you suspect diseases in your pumpkins (or other cucurbits), reference the “Diagnosing important diseases in Cucurbit crops” guide or send/bring samples to Rutger’s Plant Diagnostic Lab.

As always, please consult the Mid-Atlantic Commercial Vegetable Production Guide for a comprehensive list of materials that are labeled for specific crops and pests. As always, be sure to follow label rates and application instructions.

The Vegetable IPM Program wishes to thank the following Field Technicians, without whom much of the information presented weekly here would not be available.

Southern team: Renee Carter and Kris Szymanski

Northern team: Martina Lavender, Coco Lin, and Cassandra Dougherty

Veg IPM Update 9/5/25

Greetings from the Veg IPM team!

Sweet Corn

Corn earworm (CEW) moth captures are very high — many locations need 3-day spray intervals (see map). If temperatures get high (>85 degrees F), shorten the spray interval by one day. Rotation is important for avoiding resistance, and there are four IRAC groups that are registered in silking sweet corn: 1 (carbamates), 3 (pyrethroids), 5 (spinosyns), and 28 (diamides). CEW is at least partly resistant to several pyrethroids, so a spray program should not rely solely on pyrethroids, although they can be useful in tank-mixes or as pre-mixed products, such as Besiege or Elevest (Group 28 + Group 3). For detailed information about resistance and potential spray programs, the University of Delaware has an excellent resource on corn earworm management.

Spray intervals based on nightly pheromone moth captures for the southern part of New Jersey. Note that not all locations in the IPM program are currently trapping. This map is based on the following thresholds: 0 moths = 6-7 day schedule, 1 moth = 5 day spray schedule, 2-20 moths = 4 day spray schedule, 20+ moths = 3 day spray schedule.

We’re seeing fall armyworm (FAW) infestations in many locations. Young larvae will cause damage known as “window paning”, in which the top surface of the leaf is eaten away, leaving behind thin, white, membranous-looking scratch marks. As the larvae get bigger, these feeding marks become more ragged (A). The damage can look somewhat similar to European corn borer feeding, but FAW damage will be more severe and will lead down into the whorl. The caterpillars have a dark head capsule with a distinct, inverted Y-shaped suture (B). They can also be identified by four dark dots arranged in a square on their last segments. We use a treatment threshold of 12% fresh feeding damage in pre-tassel corn. Below this level, treatments for FAW are unlikely to pay off and can flare up aphids. For treatment, we recommend using products other than diamides (IRAC Group 28) when treating whorl-stage infestations, as diamides are important to save for silk protection. Effective products include Lannate (Group 1A), Radiant (Group 5), Intrepid (Group 18), Intrepid Edge (5+18), and Avaunt (Group 22). Note that Avaunt can only be used through tassel push.

Fall armyworm damage (A) and larva (B). Note the distinctive suture on the head, which will differentiate FAW from other caterpillar pests of corn. Photos by Amanda Quadrel

We continue to see corn leaf aphids in sweet corn tassels and ears. In high numbers they can reduce pollination or cause honeydew and sooty mold on ears that harm marketability. Broad spectrum insecticides, especially pyrethroids, can flare up aphids by disrupting the natural enemies that typically control them. We have seen several instances where FAW sprays in the vegetative stage may have caused high aphid populations during silking. If you’re seeing a lot of aphids on corn tassels, you can start your CEW spray rotation with Lannate (group 1A), which has some efficacy for aphids. Come back a week later and check ear tips for aphid populations. If they are high, as in the below picture, use a product more targeted for aphids, such as Assail 30SG or 30 SC (group 4A), Transform WG (group 4C), or Sivanto Prime (group 4D). Keep in mind that Transform WG and Sivanto Prime have 7 day PHIs.

Close up of the silks and leaves at the tip of a corn ear with many blue-green aphids clustered on the leaf.

