Tuber-unit planting is a tool that has been used to improve the effectiveness of the roguing process. All
seed pieces cut from a single tuber are manually fed into a planting mechanism, which places them
consecutively in a row. A gap is sometimes left between the seed pieces generated from different tubers. If
the plants originating from any of the seed pieces cut from a single tuber express symptoms of disease, then
all the seed pieces cut from the tuber are removed from the field. This ensures that all seed is removed
from the field even if only one piece is manifesting symptoms of disease or has characteristics of a foreign
variety. Since tuber-unit planting is slow and very labour intensive, its use is limited to small plots of high
value seed. This practice was a regulatory requirement for the first and second field generations of seed.
Regulatory amendments approved in May 2002, resulted in the removal of this requirement from seed
regulations, due to cost, and time consideration, relative to industry benefits. However, it is considered an
important management tool for seed growers, particularly when a grower has concerns for the level of virus
that may be present in seed planted.