Poison ivy is a common and widespread plant that can cause a severe skin irritation when its oils come into contact with human skin. The severity of the irritation varies, but it almost always causes a red, itchy rash. Contact with the plants should be avoided, and killing them when they are in your yard or garden is recommended to minimize the possibility of contact.
Identify the plants. Look for clusters of three leaves covered in a glossy sheen. The center leaf of this cluster will often be sticking out on a leaf stalk, while the other two leaves will be joined directly to the stem. Look for white berries, as poison ivy plants also produce small fruits of about 1/4 inch in diameter that are lined and look similar to peeled oranges.
Buy an herbicide. A common herbicide is glyphosate, which is sold under the names Round-up and Kleenup. Purchase a bottle of this at a hardware store or a gardening specialty store. Glyphosate is applied to the leaves of the ivy plant and then carried throughout it, even into the roots, making it an effective killer for poison ivy, which can regrow shoots from just roots.
Apply the herbicide. Spray the poison ivy plants with herbicide, making sure not to spray other wanted plants in the area as the herbicide will kill them as well. Spray the plants until they are wet with the herbicide, but not dripping. Spray on a day when it will not rain for six hours after application, as the plant needs time to absorb the herbicide and rain can reduce its effectiveness.
Inspect your poison ivy. Make sure the plants are starting to wilt and turn brown after a couple of days. If they are not, they may not have absorbed enough of the herbicide and you must reapply it. Be sure not to touch the poison ivy even if it appears to be dead as the irritating oils can remain long after the plant dies.