Vegetable IPM Update 08/11/21

Sweet Corn

European corn borer (ECB) moths have been captured at more locations over the past week, but numbers remain very low, and feeding has rarely risen to detectable levels.   ECB population maps will resume if second flight catches rise to high enough numbers.

The highest nightly blacklight trap catches of ECB for the week ending 08/11/21 are as follows:

Corn earworm (CEW) moth captures from both trap types are indicating a modest increase in overall population.  In general, blacklight trap catches are low but rising, and pheromone trap captures are increasing northward through NJ.    It should be noted that while many of these recorded catches are low for August, we do expect a significant increase in CEW activity at any time now through September.  Elevated pheromone catches remain at a few sites in Burlington, Gloucester and Atlantic counties.  Check this publication weekly for CEW status.  The number of pheromone traps deployed is much lower, resulting in much broader color bands on the map. It is also important to understand that pheromone traps are more sensitive than blacklight traps, and thresholds are adjusted to account for the higher catches typical of this trap type.  Silking  corn is at high risk of CEW infestation at this time.  On the blacklight map (left), green areas represent a 3-4 day silk spray schedule and blue represents a 4-5 day schedule.  On the pheromone map (below right), red represents a 3 day spray schedule, green represents a 4-5 day schedule, and blue represents a 5-6 day schedule. 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 08/11/21 are as follows:

The highest nightly pheromone trap catches of CEW for the week ending 08/11/21 are as follows:

Silking Spray Schedules*:
South – 3-4 days

Central –  4 days

North – 4-5 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.  Utilize materials in IRAC groups 5 and 28, or combination products that include IRAC group 28 for best control.  See the Sweet Corn section of the 2020-21 Commercial Vegetable Production Guide for selections.

Fall armyworm (FAW) larval infestations are becoming more common, particularly in coastal areas.  Threshold levels are being detected regularly in Monmouth and Ocean counties.  Injury from newly hatched larvae shows up as “window panes” or areas where leaf tissue has been eaten down the the lower epidermis (see photo at far left).  This injury leads down into the whorl.  As larvae gain size, they begin to consume leaf tissue in its’ entirety, creating ragged holes and lots of droppings (see photo at near left).  FAW can be tough to manage because it is resistant to synthetic pyrethroid insecticides (IRAC 3A) and because larvae are often covered by their own droppings, making contact with the insecticide more difficult.  Treat when 12% or more plants exhibit FAW injury alone, or in combination with ECB injury.  As a rule, insecticides that are most effective on CEW will also adequately control FAW.

Northern corn leaf blight (NCLB) is now appearing in more fields throughout northern NJ (see photo at left).  This fungal disease can increase in severity with longer dew periods that typically occur in August-September.  Lesions may form on husks, making them unsightly.  Heavy infections can result in reduced ear size.  When scouting, note the presence of these lesions, particularly if they first appear in whorl stage sweet corn.  Fungicides may be required to limit infections.  Useful materials include fungicides in FRAC codes 3,7 and 11, and may be found in the Sweet Corn section of the 2020-21 Commercial Vegetable Recommendations.

Tomatoes

Two-spotted spider mite (TSSM) infestations are increasingly 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 2020-21 Commercial Veg. Recs. for details on effective materials.

Brown stinkbugs (Euschistus spp.), and the injury they cause are becoming more common occurrences in tomato plantings.  These true bugs (see photo of Euschistus sp. nymph below at left), move into irrigated tomato fields as forage in the surrounding environment becomes less favorable.  Feeding results in “cloudy spot” (see photo at right below).  Increases in stink bug injury are often found by crews picking the fruit.  Growers should consider 1-2 insecticide applications to limit fruit injury if this damage is increasing in harvested fruit.  If actively scouting fields, insecticides should be considered if stink bug adults, nymphs or new fruit injury is found in 2 or more sample sites in a 10 site sample.  Insecticides that are effective on stink bugs include pyrethroids and neonicotinoids, so care should be taken to avoid contact with foraging bees.

Peppers

Pepper weevil – Traps are deployed, and we have still captured no weevils in pheromone traps.  We are not aware of any fields having infestations. We normally find the most infestations in August.  That we haven’t trapped any weevils is a good thing.  A new fact sheet is now available for anyone interested in monitoring for pepper weevils on their own:  FS1330: Monitoring and Management of Pepper Weevil in New Jersey (Rutgers NJAES).

Beet armyworm (BAW) captures have increased in southern NJ pheromone traps, although by historical standards the numbers are fairly low.  This pest can attack peppers, and growers and scouts should check for the presence of heavily damaged leaves near terminal growth on pepper plants.  BAW larvae will be found in the area of damage.  As yet, no injury has been reported.

The highest nightly pheromone trap catches of BAW for the week ending 08/11/21 are as follows:

Pumpkins and Winter Squash

Cucurbit downy mildew (CDM) is active on cucumbers in all parts of the state.  As yet, other cucurbits, including pumpkins, butternut squash, acorn squash and watermelons are unaffected.    For regional information on this important disease, see the Cucurbit Downy Mildew Forecast webpage:  http://cdm.ipmpipe.org/.    This forecast has  NJ at low risk of further infection as a result of transport events through Tuesday 8/10.  Note however, that active infections will persist and increase locally with repeated rain and heavy dew events.  It is advisable that all growers treat preventively for CDM on cucumbers and muskmelons.  As yet, there have been no reports in the region of CDM affecting any other cucurbit crops.  This is important, as pumpkins and winter squash are now active crops in the region.

Pumpkin fields in the scouting program have now nearly all exceeded powdery mildew (PM) thresholds (2 lesions/100 older leaves), initiating the PM spray program.  Lesions formed by this disease are shown in the photo (right).   For a list of effective materials and fungicide rotations, see the Pumpkin/Winter Squash section of the 2020-21 Commercial Veg. Recs.

Brown marmorated stink bug (BMSB)

BMSB blacklight trap catches have increased to a significant extent over the past week.  While these numbers are not alarming, they are an indication that adults are active and may be moving into host crops.  BMSB has not been a serious pest of peppers since 2011-12, but remains an important pest in orchards.  The highest activity is currently in Hunterdon and Salem County areas (see blacklight map at left).

The highest nightly blacklght trap catches of BMSB for the week ending 08/11/21 are as follows: