Dwight said:

I heard about that one time so I took some grocery store vinegar (about
5% acidity) and put it into a sprayer and sprayed some grass etc. in my
gravel driveway. In a couple of days the weeds were dead. In a couple of
weeks the weeds were back.

I did not try it on poison ivy.

My neighborhood garden expert recently recommended vinegar for poison ivy.
But she said that you need to get 7% acid. Not sure where you get it.

Dave
http://members.tripod.com/~VideoDave