Corn leaf aphids on the tip of an ear. Note blue-green color with dark tail pipes (also called cornicles), legs, and antennae. Picture by Maria Cramer.

Tomatoes

Throughout New Jersey we’re continuing to see high thrips counts both in tunnels and in the field.  Thrips management is especially important because of their ability to vector tomato spotted wilt virus (TSWV), a growing problem in New Jersey where we have resistance-breaking strains. There have been many outbreaks of TSWV (in both peppers and tomatoes) throughout south Jersey this season. Scouting and roguing out these plants (see pictures below) while continuing to manage thrips can help contain losses. Additionally, follow best management practices for reducing TSWV risk throughout the season.

For scouting, we consider 1-5 thrips on 10 leaves to be a low count and more than 5 thrips a high count. Other guides suggest a treatment threshold of 3-5 thrips per flower or the presence of stippling damage on fruit. Western flower thrips, the primary vector of TSWV, has resistance to some carbamates (group 1A) and organophosphates (group 1B) as well as pyrethroids (group 3), so few are useful for management. They are also broad-spectrum and hard on natural enemies, potentially flaring up secondary pests like spider mites. The following products have varying efficacy for western flower thrips management:

  • Group 5 insecticides (e.g. Radiant, Entrust) historically have given the best control, but growers have been finding resistance throughout south Jersey. If you have applied Radiant or Entrust and have not gotten good control, your local thrips populations may be resistant. Group 5 insecticides can also only be used twice per season in a planting.
  • Lannate (Group 1A) gives the next best thrips knockdown, but is broad spectrum and is not a part of all growers’ spray programs.
  • Beleaf 50SG (Group 29) can be very effective applied through drip irrigation, but takes a while to decrease thrips populations. It is systemic, making it safer for natural enemies than some other products.
  • Group 28 products with the active ingredient cyantriniliprole (e.g. Minecto Pro, Verimark, Exirel) provided suppression in trials.
  • Movento (Group 23, active ingredient spirotetramat) — provided suppression in trials.
  • Requiem EC (no group, active ingredient Chenopodium extract) — provided suppression in trials.

Many products only suppress thrips, meaning they kill larvae but not adults, or kill only the active life stages (larvae and adults, not the egg or pupal stages). Rotate between active ingredients and try to avoid getting to very high thrips numbers which are more difficult to knock back down.

A) TSWV symptoms on leaves — note curling, yellowing, and browning. B) Symptoms on green fruit — irregular brown blotches and misshapen fruit. C) Symptoms on red fruit — concentric circles. Photos by Maria Cramer.

We’ve seen some fruit damage from caterpillars, and tomato fruitworm (AKA corn earworm), armyworms (beet and yellow striped), and hornworms on plants and fruit. There are no reliable thresholds for determining when to spray for these caterpillar pests, however scouting and consulting the corn earworm pressure map for the state will help give a sense of risk to the crop. When corn earworm pressure indicates a 3 or 4 day spray interval in corn (2-20 moths per night) as is currently the case in much of the state, tomatoes should be scouted weekly for feeding damage. Beet armyworm moth numbers in traps in Salem and Cumberland counties have been low (>5 per night). Pyrethroid resistance is widespread in tomato fruitworm/corn earworm and beet armyworm, so other classes of insecticides should be used if management is needed.

Tomato fruitworm head visible emerging from a hole in a small green tomato.

Tomato fruitworm/corn earworm infesting a green tomato. Photo by Maria Cramer.

