Search Results for: corn borer

Greetings from the Veg IPM team!

Sweet Corn

Corn earworm moth captures are increasing, leading to 3- or 4-day spray intervals being needed throughout the state. When temperatures are 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). Corn earworm 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.

 

Fall armyworm (FAW) infestations are beginning to pick up in some 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 age, 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 will have a dark head capsule with a distinct, inverted Y-shaped suture (B). 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.

 

We are seeing a significant amount smut it sweet corn. Normally, smut infects the ears, however we have seen smut growths on vegetative stages (leaves and tassels) as well. Smut was prevalent in our area in 2024, and you can read more about it in an update written last year. Smut is rarely economic and there are no effective treatments for it. Being able to correctly identify it can help rule out other plant problems.

 

Tomatoes

Throughout New Jersey we’re continuing to see high thrips counts both in tunnels and in the field, although numbers have been higher in tunnels. We consider more than 5 thrips on 10 leaves a high count. Other guides suggest 3-5 thrips per flower or the presence of stippling damage on fruit to be a treatment threshold. Thrips management is especially important because of their ability to vector tomato spotted wilt virus (TSWV), a growing concern in New Jersey where we have resistance-breaking strains. We have seen several locations in our scouting program with small outbreaks of TSWV (in both peppers and tomatoes) so far. Scouting and roguing out these plants while continuing to manage thrips should help prevent serious losses. Additionally, follow best management practices for reducing TSWV risk throughout the season.

Caterpillar pests have begun showing up in throughout the state. We’ve seen some fruit damage, and tomato fruitworm (AKA corn earworm), beet armyworm, 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. Pyrethroid resistance is widespread in tomato fruitworm/corn earworm and beet armyworm, so other classes of insecticides should be used if management is needed.

With consistent hot temperatures, we’re seeing more spider mites in tomato plantings. Spider mites tend to be worse in hot, dry conditions, and especially thrive in tunnels. Their populations often 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. For spider mites, Nealta (IRAC 25) and Oberon (IRAC 23) are effective materials that are more friendly to beneficial insects, but Portal (IRAC 21A) and other materials can also be used to manage populations.

 

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 previous section for an example of TSWV symptoms in peppers.

With drying weather, peppers have been fairly disease-free, but we have seen instances of anthracnose. Anthracnose is an important disease to scout for and be able to identify as removing infected fruit and strip-picking surrounding fruit is key to managing its spread. Your fungicide program can also help manage anthracnose — for more information, read more here.

As a reminder, in June we saw several pepper weevils on pepper weevil traps in Cumberland and Salem Counties. 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 no longer seeing many flea beetles in cole crops, but we continue to see caterpillar activity. Treatment thresholds vary between crops and growth stage, but 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 caterpillars. Other materials approved for caterpillar control include Entrust/Radiant (IRAC 5), Proclaim (IRAC 6), Torac (IRAC 21A), and Exirel (IRAC 28). Diamondback moth (the primary caterpillar found in southern NJ) has resistance to many insecticide groups, and pyrethroids (IRAC 3A) are not effective for their management. For Bt products and contact insecticides, coverage on the undersides the leaves is essential.

 

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 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.

In pumpkins, we’ve seen few insect issues, although adult squash bugs and egg masses are starting to appear. Consider treating for squash bug if you see more than one egg mass or group of nymphs per plant (see photos below).

 

Powdery mildew is also beginning to pick up. If more than one leaf in a 50 leaf sample is infected, fungicide programs for powdery mildew should be initiated.

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:

Southern team: Renee Carter, Kris Szymanski, and Nick Vergara

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

Greetings from the Veg IPM team!

Sweet Corn

Corn earworm moth captures are increasing, leading to 3- or 4-day spray intervals being needed throughout the state. When temperatures are 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). Corn earworm 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.

 

Fall armyworm (FAW) infestations are beginning to pick up in some 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 age, 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 will have a dark head capsule with a distinct, inverted Y-shaped suture (B). 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.

 

Tomatoes

Throughout New Jersey we’re continuing to see high thrips counts both in tunnels and in the field, although numbers have been higher in tunnels. We consider more than 5 thrips on 10 leaves a high count. Other guides suggest 3-5 thrips per flower or the presence of stippling damage on fruit to be a treatment threshold. Thrips management is especially important because of their ability to vector tomato spotted wilt virus (TSWV), a growing concern in New Jersey where we have resistance-breaking strains. We have seen several locations in our scouting program with small outbreaks of TSWV (in both peppers and tomatoes) so far. Scouting and roguing out these plants while continuing to manage thrips should help prevent serious losses. Additionally, follow best management practices for reducing TSWV risk throughout the season.

