I've got a patch of land with trees and understory bushes and weeds mixed with poison ivy. Altogether it is about a half acre. I'd like to keep the trees and bushes, but get rid of enough poison ivy to make it safely accessible.

What would be the best approach?

Following this

Me too.

Moosetrot

Although a temp solution, I had the same thing and fenced a patch of woods off with electric fence. Lady down the road turned 3 horses loose in there and the first thing they did was selectively went after the poison ivy. I can remember one old mare ripping the vines off the trees. They are not affected by it and apparently it has an analgesic affect on sore bones and joints. Week or so later, there wasn't any ivy left to be found.

I had some in my woods. I killed it with Round Up. Any woody brush killer such as Crossbow will kill it. The stuff I had never came back.

As was said, spot spraying the leaves with roundup is your best bet. I don’t like the stuff, but for certain things like this it works wonders. Happy trapping! ScottW

Goats hammer it, I've been grazing my goats on it to remove it.

Goats, cows, horses and deer will all eat it. Trouble is the plant will just grow back, even after many summers of being grazed off it still survives. Gotta spray it to kill the roots.

Plants eaten by animals typically come back.
Roundup is your solution.

If the name "Roundup" makes you spooky, just buy another weed killer that is glyphosate....

Poison Ivy is a weird plant. I know some folks that can rub it on their body and not get the rash.
I also know some that can look at too long while driving down the highway with their windows down and be at the doctor the next day because their entire body is covered in a rash!

Buy some Par three. That’ll take care of it!

Crossbow will kill it. It will usually only burn a tree or clover and they will survive if you accidently hit them also.

I have found RoudUp to work well as does old gasoline right on the foliage.
Poison Ivey Rash is your body's Histamine reaction to the Urushiol toxin.
It runs in about a 7 yr cycle, ie: If you get a bad dose, your body will react to it for 7yrs on a diminishing scale, till your full resistance gets back to where you were.
To give yourself about a 6 hr relief window so you can sleep, scrub the rash with a rag and water as hot as you can stand it. This will over stimulate your body's use of Histimine till it's gone, then it will slowly rebuild. Repeat as necessary.
Calamine Lotion will help, and an OTC Anti-Histimine will help.

First and foremost: LEARN WHAT P.I. LOOKS LIKE AND AVOID IT! Pets can bring it in to you on their fur, and rub it on you or your pillow etc. Just the pollen on the wind can cause a reaction in some folk.

I've never seen poison ivy grow on trees, however poison oak will I believe.

Crossbow works the best to eliminate poison ivy, 2-4D and Gly works for a while but it will come back.

cut the vine, paint the stub end with straight croossbow, if its a big vine,, drill a hole straight down in it and fill the hole with straight crossbow.

Yep....drill a hole in that vine...Lol...you'll be in an itching frenzy for 3 weeks as you'll get that toxin all over you...but hey...if you do this and pour on the herbicide...you'll kill that vine.

BigBob knows his poison ivy stuff! Good info.

Got it bad years ago digging sassafras roots for my Granma. No leaves on the ivy in the winter but the roots are just as poisonous that time of year.