Smothering would work just fine, just keep an eye out for runners leaving the smothered area...

Poison Ivy in my yard vines up a tree and up the fence, so I can't smother it. :-(

Now I'm wondering, tho, if the poison ivy oil will remain after the plants are dead. How do you get rid of that w/o physically removing the plants?

I am having the same problem with poison ivy...and I can't get rid of the source as grand-daddy PI is in my neighbor's yard. This year, at someone's suggestion, I poured gallons of white vinegar on it. So far it is dying...if it stays dead, then I will carefully remove the plants. I have heard the you can't plant anything in the area for at least year after the vinegar dousing...but I am new at this myself. I'll keep you posted.

Simply smothering Poison Ivy will not get rid of it. The roots will simply send out runners to find some other place to grow up. The only really effective way to eliminate this "weed" is to dig it out, using lots of care so you do not get the plant oil on your skin. Old clothes, heavy gloves, stuff that can be discarded aferwards because you do not want to wash them in your clothes washer even alone.