Sweet Corn

Corn earworm (CEW) moth captures have declined dramatically with cold night temperatures.  As nights warm again toward the weekend, we may see some recovery in adult activity.  Growers should consider this pest to still be at moderately high population levels in the state unless warmer nights indicate that the threat has diminished.     The current population poses a significant risk to silking corn.  Green areas on this map (see map at left)   represent a 3-day spray schedule.  However, night temperatures in the 40 to low 50 F range, may permit the extension of that spray interval by a day.  For further information on CEW activity, see pheromone trap information below.

The highest nightly trap catches of CEW in black light traps for the week ending 9/23/20 are as follows:

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Sweet Corn

Fall armyworm (FAW) larval infestations remain at low levels in the few remaining sweet corn plantings not yet silking.  At this point in the season, FAW shouldn’t become a widespread economic problem.  However, growers should be alert to the possibility of infestations on the last of their late plantings.   Injury from newly hatched larvae shows up as “window panes” or areas where leaf tissue has been eaten down the the lower epidermis. 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.  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.

Corn earworm (CEW) moth captures continued a gradual decline over this past week due to several nights with low temperatures.  The decline is less noticeable in the northern counties, where CEW blacklight catches had been quite high prior to the onset of cooler weather.  Therefore the weekly averages there are higher.  Overall, these catches are representative of lower adult activity, and growers should consider this pest to still be at moderately high population levels in the state.     The current population poses a significant risk to silking corn.  The reduction in CEW catch was not enough to substantially change this weeks map from last week (see map at left).  Green areas on this map representing a 3-day spray schedule.  For further information on CEW activity, see pheromone trap information below.

The highest nightly trap catches of CEW in black light traps for the week ending 9/16/20 are as follows:

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Sweet Corn

European corn borer (ECB) adults continue to be very low, and no map will appear in this edition.

Fall armyworm (FAW) larval infestations are at fairly low levels.  Infestations generally are in the single digits to below 20%, and with few plantings in the whorl stage at this point in the season, FAW shouldn’t become a widespread economic problem.  However, growers should be alert to the possibility of infestations on the last of their late plantings.   Injury from newly hatched larvae shows up as “window panes” or areas where leaf tissue has been eaten down the the lower epidermis. 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.  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.

Corn earworm (CEW) moth captures have decreased slightly over the past week.  This is likely due to several nights with temperatures dropping into the low 60s and even 50s F.  The decline is representative of lower adult activity, and growers should consider this pest to still be at moderately high population levels in the state.     The current population poses a significant risk to silking corn.  The reduction in CEW catch was not enough to substantially change this weeks map from last week (see map at left).  Green areas on this map representing a 3-day spray schedule.  For further information on CEW activity, see pheromone trap information below.

The highest nightly trap catches of CEW in black light traps for the week ending 9/09/20 are as follows:

[Read more…]