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Webmaster's Note: I've added this page to the 1st-Aid & Health section of the website since Poison Ivy is very common throughout Oklahoma

As an active fisherman and hiker since I was a kid, I've always known what Poison Ivy looks likes in almost any form. I am, however, I'm constantly amazed at how most people I've ever met know very well to "avoid" Poison Ivy but don't have the slightest idea how to recognize it!

While I've never had a reaction to Poison Ivy despite unintentional contacts over the years, I avoid it whenever possible since apparent "immunity" can be lost through repeated contact. Since several friends over the years have had severe reactions (lasting weeks and even months) from an apparent first-contact, I try point it out to others whenever I see it in yards, parks, or in the woods.

Poison Ivy even grows here and there throughout the OU campus, (without permission of the OU Landscape Department) usually adjacent to individual trees, or in peripheral areas such as Brandt Park and other wooded locations.

The following information is from my own experience and from articles I've read over the years.

-Richard Hamilton, OUPD Webmaster

Everything You Wanted to Know About Poison Ivy but Were Afraid To Ask


Poison ivy [Toxicodendron radicans] is found throughout most of the United States and southern Canada. It is also known under a variety of other names such as:

three-leafed ivy
poison creeper
climbing sumac
poison oak

While there are three varieties of Poison Ivy common to Oklahoma, all have the same general appearance and poison characteristics.

Poison Ivy can grow as a self-supporting woody shrub, as a thin trailing vine running along the ground, or as an aerial-rooted vine growing on shrubs, trees, power poles, and fences. The aerial-rooted specimens often have a wooly or fuzzy rope-like appearance. Older (ten years or older) vines can grow to several inches in diameter as high as 30-feet. Poison Ivy is a perennial plant that is reproduced by seeds and woody rhizomes. (Click HERE for photos of shrub and vine forms.)

Poison Ivy's distinctive leaf pattern is groups of three leaflets occurring alternately along the stem. Leaflets are usually fairly smooth, but may be either a dull or glossy green. Leaf edges may be smooth, toothed, and (rarely) lobed. Large mature leaves often have several large teeth (cutouts) on either side of the broadest part of the leaf. Leaflet sizes vary from a quarter-inch to over 2 inches in length. Leaves on the same vine often have a number of color and shape combinations. Note: The thirteen-inch "monster" 3-leaflet cluster shown above is from a nine-foot tall Poison Ivy "shrub" in my yard - which is actually a dwarf "remnant" growing out of the root-system of a 30-foot tall "vine" form plant that I cut down several years ago.

When leaflets first appear in the spring they are usually notable by a shiny, reddish-green color, usually slightly toothed and not as smooth as more mature leaves. During the summer the leaves are various shades of green, usually dark. In the fall leaves turn various shades of red, orange, and yellow before turning brown. Flowers, though usually brief and rarely noticed, are clustered and small, and are yellowish in color. The berry-like fruit ranges in color from yellowish-green to whitish-gray and is clustered, small, round and waxy, extending out above a leaflet group.

A number of similar "sayings" describe a good warning for Poison Ivy:

leaflets three, let it be
leaflets three, let be
leaves be three, leave be
if leaves be three,
leave it be

Pick one and remember it!



Millions of people have reactions to Poison Ivy each year. The allergic agent in Poison Ivy is an oily substance called Urushiol, which is a collection of oleoresins. It is found in all parts of the plant and can be transported by wind or smoke as well as through direct contact. Symptoms of poisoning range from mild itchiness and redness to severe oozing lesions with fever. While humans may not develop dermatitis from the first contact, most people are sensitized the first time.

Note: The Urushiol can contaminate footwear, clothes, tools, and pet fur, thus there is always a potential of transferring the plant oil without any direct skin contact at the time of exposure. Here's a scary thought: The oil can remain active on footwear, clothes, and tools, etc. for as long as a year. Smoke inhalation (breathing the smoke) from burning Poison Ivy, can also cause severe poisoning, as the soot particles can carry the oil.

Poison ivy dermatitis (irritation, blisters, sores) can start from within a few hours to up to a week after contact (or even longer with subsequent repeated contacts with contaminated clothes and tools.) It may progress from itchiness and swelling to inflammation, and the formation of lesions and blisters. The time factor is dependent upon personal sensitivity, the amount of exposure, and the season. Spring and summer are the seasons of greatest potential for poisoning. Damaged leaves and stems most readily produce the oil for significant contact, which is easily transferred to skin as well as clothes and tools.

Scratching will spread the reaction as long as the oil has not been washed from the skin. The fluid from blisters caused by the oil will not spread the reaction (once the skin has been thoroughly washed.) Washing with Dawn/Joy/Palmolive dishwashing liquid (any modern dishwashing detergent with a "degreaser" agent - not just normal soap!) or lye soap (though I don't know that many people who keep lye soap around the house nowadays) is reported to neutralize the oil of Poison Ivy for many people.

