Classics
The following article has been selected because it is deemed very important to the arboricultural profession
and deserves special recognition. It has appeared in a previous Seminar and because of this it is not eligible for earning certification credits; there is no test at the end of this article.
Poison Ivy – Myth and Fact
Edited by Len Phillips
Arborists are in constant threat of exposure to poison ivy. It comes with the job regardless of being a climber or ground operator feeding branches into the chipper. There are a number of myths about climbing poison ivy (Toxicodendron radicans), Western poison ivy (Toxicodendron rydbergii), Eastern poison oak (Toxicodendron toxicarium), and poison sumac (Toxicodendron vernix). Here are some common myths that are followed by the facts.
Myth: Everyone knows what poison ivy, poison oak, and poison sumac look like.
Fact: One third of a million people in the US lose work days every year so they could undergo treatment for a rash from a plant they never noticed. It is important that arborists have photos of these plants, or samples of the plants under glass for all the employees to see. Beside the leaves it is also important to show winter twigs, the stems on tree trunks, and the fruit because they can all cause an allergic reaction.
Myth: You need to touch poison ivy leaves to get a rash.
Fact: This myth is true but you can also get a rash from all parts of the plant from the roots to the seeds. The oil, called urushiol (pronounced oo-ROO-she-ol), can also be passed on to people from tools and
clothes which came in contact with the plants as well as from petting the family dog that ran through the woods.
Myth: You can catch a poison ivy rash by just looking at it or being near the plants.
Fact: This is a myth perpetrated by people who are very susceptible to the rash and make contact with poison ivy while working around it because they do not know what the plant looks like and they never notice it. Direct contact of the urushiol or smoke from burning plants is needed to give a person a rash.
Myth: Poison ivy has red or black fruits and 5 leaflets.
Fact: All four of the Toxicodendron plants have white fruits and bright green, glossy leaves, usually having three leaflets.
Myth: If the oil is washed off, it is no longer a problem.
Fact: The urushiol is so potent, a single ounce can cause a rash on 28 million people. The oil can be blotted hundreds of times and still be potent enough to cause a rash.
Myth: You need to wash the oil off your skin with lots of soap and hot water when you come in from being outside.
Fact: The urushiol can slip through the epidermal layer of human skin in about 5 minutes. After that no amount of scrubbing or treatment will remove it, but removal may prevent the oil from spreading. Within that first 5 minutes, the urushiol can be removed with soap and cold water (which closes the skin pores). Denatured alcohol, hydrogen peroxide, and laundry bleach give temporary relief to the itch, but they dry the skin and this can result in an infection.
Myth: One way to protect yourself is to keep your skin covered when outdoors.
Fact: Partly true, but urushiol can stick to your clothes, which you can touch and spread to your skin later.
Myth: The oil causes redness, itching, and blisters.
Fact: As the body attempts to remove this oil, your white blood cells attack, causing the redness, swelling blisters, and itching 2 days or more after contact.
Myth: Scratching the blisters will spread the rash.
Fact: Scratching the blisters will not spread the rash, but it can cause infection.
Myth: Bad cases of rash can be treated at home if you “tough it out”.
Fact: If the rash is on the face, genitals, or covers more than 20% of the body, contact a physician who will probably prescribe steroids. Do not self-diagnose because some steroids can cause a worse reaction. In some severe cases, the person has become so ill that kidney failure is a result.
Myth: There is nothing you can do if you are exposed to it.
Fact: There are several plants that grow in conjunction with poison ivy that will actually contain solvents to urushiol. These plants include jewel weed, ragweed, garlic, skunk cabbage, and aloe. If you realize you have come in contact with poison ivy, rubbing any of these plants over the infected skin within 5 minutes will eliminate any skin reaction.
Myth: Once you have killed the plant, it can no longer cause a rash.
Fact: Urushiol can remain active in decomposing leaf litter and mulch for up to five years after the plant was cut down.
Myth: Burning the vines gets rid of the plant and oil once and for all.
Fact: The worst cases of rash have resulted from burning the vine and people inhaling the smoke, which causes a massive reaction on the exposed skin and in the lungs. These cases require hospitalization and a physician’s care.
Myth: Poison Ivy should be killed with herbicide.
Fact: It could be a hazard for workers to spray the plants and then to remove the dead vines from the tree. There is also the potential for harm to the trees and the environment if the ivy was treated with a general broadleaf weed killer.
Myth: All animals and humans are susceptible to urushiol reaction.
Fact: Actually, everyone is immune to poison ivy at birth but they develop the allergy after one or two exposures as children. Three percent of the general population has retained their immunity despite repeated exposures. Animals and pets are immune but they will carry the oil on their fur which is then transferred to humans if they touch their fur. Browsing animals can chew the leaves without effect. In fact some municipalities have hired goats to clean out the poison ivy from parks and woodlots that have become overgrown with ivy. Goats actually find the ivy to be a treat and will eat the poison ivy first, before anything else in the woods. Just don’t pet the goat’s fur when they are done for the day.
Myth: There is no place to go in the U.S. where you can avoid poison ivy.
Fact: You can move to Nevada, Alaska, Hawaii, deserts, and elevations above 4000 feet. You can also learn to identify the plant and leave it alone.
The two most important Facts: “Leaves of three, let it be!” or “Leaflets of three … beware of me!”
