Search Results for: tomato spotted wilt virus

January 15, 2026 Andy Wyenandt, Maria Cramer and Amanda Quadrel

Monitoring for RB-Tomato Spotted Wilt Virus in transplant production

Tomato spotted wilt virus (TSWV) has caused significant problems for some fresh-market tomato and pepper growers in New Jersey the past few growing seasons. Although not uncommon, economic losses these past few years have been extensive.

TSWV is vectored by various species of thrips, a common vegetable insect pest that seems to be on the incline and very difficult to control in vegetable production throughout the state. The most important vector of TSWV is the western flower thrips, Frankliniella occidentalis. It’s mode of transmission is persistent propagative, meaning that thrips nymphs have to feed on a TSWV-infected plant, whereby followed by a short incubation period (lasting from hours to days), the virus is then persistently transmitted throughout the rest of the insect’s life span.

Importantly, TSWV cannot be passed from infected females to eggs; and TSWV is not transmitted in seed.

The western flower thrips and TSWV both have a wide host range! Western flower thrips host range includes: tomato, pepper, onion, celery, cucumber, lettuce, potato, basil, strawberry; a wide range of herbaceous ornamentals (e.g., impatiens, geranium, marigold, petunia, dahlia, gerbera daisy, carnation) as well as many common weeds (e.g., pigweed, chickweed, lambs quarter, thistle, galinsoga). TSMV can infect over 1,000 plant species from more than 90 plant families.

In 2022, samples of a TSWV-infected fresh market tomato variety with Sw-5b resistance were collected in southern New Jersey and sent for analysis. Results determined that RB (C118Y) TSWV was present in the state; and the strain found in New Jersey was similar to the RB TSWV found in fresh-market tomato from Mexico and processing tomato in California suggesting a high potential for its widespread movement. Since 2022, isolated cases of RB-TSWV have been found in New Jersey each growing season.

So, where do we go from here? Based on the isolated reports of TSWV being found on resistant fresh-market tomato in New Jersey the past few growing season, it does not appear that RB TSWV is currently widespread throughout the state. However, this may likely change.

All vegetable growers, those who produce their own transplants or bring them in, need to carefully evaluate their thrips monitoring and mitigation programs this winter and spring.

Start fresh. Prior to the transplant production season, clean and disinfect the greenhouse or any other structure where you might be holding transplants. Remove any weeds within and around the structure. Use sticky cards to monitor the potential carryover thrips population during the winter months, especially if you have any plant material in the greenhouse during those months.
Never produce or keep tomato or pepper transplants you start yourself or bring in, in the same greenhouse with any ornamental plants.
Segregate any transplants that are brought into your operation from your own transplants, as well as segregate different source of transplants as best you can.
Evaluate all incoming transplants for thrips damage.
Treat all incoming transplants with an insecticide immediately.
Use yellow sticky cards to continually monitor for thrips populations in the greenhouse from the start of the transplant season until the end.
Consider using biological or natural control(s) in the greenhouse.
The use of silver reflective mulches have been shown to reduce thrips populations in fields.
Develop a season-long insecticide program prior to the production season; from applying an insecticide at transplanting through cover sprays until harvest.
Monitor thrips populations and feeding damage in the field with regular scouting and sticky cards.
Closely monitor thrips feeding injury on pepper and tomato fruit during the production season.
Proper weed control is essential since many weeds may harbor the virus or infected thrips. This includes areas around the production field.
Rogue out any suspicious looking plant(s) prior to transplanting, or any suspicious looking plant early in the production season (e.g., any plant that starts to stunt out early) to help mitigate the within field spread.

Growers should continue to utilize TSWV-resistant tomato and pepper varieties realizing the effectiveness of those in limiting TSWV is becoming compromised. All growers need to continue to follow best management practices (such as those listed above) and pay careful attention to current weaknesses in their production practices and thrips control programs and adjust their management practices heading into 2026 growing season.

