European corn borer (ECB) moth activity is slowly increasing and spreading northward (see ECB map) . This is the early part of the second flight. Very few larval infestations have been detected. Be sure to begin monitoring plantings for ECB feeding while they are still in the whorl stage. Consider treating when the number of infested plants in a 50 plant sample exceeds 12%. Feeding in the whorl stage will appear as numerous small holes (called “shot-hole”) on leaves, with damage present on consecutively younger leaves. As plants progress to pre-tassel and beyond, droppings and larvae may be found in or on the emerging tassels. Any planting remaining at or above threshold as it proceeds to full tassel should be treated, as this is the last stage at which ECB larvae will be exposed and vulnerable to insecticidal sprays. Insecticides that are acceptable in organic production include the spinosyn based material Entrust (IRAC-5) and Dipel (IRAC-11a). The 10G formulation of Dipel is particularly useful when granules can be dropped or broadcast such that they get into the whorls of corn plants. Other effective insecticides include Coragen (IRAC 28), and the synthetic pyrethroids (IRAC 3). See the 2016 Commercial Vegetable Recommendations Guide for a more complete list of insecticides.
The highest nightly ECB catches for the previous week are as follows:
|Denville 3||Flanders 1||Long Valley 1|
|Eldora 2||Georgetown 1||New Egypt 1|
|Allentown 1||Jones Island 1||Old Bridge 1|
|Beckett 1||Lawrenceville 1||Sparta 1|
Infestations of fall armyworm (FAW) are stable in much of the state, but in Cape May County, infestations above 40% have been reported. It is often the case that FAW infestations are heavier in coastal areas. A number of infestations are above threshold, with small whorl stage plants most frequently impacted. FAW targets whorl corn of all sizes, and even very young plants should be checked weekly. FAW feeding is much more obvious than that of ECB larvae, with large ragged holes and conspicuous droppings found in the whorl. The larva is larger, and is general brown in color after it has molted twice (see photo at left). It is useful to note that FAW is less susceptible to the B.t. toxin found in older B.t. sweet corn lines. Therefore some FAW injury can still occur from seedling stage through ear development. FAW is also resistant to synthetic pyrethroid insecticides (IRAC 3), but can be effectively managed with insecticides such as Radiant/Entrust/Blackhawk (IRAC 5) or Coragen/Besiege (IRAC 28). Consider treating if damage from ECB and/or FAW reaches 12%.
Corn earworm moth (CEW) captures in blacklights remain low, but more individuals have appeared in central county traps this past week. CEW catches have spiked sharply in North Carolina traps, but this has not the case in Virginia and Delaware. Generally, as CEW moths increase to our south, we can anticipate some influx of moths in NJ should southerly winds dominate for several days, or a low pressure system comes up the coast. For the immediate future, such a migratory influx appears unlikely. Highest activity remains across the southern third of NJ (see CEW blacklight map).
The highest nightly CEW catches for the previous week are as follows:
|Centerton 1||Farmingdale 1||Jones Island 1|
|Cinnaminson 1||Folsom 1||Milltown 1|
|East Vineland 1||Georgetown 1||Pedricktown 1|
|Eldora 1||Green Creek 1||Woodstown 1|
In addition, a limited number of CEW pheromone traps have been deployed throughout the southern counties. These traps are capturing steady, low numbers of CEW moths. Highest activity from this network has been found from Gloucester into Atlantic and Camden counties (see CEW pheromone map). The broad color patterns of this map are a result of the few numbers of contributing trap sites. Green areas on the map roughly correspond to a 4-5 day silk spray schedule. As sweet corn plantings begin to silk, it is critical that growers monitor local CEW moth numbers. For the present time, any sweet corn plantings in the silk stage should be treated to limit CEW injury as well as to prevent ear damage from ECB larvae that already inhabit the stalks.
The highest nightly CEW pheromone trap catches for the previous week are as follows:
|Monroeville 10||Green Creek 5||East Vineland 2|
|Berlin 8||Woodstown 5|
|Elm 7||Jobstown 4|
For silking sweet corn, the following spray schedules are warranted.
Silking Spray Schedules*:
South – 4-5 days
Central – 5-6 days
North – 6 days
*These recommendations are based on regional catches.
