Question: We have found poison ivy growing on trees in our side yard and are afraid it will spread. Will pulling it out take care of it … or what do we need to do to get rid of it?

Answer: First of all make sure what you have is poison ivy.  Eastern poison ivy (Toxicodendron radicans) is a woody perennial vine with compound leaves that occur in sets of three (trifoliate).  The edges of the leaves may be smooth, wavy, lobed or toothed and could even resemble oak leaves. Atlantic poison oak (Toxicodendron pubescens) looks much the same as poison ivy but it grows more upright and its leaves have hairs on both the upper and lower surfaces. Poison ivy is fast growing and self-propagating by underground rhizomes and seeds. The seed may also be spread by birds and animals that eat the small fruit. As the vines grow they will attach to trees and structures with their hairy, aerial roots along the stems.  

All parts of the poison ivy plant are poisonous because of the irritating oil, urushiol, which is a colorless or light yellowish oil found in the leaves, stems, and roots. The plant’s oil content is at its highest in spring so this is when we should be extra careful when around poison ivy. Because the urushiol oil can remain active for months, even on dead plants and roots, it will remain active on tools, clothing, and the fur of pets so we must also take protective precautions when working to control poison ivy. Therefore everything that comes into contact with any part of the plant’s oil should be cleaned carefully. If you are extremely sensitive the oil should be washed from the skin within ten minutes of exposure using running water and soap that does not contain oil, as these type soaps may actually spread the poison ivy oil and make it worse. If you are less sensitive to the irritation of the urushiol oil you may have up to four hours to wash it off. After this length of time it is very difficult to remove with soap and water.

Control

Poison ivy can get started in the home landscape from a seed dropped by a bird and can quickly become a problem. Poison ivy can be difficult to control when it grows in shrubs, ground covers and lawns. For minor infestations small plants may be dug up or repetitively cut back to the ground. Start cutting them back in early spring, about the time you first start to notice the leaves emerging. Inspect the area about every two weeks and if you see new plants emerging or any green growth cut the shoots back to ground level again, eventually they will starve to death. If this is the route you plan to take be sure to protect yourself from coming in contact with the oil.  Wear long sleeves, long pants, and protective gloves. Always launder these protective clothes separately from your regular laundry.  

If you plan to eradicate poison ivy chemically, care must be taken not to allow any of the herbicide to touch the foliage, stems, or trunks of desirable plants. If the bark of ornamentals and other desirable plants is thin, the herbicide may move through the bark into the plant’s food and water transport system (phloem and xylem elements), and result in death or severe injury. Some herbicides can have residual effects on the soil when applied, which could affect other plantings now or in the near future, so always be sure to follow label directions and if you are not sure do not proceed until you are. Although care must be taken to protect desirable plant foliage when applying to poison ivy, glyphosate is probably the safest herbicide to use in the home landscape as it is less apt to move through the soil and be absorbed by roots and injure existing woody ornamentals. Glyphosate works best when applied at the correct time, between 2 weeks before and 2 weeks after full bloom (early summer). As always with any chemical application, take safety precautions and follow label directions. The label is the law!

We get many calls each year about people mistaking Virginia Creeper and other vines for poison ivy or poison oak, so we like to remind people of the simple rhyme “Leaves of Three, Let it Be, Leaves of Five, Let it Thrive.” It’s a fun way to remember the differences and to teach children when not to touch.

If you have any other questions about poison ivy or the eradication of it please call Wendy Ulrich at the St. Clair County Extension office at (205) 338-9416 or email ulricwg@aces.edu.