Leaves of Three, Let it Be!

By Paul James

I was hiking with my five-year-old grandson not too long ago, and we came upon a large batch of poison ivy. “Leaves of three, let it be,” I said, to which he replied, “Huh?” I’m pretty sure I had the same puzzled look on my face when my grandfather said the same thing to me 60 years ago. But you’re never too young to learn how to recognize poison ivy, and you’re never too old to learn how to get rid of it.

Oddly enough, poison ivy is related to cashews (I know, that sounds nuts) as well as pistachios, mangos, sumac, and the ornamental smoke tree. It’s a native plant as well, one that grows in every state except California (where they have the dreaded poison oak instead). And although we tend to despise it, poison ivy is important ecologically as a source of food for wildlife. Birds love the fruit it produces, as do deer and mice. And many insects eat the foliage.

About 10 to 15 percent of the human population is immune to poison ivy, or more specifically urushiol, the chemical responsible for giving the rest of us a nasty rash. I know a guy who can sleep in a bed of poison ivy and wake up unfazed. But I’m not that lucky, and chances are neither are you. So when I see poison ivy, all I want to do is get rid of it.

One way to do that is to dig it up, roots and all, but not before donning long pants, a long-sleeved shirt, and gloves, all of which must be washed or tossed immediately after. It’s also a good idea to apply a product called Tecnu (available at drug stores and online) to exposed skin both before and after exposure. And fair warning – if you leave behind one tiny piece of rhizome in the ground, you’ll soon have more poison ivy, which is why you’ll want to dig at least eight-inches deep to get all the roots. When you’re done, bag up the vines and trash them, and wash your tools too.

You can also smother the plants by covering them with cardboard, carpet remnants, or black plastic. It’ll likely take several months to kill the plants outright, but it does tend to minimize your risk of exposure.

Of course, the easiest approach is to rely on an herbicide, preferably one that’s labeled for vines or poison ivy specifically. Most of them contain either glyphosate or triclopyr, both of which are synthetic chemicals. However, there’s an organic alternative called Pulverize Weed, Brush, and Vine Killer that works great as well, although two applications may be necessary to eradicate the vines.

A few things to keep in mind when working around poison ivy: every part of the plant is poisonous; the urushiol is present in the stems even when the plant is dormant; and you can still get a rash long after the plant is dead. Whatever you do, don’t burn the plants because the urushiol can get into your eyes and lungs.

Finally, realize that poison ivy leaves can be dull or shiny, the leaf margins may be smooth or serrated, and the little stems (petioles) that connect the leaves to the main vine may not always be red. In other words, there’s no one poison ivy. In fact, not all species have three leaves. There’s one in Texas that has five leaves, which is no surprise of course, since everything’s bigger in Texas.