I grew up never really being able to identify poison ivy; "leaves of three" will take you only so far, given the number of trifoliate plants out there. I just didn't have to know what it looked like, and the only part of the plant I could reliably identify was its tree-bound vine, resplendent in tiny red "hairs" of aerial rootlets. (Before anyone comments: yes, I'm aware you can develop an allergy to poison ivy at any point in your life, and I don't take my immunity for granted--though I did as a kid!) It wasn't until I met my wife Beth that I studied the finer points of poison ivy ID; she's incredibly allergic, and on one occasion, her dachshunds brought some urushiol oil (the toxic substance in poison ivy) in from her yard, leaving her arms terribly broken out right before a friend's wedding (see the picture at the end of this post; there's a reason she's wearing black and opera-length gloves to a wedding!)
Last summer, when we first looked at Chateau Papillon during our house search, I did walk the yard, but I didn't notice the poison ivy at the time. Granted, we'd been several weeks into a minor drought, so it's possible there wasn't that much foliage present. Fast forward to our move to home ownership, and in making detailed plans for the yard in late winter, I discovered several trees hosting poison ivy vines.
I spent a warm late-February weekend sawing through the vines--some 2" or thicker in diameter--at several points from the ground up, hoping to nip the problem in the bud (figuratively and literally) before spring came. For the most part, I was successful; many of the vines never leafed out at all, and those that did largely put out new growth very close to the ground.
After that, it was a game of wait and watch, particularly in the back "wild" corner of our yard. I pulled up several plants as they appeared, making sure to get the entire vines and root systems for each, and also put down "sheet mulching" along a large periphery of the yard (whereby overlapped cardboard sheets beneath several inches of mulch--obtained free from Fairfax County--helps kill off any weeds beneath). Our ridiculously rainy spring (almost 5" above normal already) has complicated the task, keeping me out of the yard for a week at a time and giving plenty of impetus for new weed growth, but I've successfully pulled up three garbage bags full of poison ivy to date.
Now, for the shocker: in watching our bluebird house, I noticed that one of the "branches" of a nearby tree was in fact poison ivy. I'd missed it in the late winter vine cut, thinking it to be a tree limb; the vine was at the back of the tree, and who'd expect a six foot long "branch" to be the spawn of a weedy vine? But spring brought those terrible little flowers and the beginnings of berries--a treat for birds but a pest to us, along with ivy leaves a good 5-6" long and 3" wide. Eeek!
Pictured above is one of the lower-hanging poison ivy "branches," near our bluebird house. I've since trimmed it back significantly, but the branches go up the tree (sprouting from a 2.5" thick vine) 30 feet or more into the air, so I'm not entirely sure how I'm going to control it in the long term. I sure don't want the berries to go the route of bird poop and spread the weed across parts of the yard I've managed to keep clear of poison ivy.
Worst, we have plants and trees growing in close proximity to the poison ivy, meaning I can't just spray weed killer. Nope, it's double-gloved hand-pulling of the vines and foliage, and crossed fingers that I don't accidentally give myself a massive exposure and trigger an allergic response.
I certainly don't want to end up like Beth did, taking steroids for a couple of weeks with massive welts from the weed along my arms or legs. And given how much our dogs enjoy the yard, I don't want them bringing poison ivy inside on their fur to cause an allergy attack on Beth, either.