Tom The Great wrote:

Years. You hear about families where the dog got some on his fur, then
at home he smeared it on the walls at dog height, then years later they
have a kid, and when the kid starts crawling he contacts the poison ivy
on the walls, and they spend weeks trying to figure out where he is
getting a rash from.


Years???!!!!!

That is a long time.


How about centuries! The Japanese used to make a lacquer from a plant
that is a 1st cousin to poison ivy. They would use the lacquer to
finish decorative wooden bowls. Centuries old bowls handled today can
still cause a poison ivy outbreak.

Speaking of 1st cousins to poison ivy, cashew nut plants fall into that
category.

Bob