Sources
The following article has been selected because it is deemed very important to the arboricultural profession
and deserves special recognition. It has appeared in a previous Seminar and because of this it is not eligible for earning certification credits; there is no test at the end of this article.
Poison Ivy – Myth and Fact
Edited by Len Phillips
Arborists are in constant threat of exposure to poison ivy. It comes with the job regardless of being a climber or ground operator feeding branches into the chipper. There are a number of myths about climbing poison ivy (Toxicodendron radicans), Western poison ivy (Toxicodendron rydbergii), Eastern poison oak (Toxicodendron toxicarium), and poison sumac (Toxicodendron vernix). Here are some common myths that are followed by the facts.
Myth: Everyone knows what poison ivy, poison oak, and poison sumac look like.
Fact: One third of a million people in the US lose work days every year so they could undergo treatment for a rash from a plant they never noticed. It is important that arborists have photos of these plants, or samples of the plants under glass for all the employees to see. Beside the leaves it is also important to show winter twigs, the stems on tree trunks, and the fruit because they can all cause an allergic reaction.
Myth: You need to touch poison ivy leaves to get a rash.
Fact: This myth is true but you can also get a rash from all parts of the plant from the roots to the seeds. The oil, called urushiol (pronounced oo-ROO-she-ol), can also be passed on to people from tools and
clothes which came in contact with the plants as well as from petting the family dog that ran through the woods.
Myth: You can catch a poison ivy rash by just looking at it or being near the plants.
Fact: This is a myth perpetrated by people who are very susceptible to the rash and make contact with poison ivy while working around it because they do not know what the plant looks like and they never notice it. Direct contact of the urushiol or smoke from burning plants is needed to give a person a rash.
Myth: Poison ivy has red or black fruits and 5 leaflets.
Fact: All four of the Toxicodendron plants have white fruits and bright green, glossy leaves, usually having three leaflets.
Myth: If the oil is washed off, it is no longer a problem.
Fact: The urushiol is so potent, a single ounce can cause a rash on 28 million people. The oil can be blotted hundreds of times and still be potent enough to cause a rash.
Myth: You need to wash the oil off your skin with lots of soap and hot water when you come in from being outside.
Fact: The urushiol can slip through the epidermal layer of human skin in about 5 minutes. After that no amount of scrubbing or treatment will remove it, but removal may prevent the oil from spreading. Within that first 5 minutes, the urushiol can be removed with soap and cold water (which closes the skin pores). Denatured alcohol, hydrogen peroxide, and laundry bleach give temporary relief to the itch, but they dry the skin and this can result in an infection.
Myth: One way to protect yourself is to keep your skin covered when outdoors.
Fact: Partly true, but urushiol can stick to your clothes, which you can touch and spread to your skin later.
Myth: The oil causes redness, itching, and blisters.
Fact: As the body attempts to remove this oil, your white blood cells attack, causing the redness, swelling blisters, and itching 2 days or more after contact.
Myth: Scratching the blisters will spread the rash.
Fact: Scratching the blisters will not spread the rash, but it can cause infection.
Myth: Bad cases of rash can be treated at home if you “tough it out”.
Fact: If the rash is on the face, genitals, or covers more than 20% of the body, contact a physician who will probably prescribe steroids. Do not self-diagnose because some steroids can cause a worse reaction. In some severe cases, the person has become so ill that kidney failure is a result.
Myth: There is nothing you can do if you are exposed to it.
Fact: There are several plants that grow in conjunction with poison ivy that will actually contain solvents to urushiol. These plants include jewel weed, ragweed, garlic, skunk cabbage, and aloe. If you realize you have come in contact with poison ivy, rubbing any of these plants over the infected skin within 5 minutes will eliminate any skin reaction.
Myth: Once you have killed the plant, it can no longer cause a rash.
Fact: Urushiol can remain active in decomposing leaf litter and mulch for up to five years after the plant was cut down.
Myth: Burning the vines gets rid of the plant and oil once and for all.
Fact: The worst cases of rash have resulted from burning the vine and people inhaling the smoke, which causes a massive reaction on the exposed skin and in the lungs. These cases require hospitalization and a physician’s care.
Myth: Poison Ivy should be killed with herbicide.
Fact: It could be a hazard for workers to spray the plants and then to remove the dead vines from the tree. There is also the potential for harm to the trees and the environment if the ivy was treated with a general broadleaf weed killer.
Myth: All animals and humans are susceptible to urushiol reaction.
Fact: Actually, everyone is immune to poison ivy at birth but they develop the allergy after one or two exposures as children. Three percent of the general population has retained their immunity despite repeated exposures. Animals and pets are immune but they will carry the oil on their fur which is then transferred to humans if they touch their fur. Browsing animals can chew the leaves without effect. In fact some municipalities have hired goats to clean out the poison ivy from parks and woodlots that have become overgrown with ivy. Goats actually find the ivy to be a treat and will eat the poison ivy first, before anything else in the woods. Just don’t pet the goat’s fur when they are done for the day.
Myth: There is no place to go in the U.S. where you can avoid poison ivy.
Fact: You can move to Nevada, Alaska, Hawaii, deserts, and elevations above 4000 feet. You can also learn to identify the plant and leave it alone.
The two most important Facts: “Leaves of three, let it be!” or “Leaflets of three … beware of me!”
Sources
- Carlson, Chris, “Poison Ivy”, City Trees, January 1993
- Iles, Jeff, “Leaflets of Three”, City Trees, July/August 2000.