A system processes seeds that are present in crop material. The system includes a first shearing surface, a second shearing surface arranged opposite the first shearing surface, and a clearance between the first shearing surface and the second shearing surface. The system passes crop material between the first and second shearing surfaces, where the crop material contacts the shearing surfaces as it passes through the shearing surfaces. Contact with the first and second shearing surfaces damages seeds that are present in the crop material. The system can be installed in a combine harvester to damage seeds that are present in crop residue to prevent the seeds from germinating after the crop residue is discharged from the combine harvester back into the field.