If you suspect RB-TSWV in transplant production or the field later this year please contact your county agent.

by: Andy Wyenandt, Maria Cramer, and Amanda Quadrel

References:

Macedo MA, Melgarejo T, Cespedes M, Rojas M, Lazicki P, Turini T, et al. (2024) An all-out assault on a dominant resistance gene: Local emergence, establishment, and spread of strains of tomato spotted wilt orthotospovirus (TSWV) that overcome Sw-5b-mediated resistance in fresh market and processing tomatoes in California. PLoS ONE 19(7): e0305402.

Tomato spotted wilt virus on pepper and tomato. Inga Meadows and Andy Cooper, NCSU 2024

Gautam et al., 2022. First report of a resistance-breaking strain of tomato spotted wilt orthotospovirus infecting Capsicum annuum with Tsw resistance gene in Texas. Plant Dis. 107:1958.

Filed Under: Organic Production, vegetable, Vegetable Crops Tagged With: Thrips, TSWV

May 28, 2025 Andy Wyenandt

Tomato Spotted Wilt Virus present in tomato

Tomato spotted wilt virus (TSWV) has caused significant problems for some fresh-market tomato and pepper growers in New Jersey the past few growing seasons. TSWV has already been detected in tomato this growing season. Although TSWV is not uncommon, economic losses these past few years have been extensive on some farms.

TSWV is vectored by various species of thrips, a common vegetable insect pest that seems to be on the incline and very difficult to control in vegetable production throughout the state. The most important vector of TSWV is the western flower thrips, Frankliniella occidentalis. It’s mode of transmission is persistent propagative, meaning that thrips nymphs have to feed on an infected plant, whereby followed by a short incubation period (lasting from hours to days), the virus is then persistently transmitted throughout the rest of the insect’s life span.

TSWV cannot be passed from infected females to eggs; and TSWV is not transmitted in seed.

In California and other tomato production regions, resistance-breaking (RB) strains (C118Y, C118F, T120N) of TSWV have recently been discovered that can overcome the single gene resistance (Sw-5b) bred into widely-grown processing and fresh-market tomato varieties. Recent research in TX has also shown that RB TSWV strains may increase western flower thrips fitness (ability to reproduce) by prolonging the adult period and increasing fecundity (i.e., a measure of an insect’s reproductive success, often expressed as the number of eggs or offspring produced by an insect) compared to non-RB and non-viruliferous controls. Unfortunately, the breakdown of genetic resistance along with the potential increase in TSWV-infected thrips reproduction rates, may lead to significant problems in thrips and TSWV control in New Jersey and elsewhere.

Recent work in Texas has shown that RB-TSWV can break resistance (conferred by the commonly deployed TSW-mediated single gene resistance) in TSWV-resistant pepper (Capsicum annuum) with varying levels of symptom development in both resistant and susceptible cultivars; with none being completely immune.

In October 2022, samples of a TSWV-infected fresh market tomato variety with Sw-5b resistance were collected in southern New Jersey and sent for analysis. Results determined that RB (C118Y) TSWV was present in the state; and the strain found in New Jersey was similar to the RB TSWV found in fresh-market tomato from Mexico and processing tomato in California suggesting a high potential for its widespread movement.

So, where do we go from here? Based on the isolated reports of TSWV and RB-TSWV being found on on a few farms the past few growing seasons, it does not appear that RB TSWV is currently widespread throughout the state. However, this may likely change and all growers need to be diligent.

All vegetable growers, those who produce their own transplants or bring them in, need to carefully evaluate their thrips monitoring and mitigation programs this winter.

