Sweet Corn

European corn borer (ECB) moths catches have declined to very low levels over the past week and no map will appear in this edition.  The first flight is complete.  Feeding percentages have stabilized, and no new feeding should occur until the second flight arrives.

Growers should continue to scout whorl and pre-tassel stage plantings weekly 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.  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 (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 6/19/19 are as follows:

Scattered corn earworm (CEW) moths continue to be captured in southern NJ blacklight traps through early this week (see blacklight map at left) although these catches have declined since last week.   Early plantings, now silking, are at risk of infestation from this pest.

In the CEW pheromone trap network, catches have also declined but remain highly variable, with higher numbers in the south, and very low activity in northern NJ (see pheromone map  below at right). The green area on the pheromone trap map indicates a 4-5 day silk spray schedule. Blue areas represent a 5-6 day schedule, and white areas are 6-7 day.  There are far fewer CEW pheromone traps than blacklights, and the resulting map has much broader color bands as a result.  It should also be noted that the pheromone traps are much more sensitive than blacklights.  Therefore, the number of moths caught in pheromone traps required to generate a specific spray interval is much higher than the number caught in blacklight traps.   It must be stressed that there is high variability in these catches, and growers should consult with their IPM practitioner on recommended spray schedules.

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Sweet Corn

European corn borer (ECB) moths catches have declined to nearly nothing over the past week (see map at left).  Feeding percentages have increased, and should peak over the next 5-7 days.  As of the weekend, feeding percentages as high as 24% in Cape May and 60% were found in whorl corn in Somerset County, but these numbers seem to be outliers. The majority of feeding is in the 2-14% range throughout much of the state.

Sweet corn emerging tassel with ECB droppings.
Photo: Kris Holmstrom

Growers should scout whorl and pre-tassel stage plantings weekly.  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 (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 6/12/19 are as follows:

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Sweet Corn

 European corn borer (ECB) moths catches have declined somewhat over the past week.  Overall this flight was very low, and appears to be on the way out.  The majority of moth activity at this time is along the Delaware Bay Shore (see map at left).  Feeding percentages should increase for the next 2 weeks, as eggs that have been deposited hatch.  As of this week, feeding percentages as high as 8-10% were found in whorl corn in Burlington County.  It is likely that feeding has exceeded the 12% threshold in many southern NJ plantings.

Sweet corn emerging tassel with ECB droppings.
Photo: Kris Holmstrom

Growers should scout whorl and pre-tassel stage plantings weekly.  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 (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 6/05/19 are as follows:

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