Greetings from the Veg IPM team!
Sweet Corn
Many farms have wrapped up sweet corn for the season, but for those with corn still silking, moth pressure remains high. Corn earworm trap counts indicate at least a 4-day spray interval for all New Jersey locations this week. Refer to the map below to see this week’s CEW pressure throughout the state. With temperatures falling in the next week, most locations will no longer need to shorten the spray interval by a day. Remember, rotation is important for avoiding resistance, so rotate between the four IRAC groups 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 are 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.
Caterpillar pests in the whorl and tassel stage. Fall armyworm (FAW) has dropped off significantly this week. Still, if you have whorl-stage corn it is a good idea to scout for it. 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. For treatment, we recommend using products other than diamides (IRAC Group 28), 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.
Aphids. Aphids have also dropped off significantly in the past weeks. 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 still above your tolerance 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.
Tomatoes and Peppers
Thrips and TSWV. Thrips have slowed down with lower temperatures and general declines in tomato plant health due to stress and diseases as the season has progressed. We are still seeing some spread of tomato spotted wilt virus, but it has slowed compared to earlier in the season. If management of thrips no longer makes sense economically, we encourage destroying older plantings to try to reduce populations of thrips and the reservoir of the virus on farms. See our previous article for detailed information on managing thrips and TSWV in tomatoes.
Spider mites. Be on the look out for spider mites, but populations have been lower than last season at this time. Whether or not it makes sense to treat depends on the stage of the crop. We do not recommend treating tomato fields that are approaching the end of picking.
Beet armyworm. We track beet armyworm with pheromone traps deployed in south Jersey. Beet armyworm is an occasional pest of peppers, swiss chard, and beets and can cause serious damage and crop loss if outbreaks occur unexpectedly. Our traps in Salem county continue to find high moth counts (30+ moths per night), so we suggest scouting susceptible crops for caterpillars and damage. Traps in Cumberland county continue to have low captures (<5 moths per night).
Caterpillar pests in tomato. Top: Corn earworms come in a number of colors, including this pinkish-red. Note the hairs which are distinctive on CEW. Bottom: Cabbage looper. Note that rear-end is larger than front of the caterpillar. Photos by Maria Cramer.
Other caterpillar pests.
We continue to see pressure in tomatoes from yellow striped armyworm, tomato fruit worm (AKA corn earworm), and cabbage looper. Cabbage looper has been especially prevalent in tomato plantings over the past few weeks. While cabbage looper feeds primarily on foliage, it may also directly damage fruits (see image below). We suggest scouting tomatoes for worm damage and the presence of caterpillars. Giving the plant a good shake or using a beat tray can help detect the presence of caterpillars. Most products listed in the 2026/2027 Mid-Atlantic Commercial Vegetable Production Guide for caterpillar pests will be effective, but keep in mind that many species have pyrethroid resistance, so group 3 insecticides should not be used.
Cucurbits
Cucurbit Downy Mildew (CDM) Status. Cucurbit Downy Mildew was detected in NJ at the end of August. This includes CDM on butternut squash and cucumbers at the RAREC research farm (Bridgeton), and Snyder research farm (Pittstown). All growers should be applying downy mildew-specific fungicides to their cucurbit plantings. Keep in mind that products that control powdery mildew won’t necessarily control downy mildew, and vice versa. Be sure to rotate multiple products with different FRAC codes to reduce the risk of resistance development. For more detailed information about the disease and how to build an effective fungicide rotation, you can read this article by Andy Wyenandt.
Melon aphids infesting a pumpkin leaf. Photo by Amanda Quadrel.
Melon aphids. In most plantings, aphid populations have been relatively low. While aphids do not cause direct damage to the crops, the honeydew they secrete can lead to unsightly sooty mold growth on fruits. Honeydew can also attract yellow jackets, which can be hazardous to crews and U-pickers. Scout for aphids and consider treating for them if you find aphid clusters in more than one site (out of a ten site sample).
Cole Crops
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.
Scouted cole crops continue to have varying levels of caterpillar activity. The caterpillar threshold is 20% infestation for crops still in the leafy/early cupping stage. Once heads begin to form, the threshold drops to 5%. For young caterpillars (especially imported cabbage worm), Bt products such as Dipel or Xentari are IPM friendly options. 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), Exirel (IRAC 28), and Incipio (IRAC 30). For Bt products and contact insecticides, coverage on the undersides the leaves is essential.
Alternaria on broccoli. Photo by Amanda Quadrel.
In some locations, we’ve also seen some low incidence of diseases such as alternaria, black rot, and downy mildew. Note that downy mildew in brassicas is not the same species that affects cucurbits. Brassica downy mildew is a disease that develops best around 50-59ºF so we will likely
Downy mildew on a collard leaf. Photo by Maria Crame
see more progress with the disease temperatures cool down. 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.
As a reminder, the new 2026/2027 Mid-Atlantic Commercial Vegetable Production Guide is now available for free online (click here) or as spiral-bound hard copies that can be purchased at your local county extension office. Consult this guide for a more comprehensive list of materials that are labeled for specific crops and pests.
We want to give a huge thanks to our scouting team for keeping an eye on things for us throughout the season!
North NJ: James Johnson and Cassandra Dougherty
South NJ: Renee Carter, Peter Combs, Mar Sherman, and Kris Szymanski
Authors: Amanda Quadrel (Northern NJ Veg IPM coordinator) and Maria Cramer (Southern NJ Veg IPM coordinator)
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