"Martin Brown" wrote in message
...
In message , Annabel
writes
I thought nicotine was a contact insecticide. I didn't know it was
also systemic. But it does bio-degrade quite rapidly apparently, so
it
would soon break down when watered onto the soil or even if tobacco
leaves or cigarette butts were composted.

I picked up about nicotine being systemic in plants on some web site
but
I do not know if it's true. It is systemic as far as humans are
concerned, hence the nicotine patch.

You misunderstand the meaning of systemic. The nicotine patch is in
contact with the human skin. That is a contact usage.

It is systemic in plants like nicotiana that synthesise the stuff
internally in sufficient amounts to kill off would be sap sucking
parasites. Outside the plant it isn't all that stable and so would be
pretty useless.

You can get some plants to absorb practically any molecule small
enough
if you bathe their roots in sufficient amounts of it. Nicotine is far
too dangerous a compound to use in this way. Natural poisons are not
safe.

Regards,
--
Martin Brown

Thank you Martin, I think you say all I need to know right there. The
point about nicotine being systemic, the medical sites I read up about
nicotine mislead me by saying it is./

Annabel