Caterpillar pests have begun showing up in throughout the state. We’ve seen some fruit damage, and tomato fruitworm (AKA corn earworm), beet armyworm, 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. Pyrethroid resistance is widespread in tomato fruitworm/corn earworm and beet armyworm, so other classes of insecticides should be used if management is needed.

With consistent hot temperatures, we’re seeing more spider mites in tomato plantings. Spider mites tend to be worse in hot, dry conditions, and especially thrive in tunnels. Their populations often 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. For spider mites, Nealta (IRAC 25) and Oberon (IRAC 23) are effective materials that are more friendly to beneficial insects, but Portal (IRAC 21A) and other materials can also be used to manage populations.

 

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 previous section for an example of TSWV symptoms in peppers.

As a reminder, in June we saw several pepper weevils on pepper weevil traps in Cumberland and Salem Counties. 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 no longer seeing many flea beetles in cole crops, but we continue to see caterpillar activity. Treatment thresholds vary between crops and growth stage, but 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 caterpillars. Other materials approved for caterpillar control include Entrust/Radiant (IRAC 5), Proclaim (IRAC 6), Torac (IRAC 21A), and Exirel (IRAC 28). Diamondback moth (the primary caterpillar found in southern NJ) has resistance to many insecticide groups, and pyrethroids (IRAC 3A) are not effective for their management. For Bt products and contact insecticides, coverage on the undersides the leaves is essential.

 

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 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.

In pumpkins, we’ve seen few insect issues, although adult squash bugs and egg masses are starting to appear. Consider treating for squash bug if you see more than one egg mass or group of nymphs per plant (see photos below).

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:

Southern team: Renee Carter, Kris Szymanski, and Nick Vergara

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

Greetings from the Veg IPM team!

Sweet Corn

Corn earworm moth captures are increasing in the southern part of the state leading to 3- or 4-day spray intervals being needed at all trapping locations south of interstate 195. When temperatures are 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). Corn earworm 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. We’ve also seen some very minor instances of European corn borer, fall armyworm, and corn earworm feeding in pre-silking corn. In the pre-tassel stage, we use a treatment threshold of 12% infestation of these types of caterpillars, and sightings have been far below this so far.

Tomatoes

Throughout New Jersey we’re continuing to see high thrips counts both in tunnels and in the field, although numbers have been higher in tunnels. We consider more than 5 thrips on 10 leaves a high count. Other guides suggest 3-5 thrips per flower or the presence of stippling damage on fruit to be a treatment threshold. Thrips management is especially important because of their ability to vector tomato spotted wilt virus (TSWV), a growing concern in New Jersey where we have resistance-breaking strains. We have seen several locations in our scouting program with small outbreaks of TSWV (in both peppers and tomatoes) so far. Scouting and roguing out these plants while continuing to manage thrips should help prevent serious losses. Additionally, follow best management practices for reducing TSWV risk throughout the season.

Caterpillar pests have begun showing up in southern NJ plantings in the last week. We’ve seen some fruit damage, and tomato fruitworm (AKA corn earworm), beet armyworm, 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. Pyrethroid resistance is widespread in tomato fruitworm/corn earworm and beet armyworm, so other classes of insecticides should be used if management is needed.

With consistent hot temperatures, we’re seeing more spider mites in tomato plantings. Spider mites tend to be worse in hot dry conditions, and especially thrive in tunnels. Their populations often 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. For spider mites, Nealta (IRAC 25) and Oberon (IRAC 23) are effective materials that are more friendly to beneficial insects, but Portal (IRAC 21A) and other materials can also be used to manage populations.

We’re also seeing limited aphid activity in tomatoes. If dealing with primarily aphids, products such as Beleaf (IRAC 29) are recommended, especially if plants have reached the flowering stage. However, natural enemies often control aphids, so if counts are low and natural enemies like lacewings, lady beetles, or parasitoid wasps are present, you may avoid sprays.

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 previous section for an example of TSWV symptoms in peppers.

