Barrier crops and isolation distances are important factors in protecting crops against insects and diseases and are therefore important in sweetpotato quality declared seed (QDS) systems. For example, it is advisable, though not always possible, to try to separate new sweetpotato fields from recently harvested or existing fields, particularly in environments where weevils and viruses are a problem. A barrier crop between old and new plants or a gap of >120 m can help prevent weevils from reaching the new crop.