We continue to see high spider mites in many plantings. Spider mites tend to be worse in hot, dry conditions, and their populations can dramatically increase following broad-spectrum insecticides, which reduce their natural enemies. The first sign of their presence is often light-colored stippling seen on the top surface of tomato leaves. The mites causing this damage are usually found on the undersides of leaves, though with bad infestations mites will be found on the upper surface as well. When sampling spider mites, check 10 upper leaflets in at least 5 sites per field. The treatment threshold is 2 mites per leaflet on average (one of the individual leaves that makes up the compound tomato leaf). On farms where crop rotation is limited and the same miticides have been used for multiple years we’re seeing some miticide resistance — check whether and application has decreased mite populations, and if it did not work well, do not keep using it. Rotate between miticides and only treat when above threshold. Some products for spider mites in tomatoes include:

  • Nealta (group 25)
  • Oberon (group 23)
  • Portal (group 21A)
  • Agri-Mek (group 6) *7 day PHI
  • Kanemite (group 20B)
  • Acramite (group 20D) *3 day PHI
Tomato leaves with tiny yellow or white dots on visible on the top surface of the leaf.

Spider mite stippling visible when looking at tomato leaves from above. The spider mites are generally found on the undersides of the leaves. Photo by Maria Cramer.

Peppers

In terms of most insect pests, peppers have been looking very good. We have seen aphids, spider mites, and thrips at low levels so far, however it’s important to keep in mind that thrips can transmit TSWV to peppers as well, and so monitoring and staying on top of thrips populations is crucial. As with tomatoes, finding and roguing out infected plants is important as well (see picture below for symptoms on foliage and fruit).

Two pictures: the top picture shows a pepper plant with mottled yellow and green foliage. The bottom picture shows a cherry hot pepper that is green and red with many concentric circles on the skin.

A) TSWV symptoms on pepper foliage — note mottling and cupping of the foliage. B) Symptoms on cherry pepper fruit. Photos by Maria Cramer.

As a reminder, we have found pepper weevils on pepper weevil traps in Gloucester, Cumberland, and Salem Counties this summer. Read more about pepper weevil biology and management here. If you think you may have pepper weevil on your farm or are interested in monitoring, please contact Maria Cramer.

Cole Crops 

We are seeing many different kinds of caterpillars in fall cole crop plantings, including diamondback moth, imported cabbage worm, cabbage looper, cross-striped cabbageworm, and yellow striped armyworm. All cole crop seedlings can tolerate up to 10% infestation for these caterpillar. For heading cole crops between early vegetative and cupping, the treatment threshold is 30%. As heads form, the treatment threshold goes down to just 5% infestation. Sprayable Bt products (IRAC 11A) such as Dipel, Xentari, or Javelin can be effective on young imported cabbage worm, cross-striped cabbageworm, and yellow-striped armyworm caterpillars. Diamondback moth has resistance to many insecticide groups, and pyrethroids (IRAC 3A) and Bt products (IRAC 11A) are not effective for their management. Besides Bt, materials approved for caterpillar control include Entrust/Radiant (IRAC 5), Proclaim (IRAC 6), Torac (IRAC 21A), and Exirel (IRAC 28).  For Bt products and contact insecticides, coverage on the undersides the leaves is essential.

Caterpillar pests of cole crops. A) Diamondback moth — smooth and tapered at each end. B) Imported cabbageworm — fuzzy and not tapered. C) Cabbage looper — characteristic looping behavior. D) Cross-striped cabbage worm — distinctive stripes, usually occurs in groups. Photos A-C by Maria Cramer, photo D from iNaturalist COO.

We saw downy mildew in cole crops this week. This is a disease that develops best around 50-59ºF and our cool night temperatures are making prime conditions for disease development. Downy mildew may appears as light-colored lesions on the top of the leaves and as masses of white spores on the lower surface. Scout at least 25 plants per field (5 plants in 5 locations), checking the undersides for spores. If you have downy mildew, rotate or tank-mix chlorothalonil 6F (FRAC M05) with another product listed in the Mid-Atlantic Veg Guide for downy mildew in cole crops, rotating MOAs. Use overhead irrigation at times of the day when leaves can dry quickly to slow disease progression.

Downy mildew spore masses on the underside of a collard leaf. Photo by Renee Carter.

