What kills poison ivy?

Straight vinegar, lots of it. Vinegar is cheap.

round up. Lots of it. it may take repeated treatments. Once dead....remember it can still cause a rash. Do not burn any part of a poison ivy plant. The ursural...compound that makes the itch...and blisters can become air born. You don't want to breath it.

This may sound nuts but it does work. Goats thrive on poison ivy if you can manage one or two on your property.

The only thing i've found that kills it and it doesn't come back, is poring table salt on it. Pour all around the base of it and on the plant. I had to do this cause my husband is highly allergic to it and we had some that kept coming back, right at the gate going to the back yard. Table salt also killed all my ant hills. Just pour it around the hill and into the opening.

https://www.thespruce.com/tips-for-removing-poison-ivy-safely-2132618

I use a spray of Kills All.

That's why masks were invented.

We use Round up, the vine keeps coming back

3 cups white vinegar

1/2 cup table salt

1 tablespoon liquid detergent or soap (I use Dawn) for stick-to-itiveness.

Directions

1. Mix vinegar and salt until the salt is completely dissolved. Stir in liquid dish soap, and pour into a spray bottle.
2. Spray onto the green growing leaves of the plants.
3. Wait a week, then repeat on any survivors. Best time to apply: during a dry spell.

Repeat as necessary.