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.

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.

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.

A) TSWV on a tomato leaf. Note the circle-shaped brown lesions. B) TSWV on a pepper plant. Note the distortion of leaves all over the plant as well as the yellow wavy lines and circles visible on leaves. Photos by Maria Cramer.

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.

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

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.

Left: Diamondback moth caterpillar, showing characteristic tapering at each end. Right: Imported cabbageworm caterpillar showing characteristic fuzziness. Pictures by Maria Cramer.

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