Start fresh. Prior to the transplant production season, clean and disinfect the greenhouse or any other structure where you might be holding transplants. Remove any weeds within and around the structure. Use sticky cards to monitor the potential carryover thrips population during the winter months, especially if you have any plant material in the greenhouse during those months.
Never produce or keep tomato or pepper transplants you start yourself or bring in, in the same greenhouse with any ornamental plants.
Segregate any transplants that are brought into your operation from your own transplants, as well as segregate different source of transplants as best you can.
Evaluate all incoming transplants for thrips damage.
Treat all incoming transplants with an insecticide immediately.
Use yellow sticky cards to continually monitor for thrips populations in the greenhouse from the start of the transplant season until the end.
Consider using biological or natural control(s) in the greenhouse.
The use of silver reflective mulches have been shown to reduce thrips populations in fields.
Develop a season-long insecticide program prior to the production season; from applying an insecticide at transplanting through cover sprays until harvest.
Monitor thrips populations and feeding damage in the field with regular scouting and sticky cards.
Closely monitor thrips feeding injury on pepper and tomato fruit during the production season.
Proper weed control is essential since many weeds may harbor the virus or infected thrips. This includes areas around the production field.
Rogue out any suspicious looking plant(s) prior to transplanting, or any suspicious looking plant early in the production season (e.g., any plant that starts to stunt out early) to help mitigate the within field spread.

by: Andy Wyenandt and Kris Holmstrom

References:

Tomato spotted wilt virus on pepper and tomato. Inga Meadows and Andy Cooper, NCSU 2024

Gautam et al., 2022. First report of a resistance-breaking strain of tomato spotted wilt orthotospovirus infecting Capsicum annuum with Tsw resistance gene in Texas. Plant Dis. 107:1958.

Filed Under: Organic Production, vegetable, Vegetable Crops Tagged With: Thrips, TSWV

September 13, 2024 Andy Wyenandt

Resistance-breaking Tomato Spotted Wilt Virus present in tomato in New Jersey

TSWV is vectored by various species of thrips, a common vegetable insect pest that seems to be on the incline and very difficult to control in vegetable production throughout the state. The most important vector of TSWV is the western flower thrips, Frankliniella occidentalis. It’s mode of transmission is persistent propagative, meaning that thrips nymphs have to feed on an infected plant, whereby followed by a short incubation period (lasting from hours to days), the virus is then persistently transmitted throughout the rest of the insect’s life span.

TSWV cannot be passed from infected females to eggs; and TSWV is not transmitted in seed.

So, where do we go from here? Based on the isolated report of TSWV being found on resistant fresh-market tomato in New Jersey in 2022, and the more recent reports of it this year, it does not appear that RB TSWV is currently widespread throughout the state. However, this may likely change.

All vegetable growers, those who produce their own transplants or bring them in, need to carefully evaluate their thrips monitoring and mitigation programs this winter.

Start fresh. Prior to the transplant production season, clean and disinfect the greenhouse or any other structure where you might be holding transplants. Remove any weeds within and around the structure. Use sticky cards to monitor the potential carryover thrips population during the winter months, especially if you have any plant material in the greenhouse during those months.
Never produce or keep tomato or pepper transplants you start yourself or bring in, in the same greenhouse with any ornamental plants.
Segregate any transplants that are brought into your operation from your own transplants, as well as segregate different source of transplants as best you can.
Evaluate all incoming transplants for thrips damage.
Treat all incoming transplants with an insecticide immediately.
Use yellow sticky cards to continually monitor for thrips populations in the greenhouse from the start of the transplant season until the end.
Consider using biological or natural control(s) in the greenhouse.
The use of silver reflective mulches have been shown to reduce thrips populations in fields.
Develop a season-long insecticide program prior to the production season; from applying an insecticide at transplanting through cover sprays until harvest.
Monitor thrips populations and feeding damage in the field with regular scouting and sticky cards.
Closely monitor thrips feeding injury on pepper and tomato fruit during the production season.
Proper weed control is essential since many weeds may harbor the virus or infected thrips. This includes areas around the production field.
Rogue out any suspicious looking plant(s) prior to transplanting, or any suspicious looking plant early in the production season (e.g., any plant that starts to stunt out early) to help mitigate the within field spread.

by: Andy Wyenandt and Kris Holmstrom

References:

Tomato spotted wilt virus on pepper and tomato. Inga Meadows and Andy Cooper, NCSU 2024

Gautam et al., 2022. First report of a resistance-breaking strain of tomato spotted wilt orthotospovirus infecting Capsicum annuum with Tsw resistance gene in Texas. Plant Dis. 107:1958.