Pumpkins and Other Cucurbits

Cucurbit downy mildew was first reported on 7/11/25 on cucumbers in central NJ and has been found on cucumbers and cantaloupe at the Snyder Research Farm in Pittstown. Growers should be applying protectants on cucumbers and cantaloupes for cucurbit downy mildew at this time. As of this post, we still haven’t found any instances of the disease on pumpkins, squash, or watermelon. For information on how to build an effective cucurbit down mildew control program, please reference this post by Dr. Andy Wyenandt and consult the Mid-Atlantic Production Guide for additional materials that can be used.

Cucurbit downy mildew symptoms on the upper surface (A) and underside (B) of cucumber leaves and symptoms on cantaloupe (C). Photos by Amanda Quadrel

In pumpkins, we continue to see squash bug eggs and nymphs. Consider treating for squash bug if you see more than one egg mass or group of nymphs per plant (see photos below). Aphid and mite populations are also increasing in many locations. Consult the Mid-Atlantic Production Guide for a list materials appropriate for aphids or mites.

Squash bug eggs (A), newly hatched nymphs (B), and an adult (C). Photos by Amanda Quadrel

We have also seen aphid populations building in some fields. While not causing direct damage to the fruits, the honeydew produced by aphids can stick to the fruits and attract hornets or promote sooty mold growth, resulting in unsightly fruit. If a colony is found at three or more sites in a ten site sample, growers may wish to apply control measures. There are several options available, such as Assail, Fulfill, PQZ, Sefina, and Beleaf that are labeled for aphids and are safer for bees. If also dealing with heavy mite populations, Minecto Pro can target both pests, but has a higher toxicity to bees.

Melon aphids infesting a pumpkin leaf. Photo by Amanda Quadrel.

Powdery mildew has shown up in most scouted sites. If more than one leaf in a 50 leaf sample is infected, fungicide programs for powdery mildew should be initiated.

Powdery mildew on pumpkin leaf. Photo by Amanda Quadrel.

We have also seen isolated cases of anthracnose, bacterial wilt, plectosporium, and phythophthora root rot. A preventative diseases management plan based on recommendations from the Mid-Atlantic Production Guide is important for suppressing many of these diseases. If you suspect diseases in your pumpkins (or other cucurbits), reference the “Diagnosing important diseases in Cucurbit crops” guide or send/bring samples to Rutger’s Plant Diagnostic Lab.

As always, please consult the Mid-Atlantic Commercial Vegetable Production Guide for a comprehensive list of materials that are labeled for specific crops and pests. As always, be sure to follow label rates and application instructions.

The Vegetable IPM Program wishes to thank the following Field Technicians, without whom much of the information presented weekly here would not be available. This week Nick Vergara of the Southern team went back to Rowan University for his fall semester — we appreciate all the work he put in this summer!

Southern team: Renee Carter and Kris Szymanski

Northern team: Martina Lavender, Coco Lin, and Cassandra Dougherty

Vegetable IPM Update 9/11/24

Sweet Corn

Corn earworm (CEW) moth captures from northern and central blacklight and pheromone traps decreased substantially with cooler night temperatures over the past week.   Pheromone trap information is available from all northern and central sites, but is limited  from southern New Jersey.  With little information from South Jersey, growers there would be wise to assume numbers at least as high as those represented in the central and northern traps.  Should night time temperatures rebound, we should expect increases in CEW catch from both trap types.  We will use a combination of pheromone and blacklight trap types to derive silk spray schedules by region.  Silking corn is at risk of CEW infestation at this time.  Be sure to access information from this publication in the upcoming weeks to determine how frequently you should treat silking sweet corn to protect it from CEW infestation.

