Sweet Corn

Warmer evening temperatures have resulted in modest increases in European corn borer (ECB) moth catches in blacklight traps in the northern and central counties.  Whorl corn is the primary target for egg laying, and injury over the 12% threshold has been found in Hunterdon County this week.  It is likely that there are pockets of feeding throughout the southern counties.  Despite relatively low numbers, this pest still poses a threat to plantings now approaching full tassel.  It is typical for feeding percentages to rise as the moth catch declines.  We expect feeding to increase for the next 1-2 weeks before peaking.

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 6/07/23 are as follows:

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Sweet Corn

Due to continued cold night temperatures, European corn borer (ECB) moth captures have been extremely low in northern and central county light traps.  Thus far this flight has been weak, and no feeding has been detected on whorl and pre-tassel stage sweet corn as far south as northern Burlington County.  An increase in nighttime temperatures (even temporarily) may result in somewhat higher numbers over the next week.   Whorl corn is the primary target for egg laying.  If the first flight is late rather than nonexistent, this sometimes results in heavier infestations on 2nd and 3rd plantings than on the first.  Feeding levels could be somewhat higher 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.  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 5/30/23 are as follows:

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Sweet Corn

Scattered European corn borer (ECB) moths are now being captured in central and northern counties, and this insect is certainly active in southern parts of the state.  Numbers are quite low.  It remains to be seen whether this first flight will amount to much, but recent years’ catches give no reason to suspect that a large population will develop.   Whorl corn is the primary target for egg laying, but as yet, scouts have reported no signs of feeding injury.  In northern and central counties, corn plantings that were started on/under plastic are now reaching a size that will support ECB larvae.  We expect to encounter some level of feeding over the next 2 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 5/24/23 are as follows:

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

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