BMSB captures in NJ blacklight traps have declined somewhat over the past week. The highest activity is currently in the southern third of the state (see BMSB map). At the present time, BMSB numbers remain well below those seen in 2010-12. However, this increase will be monitored and incidents of injury from this pest will be documented. BMSB can be a pest on peppers, as well as sweet corn and beans. As yet, no individuals have been spotted in scouted peppers.
The highest nightly BMSB trap catches for the previous week are as follows:
|Centerton 6||Farmingdale 2||Georgetown 1|
|Green Creek 5||Matawan 2||Hackettstown 1|
|Beckett 3||Crosswicks 1||Newton 1|
|Eldora 3||Downer 1||Pedricktown 1|
Pumpkins and Winter Squash
These crops are now mostly in bloom stage. Cucumber beetles are less of a threat at this stage, as the plants have attained enough size to avoid developing bacterial wilt from new beetle feeding.
As scouted pumpkin and winter squash fields begin to develop fruit, we are beginning to see the first powdery mildew (PM) lesions develop. The action threshold for commencement of the protectant fungicide program for PM is 2 lesions per 100 older leaves. The most mature fields in the IPM Program are just experiencing fruit enlargement; the stage at which first PM lesions often occur. See the 2016 Commercial Vegetable Recommendations Guide for a list of appropriate protectant fungicide rotations for PM control.
A sentinel plot containing susceptible and resistant cucumber varieties, as well as muskmelons, watermelons, acorn and butternut squash and pumpkins is now established at the Snyder Research and Extension Farm in Hunterdon County. The purpose of this plot is to detect the presence of downy mildew (DM) in northern NJ. As of July 27, DM HAS BEEN DETECTED on the susceptible cucumber variety ‘Straight 8’. No other crops in the sentinel plot are infected, including the resistant cucumber variety SV 3462 from Seminis. Rains forecast for late this week could make conditions more favorable for disease development, so all growers should be applying appropriate protectant fungicides plus DM specific materials to cucumbers at this time. DM lesions appear as yellow areas on the upper leaf surface with leaf veins making distinct borders to the lesions (see photos above). On the lower leaf surface, beneath the lesions, dark spores may be seen if conditions are moist. For more information on the regional presence of DM as well as comprehensive, weekly forecasts, see the following website: http://cdm.ipmpipe.org/
Native brown stink bugs (see photo at right), eggs and damage have all been observed in a NJ pepper and tomato fields this week. The appearance of this pest in peppers and tomatoes follows increased catches of all stinkbugs in recent weeks. July is the month when injury typically increases, and the presence of stink bugs in a planting is often detected by the appearance of damaged fruit rather than the discovery of actual bugs. Damage, called “cloudy spot” of often pale green on green pepper and tomato fruit. It is often best to approach sample sites slowly while scouting. Stink bugs will often bask in the sun near the tops of plants, but will quickly descend into the canopy when approached. Consider treating if brown sink bugs are found in more than one sample site in 10, or the presence of feeding on harvested fruit is increasing. See the 2016 Commercial Vegetable Recommendations Guide for a insecticides useful in the control of stink bugs.
In addition, several plantings have developed thrips populations. Feeding from these pests on fruit results in a superficial “gold flecking” on the surface of ripening fruit. Heavy feeding may make fruit unmarketable. Often, thrips will feed on foliage before moving to fruit. Foliar feeding results in cleared areas on the leaves with dark specks (droppings) associated with the damage (see photos at right). These pests are tough to manage, because their small size and habit of residing in flowers and beneath the calyx on fruit makes contact with insecticides difficult. Get thorough coverage and do not wait for large populations to develop before treating. While scouting for other pests and diseases, not the presence of foliar and fruit injury. If either begin to appear in multiple samples of a 10 site sample, consider treating to minimize fruit injury. See the 2016 Commercial Vegetable Recommendations Guide for a insecticides useful in the control of thrips.
As the summer advances, tomato fruit damage from CEW (fruitworm) will become more common. Damage is often on green fruit (see photo at left) nearest the top of the plant. If fruit injury is increasing, and CEW trap catches indicate steady populations in the area, insecticide applications may be warranted. Insecticides in the IRAC Grp. 5 (Radiant, Entrust) and IRAC Grp. 28 (Coragen, Exirel) are preferable for caterpillar control on fruiting crops as they have minimal impact on beneficial insects that help control aphids.
No weevils were trapped this week. As far as known, there are no infested fields at this time.