Although roguing is considered to be a valuable tool in the maintenance of seed quality, it is rarely
completely effective. Only those plants that are manifesting visually recognizable symptoms can be
rogued. Symptom expression can be influenced by many factors including environmental conditions and
varietal characteristics. In addition, not all pathogen-infected plants (even those from seed pieces cut from
the same tuber) express disease symptoms to the same degree or at the same stage of growth. The end result
is that much of the roguing is conducted to provide a visually clean field that will satisfy the seed
certification specifications.