Filed Under: Organic Production, vegetable, Vegetable Crops Tagged With: Thrips, TSWV

February 25, 2026 Amanda Quadrel and Maria Cramer

Have a plan for managing thrips and TSWV in tomatoes and peppers in 2026

Thrips and tomato spotted wilt virus (TSWV) management were major challenges for multiple South Jersey growers in 2025, as well as in the previous few years. Several growers reported losing entire tomato plantings to the virus. Peppers were less impacted than tomatoes, but TSWV outbreaks did occasionally occur. As we move into pepper and tomato transplant production and the growing season for greenhouse tomatoes, having a multi-pronged approach for managing thrips and TSWV will give you the best chance of protecting your crop and avoiding losses. Below are key practices that can help keep thrips populations as low as possible:

Start clean. When transplants are infested with thrips prior to planting out, field infestations tend to occur early and be very difficult to control. To start clean:

Never produce transplants in the same greenhouse with ornamentals. Ornamentals can harbor thrips and many are asymptomatic hosts for TSWV.
Monitor thrips in planthouse with sticky cards and scouting (Fig. 1). There are no established thresholds for thrips in the greenhouse, but many growers use the first appearance of thrips as an action threshold.
Keep greenhouses and high tunnels weed-free. Weeds can host both thrips and TSWV.
If buying in transplants, segregate and monitor incoming transplants to ensure that they are not bringing in thrips.
Treat transplants with imidacloprid (e.g. Admire) or Cyantriniliprole (Verimark) before setting in the field

A yellow rectangular sticky card held to a stake with a clothespin has caught several small insects.

Fig. 1. A sticky card being used to monitor greenhouse pests. Photo by S. Rettke.

Manage plantings to prevent the spread of thrips and TSWV from alternative hosts into tomato plantings. Thrips are attracted to pollen-producing plants, so populations can build up on plants that flower early, such as strawberries and small grains, then move into tomato plantings. Additionally, thrips can also overwinter on weeds. Using these facts, reduce the movement of thrips into tomato plantings by:

Controlling weeds throughout the farm, especially in and around high tunnels
Separating field plantings from greenhouses/tunnels, strawberry fields, and small grains
Separating successive field plantings as much as possible. This way, if thrips and/or TSWV get out of control in one planting, they will not move directly into the next planting.
Scouting for tomato spotted wilt virus symptoms (Fig. 2). Immediately rogue symptomatic plants to avoid secondary spread within the field.

Fig. 2. TSWV symptoms in tomato: a) curling and yellowing foliage symptoms, b) distortion and brown shoulder symptoms on green fruit, and c) bulls-eye symptoms on ripe fruit. Photos by M. Cramer.

Use metallized plastic and resistant varieties.

Use metallized plastic mulch when possible (Fig. 3). Metallized mulches reflect sunlight, disrupting thrips navigation and making it harder for them to colonize plants. These plastics are widely used in states like Florida that have historically had serious thrips problems. Because these mulches reflect solar radiation, they lower bed temperatures, and will slow down tomato growth early in the season. This should be taken into account when planning to use them.
Use TSWV resistant tomato and pepper varieties. While some farms have reported resistance-breaking TSWV, others continue to report that resistance is still holding up.

Fig. 3. Metallized plastic laid in the fall to control onion thrips in alliums. Photo by A. Quadrel.

