On Tue, 08 Jan 2013 12:42:29 -0600, homeowner wrote:

I dont know how long it takes for that oil that causes
the skin irritation to go away after the plant is dead.
You'd have to do research on that.

I did do the research!

This scientific site says it lasts 100 years!
http://online.sfsu.edu/bholzman/cour...nalwebsite.htm

Here's the verbatim quote from that San Francisco State web site:
"What is amazing is specimens 100 years old have been known
to cause dermatitis in humans, because urushiol is a relatively
stable compound, and can remain potent for years in the absence
of oxidation (Armstrong & Epstein 1995)."

I would think that, outdoors, exposed to the elements, the urushiol
would only be allergenic to humans for something on the order of
perhaps only 5 or 10 years, but, the point is that the oil from
Toxicodendron diversilobum will last far longer than we'd like it to.

The verbatim statement from that web site below leads me to
conjure the thought that this single plant on my property can
infect every single person on earth, since it was literally
dripping drops of sap within a few minutes of cutting the plant!
"Urushiol is so incredibly toxic that it would take only one
ounce of it to affect everyone on the earth with a rash
(Brooks 2001)."