On Fri, 9 Apr 2010 14:55:07 -0700 (PDT), mike wrote:

http://www.hort.uconn.edu/ipm/homegr.../60poisivy.htm

Hi Mike,
That's a very interesting article, which says urushiol "is very stable, and
dead and dried material is as hazardous to sensitive people as an
actively-growing plant. It is equally active in the dead of winter. Many
people have caught poison ivy from dead poison ivy plants. It usually takes
a year or so before the toxic properties weather away".


Even though the urushiol in poison oak is different than that in poison ivy
(http://pubs.acs.org/doi/abs/10.1021/jo00215a002), your point is valid,
that the urushiol might "weather away" (whatever that means). I suppose it
oxidizes to something other than urushiol.

Interesting ...

I'm digging in google to try to find what that weathering mechanism might
be as it's mighty interesting because that might actually be a way to
combat it. Maybe we can hasten that 'weathering' to a few days instead of
to a few months or years?????

http://www.japanese-antiquities.com/...ed-birth-bowl/
"Urushiol is an oily substance contained in the sap and when it is exposed
to humidity and warmth, an enzyme is activated that extracts oxygen from
water and supplies it to the urushiol. Then the urushiol solidifies, which
forms a hard film."

The Japanese have mastered a way to make Urushiol non inflammatory:
http://www.pentrace.net/east/wajima/urushi.html

Even so, the thicket is so thick that a human can't walk through it and it
goes over twenty feet high (see the pictures previously posted):
http://img338.yfrog.com/gal.php?g=po...hiolchapar.jpg

So, I'm not sure how I would even think of applying a herbicide to kill
huge amounts plants I can't even get to without hacking my way through
them.

But I do thank you for the idea. So far we've gotten a few good ideas. And,
if we can find a way to inactivate the urushiol from the toxicodendron in
less than a few months' time (i.e., hasten the weathering), we'd all be
doing the world a favor!