Riverwoods Preservation Council

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Poison Ivy
 Poison Ivy

 May - June, 2007



(photograph courtesy of Sue Auerbach)

Poison ivy, which thrives in Riverwoods, may be seen as an individual plant or shrub growing close to the ground, or as a vine climbing high into trees and onto walls and fences. It often has reddish stems. When vine-like, stems can be up to an inch in diameter, though when that large, they appear as woody, hairy, brown vines.

Identifying the plant
Poison ivy has three leaves. Two leaves are immediately opposite one another while the third, center leaf, is on a slightly longer stalk. In the Riverwoods area, the most distinguishing characteristic is that the two leaves opposite one another usually are each shaped roughly like a mitten, with a large lobe and an adjacent smaller lobe. The size of the leaf, its glossiness, and the color of the leaf underside and stem, are not reliable identifying features.

Contact with plant
As anyone who has had a major encounter with this plant can attest, it is a most unwelcome inhabitant of our area, producing an annoying and at times painful (occasionally dangerous) blistering rash. The oily toxin urushiol causes this reaction and the severity (which sometimes requires medical attention) varies with individuals, and from year to year in the same individual. In most cases, sensitivity is developed only after one or more prior exposures to the toxin.
Because reaction to the toxin occurs when the toxin penetrates the skin, quick action --generally within about 5 minutes of exposure -- will often avert a problem. Otherwise, redness and swelling typically appear within 12 to 48 hours after contact, followed by blisters.

What to do if you touch it
If exposed to poison ivy, follow these steps:

  1. To avoid contaminating your home, remove contaminated clothing and, if possible, wash or rinse affected areas before entering the house.
  2. Cleanse your skin immediately with generous amounts of rubbing alcohol (isopropanol). If rubbing alcohol is not available, use soapy (or even plain) water. Be careful to clean only the contact area, to avoid spreading the toxin to other parts of your body.
  3. Take a shower. Don’t reuse a soap bar used for the initial cleaning, as it may be contaminated.
  4. Wearing disposable gloves and using rubbing alcohol, wipe off shoes, clothing, tools and anything else that contacted the toxin. Immediately and carefully discard the gloves after decontamination is complete.

Contrary to popular myth, no toxin is contained in the rash and blisters, so they are not contagious and will not spread. The rash and blisters appear only on the body parts that came in contact with the oily toxin, and typically disappear within two to three weeks. Mild cases may be relieved with wet compresses or soaking in cool water. Itching can be reduced by oral antihistamines, baking soda, calamine lotion, zinc oxide, kaolin, and over-the-counter corticosteroid medications.

If large areas of the body have been contacted, or if the affected area has any scratches or wounds, seek the prompt advice of a physician, as treatment must be-gin within a few hours after exposure to be most effective. In severe cases, a prescription corticosteroid may be appropriate. Because topical corticosteroid is not considered effective once blistering has begun, an oral version of the medication may be indicated.

Beware - the whole plant is poisonous
Remember that all parts of the poison ivy plant, including leaves, stems and roots, are poisonous at all times of the year. Any oil remaining on clothing and foot-wear can remain toxic for a year or longer. And while dogs, cats and other pets are not sensitive to poison ivy, they can transmit the oily toxin on their hair. Other potential carriers are garden tools and anything else that comes into contact with the plant. Even smoke can contain the toxin, and inhalation of toxin-bearing smoke can cause a medical emergency. For this reason, poison ivy plants should never be burned.

Poison ivy is hard to control. It spreads by roots which are difficult to remove. Birds eat the berries, spreading the seeds.

The best time to attempt to control poison ivy is from May through July, when the plants are flowering and most dangerous. Manual eradication is possible, so long as all parts of the plant — leaves, vines and roots — are removed. Alternatively, foliage can be sprayed with a general herbicide, such as glyphosate (often sold under the brand name Roundup). Again, be careful to avoid desirable plants, as this non-selective herbicide kills any vegetation it contacts. Cut large vines a few inches above the ground, and immediately apply glyphosate to both freshly cut ends, so that the chemical travels to all parts of the plant, including the roots. Since the dead vine and leaves will continue to contain the toxin, they should be left in place or removed and disposed of carefully. Poison ivy is quite persistent, so multiple applications of glyphosate may be required. Manual eradication is also possible, so long as all parts of the plant – leaves, vines and roots – are removed.

© Riverwoods Preservation Council- - Page last updated: December 2009