Twenty-one sites reporting this week. Only three sites caught European corn borer (ECB)-E and two sites caught ECB-Z. Only one ECB hybrid was caught this week at the Seneca Castle site. Corn earworm was caught at seven sites with six sites high enough to be on a 5 or 6 day spray schedule (see table below). Still no fall armyworm (FAW) or western bean cutworm (WBC) caught this season.

I found more ECB larvae in whorl stage corn this week even though trap catch numbers over the last few weeks were fairly low. When scouting focus on the emerging tassel. Separate the leaves and look down into the tassel for any signs of feeding, frass or larvae. The threshold for ECB is 15% infested plants at tassel emergence. Larvae feeding in the whorl are protected from insecticide applications and mortality will not be as high as at tassel emergence, when larvae feeding in the emerging tassel are exposed to the spray. Larvae will leave the tassel as it opens up and no longer provides a moist, protected feeding environment, and move down the plant looking for protected places to feed. Insecticide applications need to be timed to kill larvae before they bore into a new feeding location where again they will be protected from sprays (see photos below for tassel stages). In fields with very uneven development, two applications may be necessary, one when approximately 25-50% of the tassels have emerged, and again after 75-100% of the tassels have emerged, if the field is still over threshold.