Sweet Corn
Fall armyworm (FAW) infestations remain present, although in fields where growers responded with appropriate insecticides, control has been good. Because FAW moths are highly mobile, it is important to monitor fields at least weekly for signs of infestation. Whorl stage plants are prime targets for egg laying.
Newly hatched FAW larvae cause holes and scratches on leaves that are similar to ECB feeding, except that they tend to be more concentrated and always lead down into the whorl (see photo at left). As the larvae grow, the feeding becomes more destructive, with large ragged holes and obvious droppings deposited in the whorl (see photo at right). 
We will provide updates on new FAW appearances and severity as reports come in. FAW are resistant to synthetic pyrethroids. Effective sprays should include IRAC grp. 5 (spinosyns) or IRAC grp. 28 (diamides). The carbamate (IRAC grp. 1A) Lannate is also still effective. Sufficient water should be used in the applications to allow the solution to penetrate the layer of droppings that may have formed above the caterpillar.
Corn earworm (CEW) moths captures from northern and central blacklight traps are increasing now, with more sites registering catches. Pheromone trap information is available from all northern and central sites, but is limited from southern New Jersey. Overall, pheromone catches are also rising. Tabernacle (Burlington), New Egypt (Ocean) and South Branch (Somerset) locations had the highest activity this week, but pheromone catches overall were higher (see pheromone trap may below). We should expect this trend to continue, with very large migratory events occurring any time strong southerly winds/low pressure permit. It is noteworthy that CEW trap catches have risen in North Carolina and Virginia just over the last week. 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 7/31/24 are as follows:
| Denville 5 | Bellemeade 2 | Califon 1 | Lawrenceville 1 |
| Farmingdale 5 | Morristown 2 | Dayton 1 | Milltown 1 |
| Matawan 3 | Allamuchy 1 | Hackettstown 1 | Sparta 1 |
The highest nightly pheromone trap catches of CEW for the week ending 7/31/24 are as follows:
| Tabernacle 61 | Farmingdale 19 | Matawan 15 |
| New Egypt 39 | Hackettstown 18 | Middle Valley 13 |
| South Branch 31 | Snyder Farm (Hunterdon) 18 | Allamuchy 12 |
| Bellemeade 26 | Dayton 17 | Woodstown 12 |
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 – 3-4 days
North – 3-4 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.
Growers experiencing problems with sap beetles during harvest should consider adding the active ingredient acetamiprid in 1-2 silk applications along with the CEW targeted materials. This IRAC group 4A material (Assail, Anarchy) will not control CEW, but is useful for sap beetles and corn leaf aphids. Hot days and warm nights favor sap beetle infestations, particularly when corn ears grow to the end of the husks, enabling easy entry for the beetles.
Field scouts are finding corn leaf aphid (photo at left) more often in pre-tassel and tassel stage sweet corn. This pest can build to very high numbers on plants, and with repeated use of pyrethroid insecticides, can become a contaminant as it infests corn ear husks. If aphids are detected in tassels just prior to silking, consider adding the neonicotinoid acetamiprid (Assail, Anarchy) to the regular silk spray material(s). Methomyl (Lannate) is also useful at limiting aphid populations.
Tomatoes
Thrips infestations continue in some fields. Hot weather can increase infestations. These
insects initially feed on foliage (see photo at right), and ultimately move to the surface of fruit, where they cause gold flecking to occur on ripening fruit (photo at left). While all “gold fleck” is not related to thrips, that which forms distinct rings and trails on fruit surfaces is caused by their feeding. Thrips can be difficult to manage due to insecticide resistance issues and their habit of hiding in blossoms and other tight spaces on the plants. It is best to apply control before populations become widespread in plantings. See the Tomato Section from the 2024-25 Guide for suggested insecticides.
Two-spotted spider mite (TSSM) infestations are common in scouted tomato plantings. These pests multiply rapidly, and can cause severe defoliation under high temperature conditions if not detected early. Look for leaflets exhibiting pin spots (left) on the upper surface. These leaflets will become yellow as TSSM numbers increase. Mites may be observed on the underside of leaves showing these signs. Extreme infestations will result in extensive webbing being produced on top of foliage (right). Treatment should be undertaken when mites are first detected, because larger established infestations are quite difficult to control. Spot treatments may be effective if the infestation is limited. See the Tomato Section of the 2024-25 Commercial Veg. Recs. for details on effective materials.
Beet Armyworm
Beet armyworm (BAW) numbers in pheromone traps in the Woodstown area of Salem County have increased dramatically over the past week. Thanks to a grower cooperator in that area, we know that catches are 119/night over the past week in local traps. This pest can cause significant injury on peppers as well as leafy greens like swiss chard. Monitor pepper fields weekly for signs of feeding. BAW larvae (photo at left) feed in the developing foliage in terminal growth of plants. Initially, leaves are skeletonized, but as larvae grow, they will move onto fruit and damage these as well. Extreme injury to swiss chard and
collards can occur very quickly (photo at right). 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 downy mildew (CDM) has been detected on cucumber in the sentinel plot at Snyder Research and Extension Farm in Pittstown, Hunterdon County as of 7/17/24. Additionally, a Morris County cooperator reports CDM on an abandoned cucumber plot near Chester. All cucumber growers should monitor fields for signs of this disease. Look for chlorotic areas bordered by veins on the upper leaf surface (photo at lower right). If conditions are moist, dark sporulation may be found on the lower leaf surface (photo at lower left).
All cucumber and cantaloupe plantings should be protected. Useful materials for CDM may be found in the Cucumber Section of the 2024/25 Commercial Vegetable Production Recommendations. A sentinel plot has been established at Snyder Farm in Hunterdon County. This plot consists of pumpkin, watermelon, cantaloupe, butternut, acorn, cucumber and kabocha squash will be used to indicate the presence of cucurbit downy mildew in the region, and what crops are affected. As of 7/22/24, CDM had not been detected on any of these crops except cucumber in the sentinel plot, nor has CDM been found on any scouted field in northern and central NJ except cucumber.
Powdery mildew (PM) thresholds (2 infected leaves/50 leaf sample) have been reached in a number of scouted plantings over the past week. PM typically does not appear until a significant fruit load develops on host plants. Once PM lesions (photo at right) begin to appear, the protectant fungicide program for this disease should be initiated. The program generally includes a combination of broad spectrum protectants and more targeted, locally systemic fungicides. For a complete list of suggested materials, see the Pumpkin and Winter Squash Section of the 2024/25 Commercial Vegetable Production Recommendations. Ideally, a fungicide program should include a rotation of 3 different FRAC code materials combined with broad spectrum protectants in each application.
Thank you!
The Vegetable IPM Program wishes to thank the following Field Technicians, without whom much of the information presented weekly here would not be available:
Chris Cloutier
Hamna Khalid
Alexandra Suszko