Use best practices around insecticides. Thrips are difficult to manage with insecticides because they tend to hide in hard to reach parts of the plant or in the soil as well as their rapid ability to develop resistance. For example, many thrips populations in south Jersey are resistant to Radiant (IRAC 5), making this insecticide ineffective for management. Pyrethroid (IRAC 3) resistance is also widespread. Many of the insecticides labeled for thrips are only partly effective, and none are able to “knock down” high populations. To get the best efficacy out of insecticides:

Know what your populations are: Monitor thrips populations and treat when populations start building, but are still low.
- Scout 5- 10 locations in field at least once a week
- At each location in the field, pick a group of 5 consecutive plants and check 2 leaves on each plant (10 leaves total per location)
- Count the number of thrips on the leaves (Fig. 4). Research from North Carolina shows that the species of thrips vectoring TSWV (western flower thrips) are most reliably found on the leaves rather than the flowers
- Threshold: Action should be taken if counts are increasing towards ~ 5 thrips per 10 leaves on average
Rotate modes of action as much as possible. We believe that thrips populations tend to be highly localized, and thus you are managing insecticide resistance for your population of thrips specifically. The more you manage resistance, the more product options you will continue to have.
Monitor thrips populations after treatment to assess efficacy (some systemic products, such as Beleaf and Verimark may take several days to ~a week to impact thrips populations)

Note: The vegetable IPM program offers scouting services throughout New Jersey if you are unable to scout your plantings (you can find a description of services here). We also offer training for scouts employed by growers. Finally, private companies can also provide scouting services.

Fig. 4. Five thrips on a tomato leaf.

Plan what products you will use and when. The following table lists conventional products that can be used for tomato pest management. Choose products from a variety of IRAC groups to prevent resistance development and prolong efficacy.

IRAC group	Product name	Ai	Efficacy * = suppression only	Notes on use
1A	Lannate	Methomyl	Good	New EPA restrictions on annual applications (<13 lbs AI/acre/year) and mitigations for runoff and drift. Not labeled specifically for thrips in tomatoes, but can be used
1B	Dimethoate	Dimethoate	Good	Not labeled specifically for thrips in tomatoes, but can be used
4A	Admire	Imidacloprid	Good	Only labeled for tobacco thrips. For treating transplants before transplanting
5	Radiant/ Entrust	Spinetoram/ Spinosad	Excellent, except where resistant	No more than 3 applications in a season. Widespread resistance issues in South Jersey
13	Pylon	Chlorfenapyr	Excellent	Only for greenhouse tomato production– i.e., not for transplants or field production. Not to be used on tomatoes that are <1” diameter at harvest.
15	Rimon	Novaluron	Good*	Foliar. No more than 2 applications against thrips in a year. Can be used in greenhouses and high tunnels. Larvae only
21A	Torac	Tolfenpyrad	Fair	Foliar. No more than 2 applications in a season
23	Movento	Spirotetramat	?	Foliar. No more than 2 applications in a season (at 5 fl oz/A thrips rate). Larvae only
28	Harvanta	Cyclaniliprole	Fair*	Limit of 3 applications per season (at 16.4 fl oz/A thrips rate)
28	Verimark	Cyantraniliprole	Fair*	Tray drench just prior to planting or drip irrigation. No more than 2 applications per year. Limits when ai is being used foliarly (e.g. Exirel) as well
28	Exirel	Cyantraniliprole	Fair*	Foliar. Recommend early in the season for new transplants. Limitations on ai use
29	Beleaf	Flonicamid	Excellent	Only labeled for thrips when used through drip. No more than 2 applications per year
30	Incipio	Isocycloseram	Excellent	New for 2026. No more than 2 applications per year

When using pesticides, the label is the law. Always make sure the product you use is registered in your state and for your crop(s). Follow all application restrictions.

Biological insecticides. There are many biological products that are labeled for tomatoes in the greenhouse, tunnel, and field. While we do not have efficacy information for these, some growers have reported good results in tunnels and greenhouses with Grandevo WDG (Chromobacterium subtsugae and spent fermentation media), LALGUARD M52 OD (active Metarhizium brunneum), and Bronte (inactivated Burkholderia rinojensis cells and spent fermentation media). Biological insecticides may have specific storage and handling instructions in order to achieve maximum efficacy.