As a reminder, in June we saw several pepper weevils on pepper weevil traps in Cumberland and Salem Counties. 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 no longer seeing many flea beetles in cole crops, but we continue to see caterpillar activity. Treatment thresholds vary between crops and growth stage, but 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 caterpillars. Other materials approved for caterpillar control include Entrust/Radiant (IRAC 5), Proclaim (IRAC 6), Torac (IRAC 21A), and Exirel (IRAC 28). Diamondback moth (the primary caterpillar found in southern NJ) has resistance to many insecticide groups, and pyrethroids (IRAC 3A) are not effective for their management. For Bt products and contact insecticides, coverage on the undersides the leaves is essential.

Pumpkins

So far pumpkins have looked very clean in terms of insects. We have 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:

Southern team: Renee Carter, Kris Szymanski, and Nick Vergara

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

Greetings from the Veg IPM team! We hope that you’re all enjoying the holiday and the nice weather for this weekend.

Sweet Corn

Moth captures in much of the state (see map) have decreased over the past week and a half, but a 4-day spray schedule is still necessary for most growers at this time. When temperatures are 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). Corn earworm 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. We’ve also seen some very minor instances of European corn borer, beet armyworm, and corn earworm feeding in pre-silking corn, as well as our first sighting of fall armyworm (found in Burlington County). In the pre-tassel stage, we use a treatment threshold of 12% infestation of these types of caterpillars, and sightings have been far below this so far.

Tomatoes

Throughout New Jersey we’re continuing to see high thrips counts both in tunnels and in the field, although numbers have been higher in tunnels. We consider more than 5 thrips on 10 leaves a high count. Other guides suggest 3-5 thrips per flower or the presence of stippling damage on fruit to be a treatment threshold. Thrips management is especially important because of their ability to vector tomato spotted wilt virus (TSWV), a growing concern in New Jersey where we have resistance-breaking strains. TSWV has already been seen on farms this season. Thrips management can be especially challenging in high tunnels due to a lack of products. Minecto Pro (IRAC 28 + 6) and Exirel (IRAC 28) can be used in tunnels, but only suppress thrips populations (this means they reduce numbers, but do not eradicate them). In the field, Entrust/Radiant (IRAC 5) can be used as well as Torac (IRAC 21A) and Harvanta (IRAC 28). We do not recommend pyrethroids or neonicotinoids for thrips due to resistance in different thrips species. Refer to the previous link for a complete list of best management practices for thrips and TSWV.

Caterpillar pests have begun showing up in southern NJ plantings in the last week. We’ve seen some fruit damage, and tomato fruitworm (AKA corn earworm), beet armyworm, 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. Pyrethroid resistance is widespread in tomato fruitworm/corn earworm and beet armyworm, so other classes of insecticides should be used if management is needed.

We’re also seeing limited aphid and spider mite activity in tomatoes. If dealing with primarily aphids, products such as Beleaf (IRAC 29) are recommended, especially if plants have reached the flowering stage. However, natural enemies often control aphids, so if counts are low and natural enemies like lacewings, lady beetles, or parasitoid wasps are present, you may avoid sprays. For spider mites, Nealta (IRAC 25) is an effective material that is more friendly to beneficial insects, but Portal (IRAC 21A) and other materials can also be used to manage populations.

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.

In southern New Jersey, pepper weevils are periodically introduced from other regions of the United States via the processing industry, so we have been using pheromone traps to monitor their populations. Single pepper weevils have been found on traps at locations in Cumberland and Salem counties. Because established pepper weevil populations are virtually impossible to eradicate and can lead to total losses, the presence of a single weevil triggers routine insecticide applications through the end of pepper harvest. Many populations of pepper weevils are resistant to pyrethroids, and insecticide classes should be rotated when managing them to prevent further resistance. Currently available chemistries suppress, but do not eradicate, pepper weevils. 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 no longer seeing many flea beetles in cole crops, but we continue to see caterpillar activity. Treatment thresholds vary between crops and growth stage, but 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 caterpillars. Other materials approved for caterpillar control include Entrust/Radiant (IRAC 5), Proclaim (IRAC 6), Torac (IRAC 21A), and Exirel (IRAC 28). Diamondback moth (the primary caterpillar found in southern NJ) has resistance to many insecticide groups, and pyrethroids (IRAC 3A) are not effective for their management. For Bt products and contact insecticides, coverage on the undersides the leaves is essential.

