The system and method automatically controls the position of at least one deck plate (28) of a harvesting unit (24) of a corn header (22) so as to increase the width (W) of a stalk receiving channel (30) or reduce pinching forces between the plates (26, 28) when entering a stand of corn to facilitate alignment with the corn rows, and to change the position after a suitable time period or other condition or event, to narrow the channel width (W) and/or increase pinching force, to reduce kernel loss while also monitoring forces exerted against the plates (26, 28) by the stalks and responsively adjusting the plate position for maintaining a desired force on the stalks (32) or width (W).