In conclusion, use a multi-strategy approach for thrips and TSWV management. In particular, use resistant varieties and preventative practices to reduce thrips populations and TSWV spread on your farm. When using insecticides, time applications based on action thresholds, monitor efficacy, and rotate IRAC groups in order to prevent the development of insecticide resistance.

By: Maria Cramer, Amanda Quadrel, and Andy Wyenandt.

Filed Under: Organic Production, vegetable, Vegetable Crops Tagged With: insecticide resistance management, IPM, tomato, tomato spotted wilt virus

July 9, 2025 Andy Wyenandt

Bacterial leaf spot, copper resistance, hot water seed treatment, and viruses

Copper resistance in bacterial leaf spot of tomato and pepper crops has been detected at a high level in New Jersey the past few summers. While not surprising, copper resistance has been known to develop for decades now. Copper applications for the control of bacterial diseases in many crops has been a mainstay for decades now and is often applied in weekly protectant fungicide programs. With help from Dr. Nrupali Patel and Dr. Don Kobayashi, bacteriologists in the Department of Plant Biology located on the New Brunswick campus, a (NJ-VGA funded) survey was initiated to determine which species of bacterial leaf spot are most prevalent in New Jersey tomato and pepper crops. Bacterial leaf spot can be caused by four species of Xanthomonas: X. euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri. Currently, there are four races of BLS found in tomato (T1-T4; one for each of the 4 species stated above) and eleven races found in pepper (0-10). Differential tests in southern New Jersey using various bell pepper lines over the past 15 years has suggested that the number of races of BLS in pepper has increased over time; with all races present in the State to date. Lab testing results from samples collected from the small number of NJ vegetable farms the last three summers has shown the presence of X. euvesicatoria in pepper, as well as X. euvesicatoria and X. perforans in both tomato and pepper in the state, with ~60% of all samples testing positive for copper resistance.

[Read more…]

Filed Under: Vegetable Crops Tagged With: bacterial leaf spot, copper resistance

July 7, 2025 Andy Wyenandt

Tobacco Streak Virus (TSV) found on tomato in New Jersey

Tobacco Streak Virus (TSV) was found on fresh-market tomato this past week in southern New Jersey. TSV has a host range of close to 200 species, including cranberry, tobacco, tomato, pepper, asparagus, bean, soybean, mustard, radish, a number of ornamental hosts as well as weeds such as thistle, field bindweed, and jimson weed. Like Tomato Spotted Wilt Virus (TSWV), the Tobacco Streak Virus is also vectored by thrips. TSV can be seed-borne (reported in some hosts), spread via pollen, and mechanically transmitted. Symptoms can vary significantly depending on the host. Infected plants may have downward leaf curling, show black streaks on leaves and stems, chlorosis, stunted growth, deformed growing tips, ring spots, and flower drop. There is no genetic resistance to TSV in tomato and management should focus on keeping thrips populations as low as possible, scouting on a regular, removing infected plants, and knowing your weed population (as a potential source). The only method to correctly identify TSV is through serological tests such as ELISA.

For more information on Tomato Spotted Wilt Virus please click here.

Filed Under: Vegetable Crops Tagged With: tomato, TSV, virus

Search Results for: tomato spotted wilt virus

Monitoring for RB-Tomato Spotted Wilt Virus in transplant production

Tomato Spotted Wilt Virus present in tomato

Resistance-breaking Tomato Spotted Wilt Virus present in tomato in New Jersey

Have a plan for managing thrips and TSWV in tomatoes and peppers in 2026

Bacterial leaf spot, copper resistance, hot water seed treatment, and viruses

Tobacco Streak Virus (TSV) found on tomato in New Jersey

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