Yes.

Thank you both!

Alas, letting it be isn't an option since it will get into the rain gutter. Unfortunately, it's growing from my pile of fallen branches and other yard debris, so it's going to be hard to get to its root. Dang! I was hoping it was some berry vine.

''Let them be" refers to not touching the plant. Not to letting it grow where it likes.

Bottom left you also have some English Ivy. That's also what the dead stuff on the wall is.

There are many plants that have 'leaves of three', so not all tri-leafed plants are a problem, but yes, this is poison ivy. Learn to ID it. I would use a weed-killer at this point. You may have to re-treat.

Thanks, all!

Poison ivy and cockroaches will eventually inherit the earth. I am very reactive to poison ivy. It is growing more potent in response to higher C02 . levels.

It's a little hard to tell from your picture, because there are many plants that look like poison ivy. Three leaves does NOT definitively mean poison ivy! One good way to tell is the petiole (the stem that joins the leaf to the stalk) on the center of the three leaves is longer, in poison ivy, than the petioles that join the two side leaves to the stalk. I *think* I see that in your picture, but it isn't clear. Take a close look. Boston ivy has three VERY similar leaves, but the petioles are all the same length.

Also, poison ivy is a vine that climbs mostly by spiraling around. Other climbers climb with tiny suction cups. Poison ivy does not have those tiny suction cups. Look carefully at how your plant is climbing the wall. If there are sticky pads, it isn't poison ivy.

It's very clearly PI which climbs surfaces by hairy looking aerial roots. They are visible in the picture. The three separate leaflets on their petioles are also clear. Boston Ivy has an entire lobed leaf, so no petioles at all.

what floral_uk said

I think that's right that the center petiole appears longer. Needed to blow up the picture provided by the OP. Aerial roots are not a discriminator of poison ivy.

"Aerial roots are not a discriminator of poison ivy." No, they're not. But PI has a quite distinctive type. And they're very clear in the photo. There really isn't anything else the OPs plant could be. I can't think of any N American creeper with similar aerial roots or leaves. I recently came across another mnemonic to add to "leaves of three ..", "hairy rope, don't be a dope."

On phone or iPad tapping the picture gives a large clear image. On a PC you need to enlarge and the image is less sharp.

Toxicodendron radicans (Poison Ivy) does NOT climb by twining! That is not correct at all; it has the aerial roots for attachment, or it wouldn't be on that brick wall. Nor would it be on any of the very large trees here at the Valley with which it has become quite a happy resident.

Poison Ivy is also one of the few eastern North American native vines that forms woody branches extending from surfaces that they've climbed. I think that would separate it from most other species with which it might be confused. It forms cloudy white/creamy fruit after flowering.

FINALLY: learn to ID vines from their dormant buds. Then, you can avoid contact and rash when you come across these plants when out of leaf. Poison Ivy buds look nothing like any of the other species mentioned.