Poison ivy: Easy to identify, tough to control

Poison ivy can be confused with other plant species. It can spread to you from a pet's fur, touching someone who came into contact with it, from garden tools or even from smoke from a burning vine. It's also tough to kill.



May 25, 2021 - 9:08 AM

Leaves of three — let it be! I’m certain that someone has told you this before in an attempt to keep you away from poison ivy. It is true that poison ivy has three leaflets.  However, the untrained eye can easily confuse poison ivy with other plant species such as Virginia creeper. 

Poison ivy occurs in three forms: an erect woody shrub, a ground cover that creeps along the ground, and a woody vine that will climb trees. It can grow to 10 feet or more as it climbs up trees or fences. All parts of poison ivy — leaves, sap, roots, and burning vines, are poisonous at all times of the year. All of these plant parts contain a toxic oil which causes irritation to the skin on many people. The typical reaction is an itchy rash with clear blisters about 2-3 days after contact with the oil. 

As stated earlier, poison ivy always has three leaflets. But the leaf margins can vary.  They can be toothed, incised, lobed or smooth. The size of the leaf can also vary. The middle leaflet is larger than the other two and the middle one is the only leaflet with a long stalk. The other two are closely attached to the leaf stem. Virginia creeper has the same habitat as poison ivy and is often confused as being such. However, if you look close, Virginia creeper has five leaflets rather than three.   

Have you ever gotten poison ivy, but swear that you didn’t touch it? Yes, it can happen. Poison ivy can be spread to you from your pet’s fur after they have ventured out to an infested area; from touching the clothing of a person who has come in contact with it; from garden tools that may have been used to pull down or chop vines; and even by the smoke from a burning vine. Burning poison ivy will cause the toxic oil to vaporize and be carried in the smoke. Believe it or not, the oil from poison ivy can remain active on clothing and footwear for as long as a year. 

Poison ivy is not the easiest plant to kill. It is a tough plant and difficult to eradicate without killing desirable plants in the process. There are three methods used to destroy poison ivy — pulling the plants out by hand, cutting the plant off at the vine and treating the stump, or spraying the plant directly. The first two methods are more risky as far as infecting yourself with poison ivy. 

The method used depends somewhat on the growth form the plant has taken. If it is in the ground cover form, direct spray or hand pulling is often used. If the plant is in the shrub form, direct spray is routinely used. For plants that are a woody vine and climbing, the preferred method is to cut the plant off at the base and treat the sprouts after they emerge. With any method, make certain to wear gloves and preferable a long sleeve shirt. Wash clothing and your skin immediately after you have finished. 

Several herbicide products are labeled as “Poison Ivy Killers.” The products are premixed, ready-to-use products containing the active ingredient triclopyr. Glyphosate, 2, 4-D and dicamba (Banvel) offer fair to good control. Once a treatment is made, wait 3 to 4 weeks for the product to work before applying any additional herbicide. Read label directions and follow with care as these chemicals cannot differentiate between poison ivy and other plants – meaning you might accidentally kill desirable plant species while trying to kill poison ivy.

Krista Harding is a K-State Research and Extension Agricultural agent assigned to Southwind District.  She may be reached at [email protected] or 620-244-3826.