POISON IVY

If it’s February and you are itching and trying not to scratch, a condition I’m unfortunately too familiar with, you may have contacted poison ivy (Toxicodendron radicans). Having recognized in early childhood that I was super-sensitive to poison oak/ivy, I learned to identify and avoid that plant. I thought. I confused it with Virginia creeper for a while but did overcome that problem. Since that time, I have essentially been on a search-and-destroy mission.
Here are some points to remember if you want to join me in my quest:

  • Leaves of three, let them be. Berries white, run in fright. This saying doesn’t always eliminate all danger. All parts of the plant-leaves, vines, roots-at any stage-dormant, active, dead-contain the sap or oil which on contact with an allergic person results in a painful, itching dermatitis. Therefore, you should always be careful when cutting, pulling, or burning if there is a possibility that poison ivy is involved. Animals that run through or over poison ivy can transfer it to you by direct contact with paws or fur.
  • Avoid contact if allergic. Duh! I frequently see this warning in information and articles regarding poison ivy. After the initial exposure, who would do this? My point is that wearing protection is WISE. Be safe and wear long sleeves tucked into gloves, long pants tucked into socks or boots. There are currently some barrier creams and lotions that can be applied prior to possible exposure and that have been proven effective. Soaps specific for post exposure are also available. Washing with lots of water as soon as possible after contact can reduce the risk of contracting the rash.
  • Home remedies aren’t much help. It takes about two weeks for the rash to clear. If you have a serious reaction, you should contact a doctor.
  • You don’t outgrow the allergy.

Enjoy your time in your garden this spring and summer, but be careful of poison ivy/oak.

Ragna Neill, former Smith County Master Gardener
Texas AgriLife Extension


POISON IVY AND POISON OAK

“Leaves of three, Let them be”

At an early age my mother taught me the old saying, “Leaves of three, let them be.” After I came in contact with poison ivy and ultimately experienced excruciating pain from a rash and itchy blisters, I knew what she was talking about. The same saying can also apply to poison oak. They both cause inflammation of the skin when you come into direct contact with the vines’ irritant oil. Here are ways to help you identify these dreaded plants:

Poison Ivy: It comes in a vine or shrub form. Each branch on this plant has a cluster of three shiny leaves that do look like ivy leaves. In early spring the leaflets are reddish and become reddish orange in the fall. Poison ivy produces white berries.

Poison Oak: As with poison ivy, poison oak has three green leaves in a cluster. Its leaves look similar to oak tree leaves but have rough edges. Like poison ivy, the leaves are reddish in the spring and turn reddish-orange in the fall. Poison oak also grows as a vine or shrub and produces white flowers.

Using weed eaters or lawnmowers and burning the poison ivy or oak spreads the plant’s irritating oils, therefore never burn these plants. The best way to get rid of them is through chemical applications.

There are products that can be applied to the skin before going outside that will help eliminate skin irritation to the oils. There are other products that can be used after exposure but before the blisters form that will remove the oils from the skin. If you do not have either of these, upon contact wash the affected area with cold water to help remove the irritant from the skin. Do not use warm or hot water.

Jim Powell, Smith County Master Gardener
Texas AgriLife Extension


If you haven’t ever had poison ivy, poison oak or poison sumac, consider yourself very lucky so far. In medical terms it’s ‘contact dermatitis’, a condition in which the skin becomes itchy, red, sore, inflamed (rash) after direct contact with the clear, sticky, oily, resin like substance called urushiol,(you-roo-shee-ol), found in all parts of the plant including the leaves, stem, root and fruit.

Within fifteen minutes of contact the urushiol binds to skin proteins. It then penetrates the top layer of skin to bind to the cells deep in the epidermis. If it is washed off with soap and water before that time the reaction may be prevented. After the antigen is fixed, however, it cannot be washed off or transferred to other areas. Once it’s bound to cell membranes urushiol is virtually impossible to wash off. While attached, it is a warning signal that attracts the body’s T-cells and starts a full blown immune response.

The rash spreads to other parts of the body only by direct contact with anything that has the urushiol on it such as dead leaves, rake handle, gloves, clothing, including your belt, door handle, pet, steering wheel, computer keyboard, or when it may be airborne such as lawnmowers, trimmer, or the smoke from burning poison ivy.

A specimen of urushiol several centuries old can still cause a rash in some sensitive people. One to five years is normal for urushiol to remain active on any surface including dead plants. Only one nanogram (one billionth of a gram) is needed to cause a rash. One hundred nanograms is an average dose. One fourth ounce of urushiol is all that is needed to cause a rash on every person on earth. Five hundred people would itch just from the amount covering the head of a pin!

Prevention is the best approach to these pesky plants. So wear gloves when working, and wash any exposed areas with soap and water immediately after contact. Decontaminate by removing and washing all clothing, shoelaces etc. that may have come in contact with the oil. Try not to scratch as it may cause infection. There are many products that moisturize the skin and decrease the itching, and one product that even states it can even unbind the urushiol from the cell membrane. The itching of poison ivy usually lasts about two weeks but if it lasts longer, or if blisters, weeping and oozing, or tenderness occurs you need to notify your doctor in case there is any infection or allergy.

Poison Ivy and Oak are identified by three leaflets attached at the center and leaflets may be smooth or serrated edged but not lobed. Poison Sumac has seven to 13 leaflets.

Rita Christenot, Smith County Master Gardener
Texas A&M AgriLife Extension Service

Posted in Pests and Pesticides