Diseases

With the heavy rainfall over the last week, conditions have been favorable for diseases to spread. We’re still seeing bacterial and fungal issues in peppers and tomatoes, but we have also started to see issues like Alternaria in cole crops. To prevent the spread of disease, avoid working fields when foliage is wet and continue to use resistant varieties when possible. In tunnels, leaf mold is becoming a prevalent problem as well. Be sure to vent the structure regularly to reduce humidity. Mural (FRAC 7 + 11) is labeled for greenhouse use.

 

 

 

 

 

 

 

 

 

 

 

 

 

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, Kris Szymanski, and Nick Vergara

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

Greetings from the Veg IPM team! We hope you all stayed cool during the heat wave this past week!

Sweet Corn

Early plantings of sweet corn are silking throughout New Jersey. Moth captures in much of the state (see map) have generally decreased, but a 4-day spray schedule is still necessary for most growers at this time. When temperatures are 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). Corn earworm 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. We’ve also seen some instances of European corn borer and corn earworm feeding in tassels of scouted corn, but for the most part, their numbers have not been high enough to warrant control efforts prior to silking.

Tomatoes

Throughout New Jersey we’re continuing to see high thrips counts both in tunnels and in the field, although numbers have been higher in tunnels. We consider more than 5 thrips on 10 leaves a high count. Other guides suggest 3-5 thrips per flower or the presence of stippling damage on fruit to be a treatment threshold. Thrips management is especially important because of their ability to vector tomato spotted wilt virus (TSWV), a growing concern in New Jersey where we have resistance-breaking strains. TSWV has already been seen on farms this season. Thrips management can be especially challenging in high tunnels due to a lack of products. Minecto Pro (IRAC 28 + 6) and Exirel (IRAC 28) can be used in tunnels, but only suppress thrips populations (this means they reduce numbers, but do not eradicate them). In the field, Entrust/Radiant (IRAC 5) can be used as well as Torac (IRAC 21A) and Harvanta (IRAC 28). We do not recommend pyrethroids or neonicotinoids for thrips due to resistance in different thrips species. Refer to the previous link for a complete list of best management practices for thrips and TSWV.

We’re also seeing limited aphid and spider mite activity. If dealing with primarily aphids, products such as Beleaf (IRAC 29) are recommended, especially if plants have reached the flowering stage. However, natural enemies often control aphids, so if counts are low and natural enemies like lacewings, lady beetles, or parasitoid wasps are present, you may avoid sprays. For spider mites, Nealta (IRAC 25) is an effective material that is more friendly to beneficial insects, but Portal (IRAC 21A) and other materials can be used to manage populations. Colorado potato beetles are especially prevalent in eggplants. Please consult the Mid-Atlantic Commercial Vegetable Production guide for appropriate materials for CPB control.

Cole Crops 

Flea beetle activity seems to be slowing down some, but they are still active in some cole crops. This year, they have been especially prevalent in lacinato kale, Napa cabbage and bok choy. Young plants are especially vulnerable to attack from flea beetles. The treatment threshold for flea beetles in heading cole crops is 50% infestation.

We continue to see caterpillar activity in heading cole crops. Treatment thresholds vary between crops and growth stage, but 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. For very small caterpillars, sprayable Bt products (IRAC 11A) such as Dipel, Xentari, or Javelin can be effective on young imported cabbage worm caterpillars. Other materials approved for caterpillar control include Entrust/Radiant (IRAC 5), Proclaim (IRAC 6), Torac (IRAC 21A), and Exirel (IRAC 28). Diamondback moth (the primary caterpillar found in southern NJ) has resistance to many insecticide groups, and pyrethroids (IRAC 3A) are not effective for their management. For Bt products and contact insecticides, coverage on the undersides the leaves is essential.

Diseases

With the heavy rainfall over the last week, conditions have been favorable for diseases to spread. We’re still seeing bacterial and fungal issues in tomatoes, but we have also started to see issues like Alternaria in cole crops. To prevent the spread of disease, avoid working fields when foliage is wet and continue to use resistant varieties when possible. In tunnels, leaf mold is becoming a prevalent problem as well. Be sure to vent the structure regularly to reduce humidity. Mural (FRAC 7 + 11) is labeled for greenhouse use.

 

 

 

 

 

 

 

 

 

 

 

 

 

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