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:
Blairstown 1 | Princeton 1 |
Chester 1 | Sergeantsville 1 |
Morristown 1 | South Branch 1 |