 

The highest nightly blacklight trap catches of CEW for the week ending 9/11/24 are as follows:

Hackettstown    11 Bellemeade   5 Farmingdale   3 Clinton   2
Denville   7 Blairstown   4 Georgetown   3 New Egypt   2
Allamuchy   6 Chester   3 Morrisotwn   3 Oldwick   2

The highest nightly pheromone trap catches of CEW for the week ending 9/11/24 are as follows:

Woodstown   59 Sparta   36 New Egypt   17
Hackettstown   41 Chester   31 Dayton   10
Green Creek   40 Georgetown   27 Matawan   10
Middle Valley   36 Allamuchy   24 South Branch   9

Thanks to Joe LaForest of Univ. of GA, and the Southern IPM Center for producing maps from our NJ CEW data!

No map will appear in this addition, as data came in to late to generate an image.  We will publish a map separately as soon as possible.

Using our current pheromone- based thresholds (30″ Hartstack trap) developed by the Univ. of Delaware, nightly corn earworm moth catches translate to:

0 moths – 6-7 day spray schedule

1 moth – 5 day spray schedule

2-20 moths – 4 day spray schedule

>20 moths – 3 day spray schedule

Silking Spray Schedules*:
South – 3-4 days

Central – 3 days

North – 3 days

*These recommendations are based on regional catches.  Adhere to tighter spray schedules if indicated by local trap catches.  Synthetic pyrethroids alone should NOT be used for corn earworm (CEW) protection on silking corn, or for fall armyworm (FAW) management at any stage.  Control with these materials is very inconsistent.

 

Beet Armyworm

Beet armyworm (BAW) numbers in pheromone traps in the Woodstown area of Salem County have gotten extremely high over the past week.  Thanks to a grower cooperator in that area, we know that catches range from 43 to 135/night over the past week in local traps.  This pest can cause significant injury on peppers as well as leafy greens like swiss chard, and kale.  Larvae are beginning to appear as far north as HunterdPlants covered in plasticon County, although it is likely that serious infestations are or will occur in southern NJ now.  Monitor pepper fields weekly for signs of feeding.  BAW larvae (photo at left) feed in the developing foliage in terminal growth of pepper plants.  Initially, leaves are skeletonized, but as larvae grow, they will move onto fruit and damage these as well.   In northern NJ, BAW is an occasional, and typically low level pest of cole crops.  Infestations tend to be very local for unknown reasons.  As with other armyworms, BAW is difficult to control with pyrethroid insecticides.  Effective materials include spinosyns (IRAC 5) and diamides (IRAC 28).

 

Cucurbit Crops

Melon aphids (photo at left) are now appearing in some fields of winter squash and pumpkins.  While not doing much damage to plants overall, these colonies can get quite large, and will deposit their sticky droppings on fruit below. This, in turn, supports the growth of sooty mold, and makes the fruit unsightly.  Further, the sticky droppings attract hornets, which can be an issue for harvesting crews or U-pickers.  Should melon aphid colonies appear in three or more sites in a ten site sample, consider applying an aphid specific material for control.  There are multiple options in the Pumpkin and Winter Squash section of the Commercial Vegetable Recommendations that have low toxicity to bees.

 

 

 

Corn Earworm Traps – 30″ Hartstack type

Growers wishing to purchase corn earworm pheromone traps to conduct their own on-farm monitoring should contact:

Mike “O” Olsowski

3510 Sutton Rd.

Geneva, NY  14456

Phone:  315-651-5929

Mike O manufactures these 30″ Hartstack traps in his shop.  These traps are the same as the ones we use currently in the IPM Program, and spray thresholds are based on this type.

Lures currently used in the Rutgers Vegetable IPM Program corn earworm pheromone traps are:

Hercon Luretape, available from Great Lakes IPM

Lures are placed in the clip at the base of the large cone, and a new one is added at two week intervals.

Welcome!

The Vegetable IPM Program welcomes Amanda Quadrel as the new Program Coordinator for southern New Jersey!  Amanda received her MS. from our Rutgers Entomology Department, working with spotted wing drosophila.  She has an excellent background in IPM tactics, and is currently meeting with growers and becoming familiar with some of our activities (though very late in the season) in the field.  Welcome, Amanda and good luck!