Sweet Corn

European corn borer (ECB) moth captures have increased in northern and central county light traps.  Numbers are low, as they have been in recent years, and no feeding has been detected on whorl and pre-tassel stage sweet corn as far south as northern Burlington County.  Whorl corn is the primary target for egg laying.  If the peak of the first flight is late, it sometimes results in heavier infestations on 2nd and 3rd plantings than on the first.  Feeding may be present in the southern counties, and should rise over the next 3 weeks.

Look for the characteristic “shot-hole” type of feeding (photo below at right) and consider treating when infested plants exceed 12% in a 50 plant sample.  As plantings proceed to the pre-tassel stage, ECB larvae may be found in emerging tassels (see photo at left).  It is a good idea to treat individual plantings as they move into the full tassel/first silk stage one time.  This eliminates any ECB larvae that have emerged with the tassels as they begin to move down the stalk to re-enter near developing ears.

Useful insecticides for this particular application include synthetic pyrethroids (IRAC Grp 3), spinosyns (including OMRI approved Entrust) IRAC Grp 5), and diamides such as Coragen or Vantacor (IRAC Grp 28) or materials such as Besiege which include the active ingredient in Coragen.  It should be noted that Coragen or Vantacor, used alone, are not toxic to bees that may be visiting corn tassels during this stage.  Synthetic pyrethroids alone should NOT be used for corn earworm (CEW) protection on silking corn.  Control with these materials is very inconsistent.

The highest nightly trap catches of ECB for the week ending 5/29/24 are as follows:

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Sweet Corn

A few scattered European corn borer (ECB) moths have been captured in central and northern counties, and this insect is certainly active in southern parts of the state.  Numbers are very low, which is consistent with the last few seasons.   Whorl corn is the primary target for egg laying, but as yet, scouts have reported no signs of feeding injury in the few plantings that are of suitable maturity.  In northern and central counties, corn plantings that were started on/under plastic have reached a size that will support ECB larvae.  We expect to encounter some level of feeding over the next 2-3 weeks, although the majority of plantings have not required insecticide treatments for ECB prior to full tassel in the past several years.

Look for the characteristic “shot-hole” type of feeding (photo below at right) and consider treating when infested plants exceed 12% in a 50 plant sample.  As plantings proceed to the pre-tassel stage, ECB larvae may be found in emerging tassels (see photo at left).  It is a good idea to treat individual plantings as they move into the full tassel/first silk stage one time.  This eliminates any ECB larvae that have emerged with the tassels as they begin to move down the stalk to re-enter near developing ears.

Useful insecticides for this particular application include synthetic pyrethroids (IRAC Grp 3), spinosyns (including OMRI approved Entrust) IRAC Grp 5), and diamides such as Coragen or Vantacor (IRAC Grp 28) or materials such as Besiege which include the active ingredient in Coragen.  Synthetic pyrethroids alone should NOT be used for corn earworm (CEW) protection on silking corn.  Control with these materials is very inconsistent.

The highest nightly trap catches* of ECB for the week ending 5/22/24 are as follows:

*  No blacklight traps are in operation south of the Columbus (Burlington Co.) area this season.

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Sweet Corn

IPM personnel have deployed black light and corn earworm (CEW) pheromone trap networks in central and northern New Jersey counties.  As we start our summer field technicians, trap checks are limited.  However, even with cool weather and few traps visited, there have been low catches of CEW in several pheromone traps.  While this is of little consequence now, it does suggest that local overwintering is a possibility.   We have experienced increasing CEW populations in recent years at the time our early plantings silk (mid-June), and the presence of moths in early May points to more of the same this year.

Black light trap derived maps for European corn borer (ECB), CEW and brown marmorated stink bug (BMSB) will not appear in the Plant and Pest Advisory, as there is no statewide blacklight trap network.  Data from existing black lights in the central and northern counties will appear in table format, with associated information on the relevance of the populations.  Provided that  data from the southern CEW pheromone traps is available on a regular basis, maps will be generated for this pest/trap type.   Limited collections from traps thus far have not contained any target pests.

Slugs

With recent cool wet weather, slug damage (photo at left, by J. Compton) to various crops, including sweet corn has begun to appear.  No till or zone till situations give slugs ample hiding places under the surface layer of debris.  Plastic mulch can also protect slugs as long as weather remains cool.  They are largely active at night but can be found on crop plants anytime conditions are very wet.  Most slugs are not as large as the specimen in the picture at right, but even small garden slugs can do significant damage to seedlings.  Be sure to monitor fields during wet and cool conditions.  The presence of slugs and their damage may require an application of slug bait to the affected areas.  Various slug baits are available, but labels should be consulted to determine which product is permissible on the affected crop.  Check the Pest Management section in the 2024 Commercial Vegetable Production Guide for products.

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Sweet Corn

IPM personnel have deployed black light and corn earworm (CEW) pheromone trap networks in central and northern New Jersey counties.  In areas from central Burlington County southward, grower cooperators have been provided with CEW pheromone traps and will be monitoring these traps on their own properties and reporting catch data to IPM personnel.  This is an effort to maintain a statewide reporting program for the most significant economic pest of sweet corn despite a shortage of professional staff this year.  The IPM program thanks these growers in the southern counties for their assistance in maintaining this necessary service.

Black light trap derived maps for European corn borer (ECB), CEW and brown marmorated stink bug (BMSB) will not appear in the Plant and Pest Advisory, as there is no statewide blacklight trap network.  Data from existing black lights in the central and northern counties will appear in table format, with associated information on the relevance of the populations.  Provided that  data from the southern CEW pheromone traps is available on a regular basis, maps will be generated for this pest/trap type.   Limited collections from traps thus far have not contained any target pests.

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