With corn shooting up, some fields are not too far away from tasseling.  It is critical to scout all corn when the primary ear is growing and to protect it during the two weeks prior to tasseling.  This recent blog post details important changes to the threshold that were made this year and provides guidance on how to scout and spray.

Our threshold for this stage of corn growth is based on sampling only a small part of the plant and is relative to the position of the primary ear.  Furthermore, to properly use the threshold (and to prevent banana ear), the ear must be protected prior to tasseling and ear emergence.  Therefore, finding the primary ear is a necessary part of scouting.  Note that the location of the primary ear will depend on hybrid and environmental conditions.  So it’s important to note this for each field that’s scouted.

To find the primary ear, locate where on the plant you expect the primary ear to form and begin carefully removing leaves by pulling back the collars.  Except near the top of the plant, a small ear shoot should be visible behind each leaf.  These ear shoots will be smaller lower down in the plant.  Early in ear development, the top-most and largest of these ear shoots will begin to grow rapidly and, as the ear develops, you will be able to dissect it out of the ear shoot.  If you can identify this area of the plant, then you have located the primary ear.  If a secondary ear is forming, you will also notice ear shoot development in the node directly below the primary ear.