Note: Next week (10/07/20) will be the final regular edition of the Vegetable IPM Update for 2020. We will post alerts should special pest situations arise.
Sweet Corn
Corn earworm (CEW) moth captures continue to decline, although with temporary increases on warm nights. Growers should consider this pest to still be at moderate population levels in the state, with higher risk during stretches of warmer nights. The current population poses a significant risk to silking corn. Green areas on this map (see map at left) represent a 3-day spray schedule. However, night temperatures in the 40 to low 50 F range, may permit the extension of that spray interval by a day. For further information on CEW activity, see pheromone trap information below.
The highest nightly trap catches of CEW in black light traps for the week ending 9/30/20 are as follows:
| Hackettstown 3 | Eldora 2 | Matawan 1 |
| Allamuchy 2 | Sergeantsville 2 | Medford 1 |
| Bellemeade 2 | Califon 1 | Oldwick 1 |
| Clinton 2 | Downer 1 | South Branch 1 |
A similar temperature-based reduction in CEW pheromone catch occurred this past week (see CEW pheromone map at left). The blacklight network is still indicating a 3-day silk spray schedule in the northern counties, while the pheromone network is at 5-6 day. Under cold night conditions, it is possible to adhere to the more relaxed schedule, but growers should tighten up by a day if we return to warmer nights. The number of pheromone traps deployed is much lower, resulting in much broader color bands on the map. Additionally, several of the northern pheromone trap sites no longer have silking corn nearby. This influences the catch, resulting in fewer moths captured. The current population continues to be an economic threat. It is important to use effective materials to manage this pest on silking corn. Insecticides in the IRAC 28 class (Coragen, Besiege, Exirel) and IRAC 5 (Radiant, Blackhawk, Entrust (OMRI approved)) remain among the most useful insecticides against CEW.
The highest nightly trap catches of CEW in pheromone traps for the week ending 9/30/20 are as follows:
| Green Creek 31 | Berlin 10 | Allamuchy 1 |
| Pedricktown 20 | Springdale 7 | Dayton 1 |
| Eldora 12 | South Branch 2 | Matawan 1 |
Silking Spray Schedules*:
South – 3-4 days
Central – 3-4 days
North – 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.
Pumpkins and Winter Squash
Melon aphid (see photo at left) populations may be present in pumpkin and winter squash fields. This aphid builds to heavy populations 
that result in the deposition of sticky droppings on the surface of fruit (see photo at right). If melon aphids appear in more than one sample site in a 10 site sample, consider treating to minimize the appearance of droppings. Insecticides effective at managing this pest are found in the Pumpkin and Winter Squash section of the Commercial Vegetable Production Recommendations.
Cole Crops
Fall plantings of cole crops are well underway at this time, and are frequently infested by imported cabbageworm (ICW) and diamondback moth (DBM) larvae. At this time, cabbage looper (CL-photo at left) and cross striped cabbage worm (CSCW-photo at right) are also causing
injury to these crops.
Check 5 consecutive plants each in 10 random locations throughout the planting. Consider treating if caterpillars are found on 10% or more plants that are in the 0-9 true leaf stage. From 9-leaf to the early head stage (in broccoli, cauliflower, and cabbage) infestations up to 20% may be tolerated. Once heads begin to form, a 5% threshold should be observed to protect the marketable portion of the plant. For leafy greens such as collards and kale, 10% plants infested is the threshold throughout.
Some populations of DBM are resistant to carbamate and synthetic pyrethroid insecticides. The lack of DBM control with these insecticides has been noted in NJ previously. It is important to distinguish between common cole crop pests for this reason. DBM larvae grow to a length of approximately 0.5”, and taper toward both ends (see photo at right). These caterpillars thrash violently when disturbed. Newer chemistries that specifically target caterpillar pests are effective against DBM as well as all other caterpillar pests of cole crops, including beet armyworm (BAW-see photo at right), another species with exhibiting pyrethroid resistance. These materials include (active ingredient – trade name (IRAC* code)):
Spinosad/Spinetoram – Entrust(OMRI)/ Radiant (5)
Chlorantraniliprole – Coragen (28)
Cyantraniliprole – Exirel (28)
Crucifer downy mildew has been detected on collards recently. While all cole crops are hosts, collards are frequently the most heavily affected. Crucifer downy mildew results in small dark lesions with yellow borders on the upper leaf surface. On the lower leaf surface, whitish sporulation is often present (see photo at left). Preventive fungicide applications are advisable for this disease. For control materials, see the Cole Crop Section of the 2020 Commercial Vegetable Recommendations.
Spinach, beets and chard
Hawaiian beet webworm on spinach
Hawaiian beet webworm (HBWW) moths have been detected on central and southern NJ farms. Thus far, these moths have been seen in weedy areas of non-host crops. The moths are quite numerous where they have been found. Farmers with spinach, beets, and chard should check their fields for the presence of webbing and feeding injury. These are small migratory moths usually occurring in mid-to-late summer. Their favored host is the pigweed, Amaranthus sp., but they are capable of causing defoliation and contamination to crops. Since they are migratory and have a short life cycle they can rapidly appear and cause extensive damage to crops unnoticed.
Allium Leafminer
It is allium leafminer (ALM) season again, and growers of leeks, scallions, etc. should be protecting crops either with row covers, or with labeled insecticide appliations targeting adults. See photo at right, of adult egg-laying scars on scallion leaves. Spinosyn materials (Radiant, Entrust (OMRI approved)), pyrethroids (Mustang Maxx, Warrior), neonicotinoids (Scorpion, Venom) and the insect growth regulator Trigard are labeled for miner control. The diamide, Exirel, is permitted in NJ under a 2ee label as well.