A good source for information on various treatments is:
Poison Ivy, Oak, & Sumac Information Center

My best advice for treatment would be to consult a physician, or at least contact your pharmacist for possible over-the-counter remedies.

Click HERE for a Poison Ivy photo gallery...


Digging it up:

While Poison Ivy can usually be dug up when the soil is wet and there are only a few plants. However, any attempt to remove roots from dry soil is usually unsuccessful since some rhizomes most likely be left behind to sprout.

Cutting it:

Repeated cutting to the ground will eventually starve-out the plant root system. Cutting with a powered "weed-eater" is obviously not a great idea, since it increases the likelihood of spraying the plant oil all over the tool and the user!

Digging or cutting is not recommended for persons with a known sensitivity to Poison Ivy.

Nuking It:

A number of herbicides are very effective in the control of poison ivy. Check with your local home and garden center or area agricultural extension office for more information regarding products available for home-use or other use. The primary residential herbicides used to control Poison Ivy (at the time I wrote this article) include Glyphosate, Amitrole, 2,4.D, and Triclopyr.

Roundup or Kleenup (both are glyphosate) may be applied to the leaves of Poison Ivy. It is absorbed through the leaves and carried throughout the entire plant. Glyphosate has no soil activity. After spraying, do not try to remove the plants for several days in order to allow the chemical to be absorbed throughout the plant. Remember that dead Poison Ivy still contains its poisonous oils. Avoid over-spraying as glyphosate will kill adjacent plants, including grasses. Glyphosate may be listed on a label as "isopropylamine salt of glyphosate".

Amitrol-T or Weedazol (Amitrole) may be applied, and works in the same manner, as glyphosate (above), but remains active in the soil for several weeks after application. This soil activity prevents the planting of new vegetation in the treated location for several weeks. Do not use in soil where food crops will be grown or in grazing-animal areas. Amitrole may be listed on a label as 3-Amino-1,2,4-triazole.

Weed-B-Gon, Jet Weeder and other products containing 2,4-D are not the most effective solutions for controlling Poison Ivy, but 2,4-D does not kill grass. It may be mixed with 2-4-DP when used on larger "woody" Poison Ivy plants for increased effectiveness. Repeated treatments will probably be required as it usually will not kill the root system through a single application. Apply at least 6-12 hours before watering or anticipated rainfall. This active ingredient be listed on a label as Diethanolamine salt of 2,4-Dichlorophenoxyacetic acid (for 2,4-D) and Diethanolamine salt of 2,4-Dichlorophenoxypropionic acid (for 2,4-DP). Note: Some plants are VERY sensitive to extremely small amounts of 2,4-D and 2,4-DP. If you must use the sprayer for other uses, rinse it carefully several times with an ammonia solution (including nozzle, hose, reservoir, etc.) to remove all trace amounts of the chemical.

Garlon, Redeem, and Brush-B-Gon (Triclopyr) works in a similar manner to 2,4-D, but has a longer soil activity. Do not plant trees in treated soil for a period of at least six months. It also does not affect grasses.

Crossbow (a mixture of 2,4-D and triclopyr). is one of several herbicide "mixtures" that may control Poison Ivy. Read the labels carefully for the effects of such mixtures, as well as for all herbicides applied around the home.

Not all of the listed products may be available in your area or may not be allowed for home-owner use without special licensing.

Products for non-residential control of Poison Ivy, such as along fence lines as well as clear and timber areas, include Banvel, Velpar, 2,4-D ester+2,4-Dp ester, Tordon, and Oust.

This article is not intended to endorse the use of any of the commercial chemical products listed, nor an affirmation of their reported effectiveness. They are listed only as a possible remedy which may be available in your area. I'm not a chemist, herbalist or any other sort of expert on this subject, nor do I play one on TV. I've personally had very good luck with Roundup, but maybe the plant was about to die at any moment anyway. Who knows?

I'm not much for chemical solutions (pesticides or herbicides) but dealing with Poison Ivy can be a nasty business. Just don't end up poisoning yourself, your family, your pets, or your favorite tree through poor use of the listed herbicides! The listed herbicides are probably more dangerous than the Poison Ivy if used improperly!

Likewise, the general description of the Poison Ivy plant and its various characteristics are simply my best knowledge through personal experience and reading. If you are interested in learning more about Poison Ivy there are numerous sources of information on and off the Internet. For medical information, consult a physician.

This article represents my opinions only, and not that of OUPD, OU, or the State of Oklahoma. It's free advice and worth every penny of the price.

        -Richard Hamilton, OUPD Webmaster.

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