The organiphobes recommend spraying 2,4-D and other toxic herbicides but that's a very bad idea. Toxic products contaminate the soil, the water, the air, wildlife, pets, you and me. Plus, they don't work very well anyway. Besides being very dangerous toxic chemical for the soil, water, air and you, it will kill your trees. Poison ivy must be physically removed.
Goats will eat it into oblivion for you or you can hire someone to dig it out. Then as it starts to grow back, the young returning growth can be sprayed with the vinegar-based herbicide. Add one ounce of d-limonene such as Orange TKO and one teaspoon liquid soap to one gallon of 10% vinegar made from grain alcohol. The skin rash can be treated with the juice of comfrey. When applied early on, it is quite effective. Poison oak has a more oak-like leaf but has the same properties as poison ivy.
Poison Ivy with Fall color.
Poison Ivy "Leaves of three...let them be!"
Reader photo submitted by Dan M. Roberts
Poison Ivy vine not in bloom. You can still get the poison rash from
this non-blooming vine if you touch it when trying to remove it.