For those of you with late plantings of sweet corn or field corn that is still in the late stages of silking, do not let your guard down! We are still recording high trap catches throughout the state. Almost every reporting location (except for the Purdue Student Farm) is catching a nightly average of moths exceeding the action threshold of 10 moths per night. It is no time to skip an insecticide application, despite how alluring that may be this time in the season when we are all growing weary of long days in the field. We may even be seeing record trap catches during my time managing this monitoring network, with our research farm in Tippecanoe County capturing 1,268 over the weekend (an average of 422 per night!). Be sure you are sticking with a rotation in the application of your products. While I have not had any direct reports, some of my colleagues in other states monitoring the resistance of CEW to pyrethroids begin to see this creep into the population late in the season. As always, you can keep an eye on our trapping network by clicking here. And, in case you have forgotten, below are some photos of the variation found in the caterpillars (Figure 1) and the adult moth (Figure 2).
Figure 1. Corn earworm caterpillar variation in color (Photo by John Obermeyer).
Figure 2. Corn earworm adult, wings expanded, over corn silks (Photo by John Obermeyer).