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How to Get Rid of Poison Oak Plants

Identification, Killing Poison Oak Plants With Herbicides

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poison ivy versus poison oak

Photo of poison ivy vine with leaves at various stages of growth. Poison oak looks similar but the leaves are shaped like oak leaves.

David Beaulieu

How do you get rid of poison oak plants? Well, sound eradication methods begin with positive identification, so let's begin with that.

"Leaves of 3, let them be" is the familiar warning that applies both to poison ivy (Rhus radicans) and to poison oak. Poison oak often has leaves shaped like the leaves found on oak trees (thus the common name). The leaves of both poison oak and ivy turn red in fall, and both plants produce white berries. Like Rhus radicans, poison oak vines (or, sometimes, shrubs) are indigenous to North America. The former is more widespread but does not appear on the West Coast. Meanwhile, one type of poison oak (Rhus diversilobum) grows primarily on the West Coast and another in a few parts of the East.

Methods for Getting Rid of Poison Oak

Okay, now you have a better idea of what you're dealing with. But how do you get rid of poison oak? I'll discuss three options you can use to kill poison oak (wear gloves, long-sleeved shirt and long pants when undertaking this task, so as to protect as much of your skin surface as possible):

  1. Getting rid of poison oak manually.
  2. Applying herbicides to the cut stumps.
  3. Applying herbicides to the leaves.

Let me address each option separately.

The object in trying to get rid of poison oak manually is to pull it out by the roots. Make sure you dispose of those roots properly. And be especially certain that you do not burn them. Inhaling such fumes is extremely hazardous.

Another manual method for getting rid of poison oak (if it is growing on the ground, rather than in trees) is to choke it out by covering it with an impervious material. To accomplish eradication using this method, cut the plants down close to the ground. Immediately afterwards, place your covering material over the cut stumps. A variety of materials will do the job. An excellent choice is the poly tarp. You may need more than one, depending on the size of the tarps and the size of the area you need to cover. In your calculations, take into account that, if multiple tarps are required, you will need to overlap them by a foot or so. Tarps are readily available in stores, are not terribly expensive (if you shop intelligently), and are relatively durable.

Warning: poison oak remains...well, poisonous even long after it's dead. Protect your skin when you dig up the roots of the dead plants, and dispose of them properly. Manual eradication may have to be repeated. Note that manual methods may be practiced at any time of the year (except during winter in the North, when the ground is frozen), whereas methods involving herbicides are best employed during the height of the growing season.

Using Herbicides to Kill Poison Oak

Examples of herbicides that may be used for killing poison oak are glyphosate (e.g., the Roundup brand) and triclopyr (e.g., the Ortho brand).

Wielding your trusty pruners and a can of herbicide (or spray tank), you can apply the herbicide to the cut stumps of poison oak while the plant is actively growing. Cut the stem an inch or two above the ground and apply the herbicide right away. The fresh wound will drink in the herbicide, transporting it deep inside where it can do its damage.

Applying herbicides to the leaves of poison oak is most effective during the flowering stage (with triclopyr) or fruiting stage (with glyphosate). Such "foliar spraying" will have to be repeated until the poison oak is fully eradicated. Here are some more tips for using herbicides to eradicate the menace:

  1. Don't spray on a gusty day. Not only will you waste herbicide, but you risk having the spray blow onto your landscape plants and damaging them.

  2. Don't spray with rain in the forecast. Unless 24 hours or more of dry weather follows your spraying, again, you'll be wasting herbicide (as well as time and energy).

  3. Don't spray poison oak that is scaling a tree, as you could damage the tree. Manual removal may be preferable here, although you could dab (not spray) a bit of herbicide onto the individual leaves of the poison oak, so as to control the application carefully.

About's Guide to Walking offers a gallery of poison oak pictures.

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