higgledy wrote:
To save
the cost of buying planting tubers or seed, can I use the potatoes from
the local supermarket? Have they been rendered sterile?

Taters from the market have typically been treated with a chemical that
inhibits sprouting. If you buy organic taters, though, they should
sprout.

Potatoes have viruses which collect in the tubers and decrease vigor
with each generation. These viruses are transmitted through aphids.
Certified "seed" are free of these viruses. If you grow out
store-bought taters or those you grew yourself you may have more and
more of these viruses with each generation and less and less vigor.
this will depend on the presence of aphids.

These viruses accumulate over time when taters are grown from
non-certified seed. Certified "seed" can be grown in areas that are
free from aphids. This is in locations way up north or at high
altitude. The ancestral home of the potatoe is the high altitude
region of Peru and Ecuador.

Other certified "seed" is grown out in sterile culture (petri dishes)
in a labratory in order to eliminate the viruses. This is how seed is
certified and is why you might want to grow certified seed. Of course
a lot of folks grow from saved tubers. results The qulity of your crop
just may not neccesarily be consistent with the tubers that were
planted. The decline in vigor may be a lot or it may be none. This
depend on the presence of aphids during the grow out. You can use a
landscape fabric like "Remay" to exclude aphids from yur spuds.

In short, it is best to buy certified. If you want to grow a rare
strain then certified may not be available. Next best is to grow out
uncertified tubers that you produced yourself in which case you will
have a better selection of varieties. After that, you might grow out
some organically grown spuds which will be free of anti-sprouting
chemicals. Lastly, supermarket taters are unsuitable for planting and
should be tried only as an experiment and not if you are counting on a
crop.