A corn header for a combine harvester is described, the corn header comprising a plurality of harvesting units (10) whereby the harvesting units are configured to separate corn ears from corn stalks. Each of the harvesting unit (10) comprises a deck plate assembly (26, 28), and an actuator assembly (50) configured to adjust a width (W) of a stalk receiving channel (30) by adjusting a position of at least a deck plate of the deck plate assembly (26, 28).The corn header further comprises a kernel sensor (70) to generate a signal representative of the presence of kernels that are detached from the corn ears and a control unit (80) to receive the signal from the kernel sensor (70) and generate, based on the signal, an actuator control signal for controlling the actuator assemblies (50), thereby controlling the width (W) of the stalk receiving channels (30).
