Hunt County Master GardenersTexas A&M AgriLife Extension Service

Poison Oak and Ivy

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Poison Oak and Ivy by June Morgan

It happens every spring. An enthusiastic gardener bent on cleaning out weeds and vines overtaking the shrubbery and fences ends up with a noxious itching and blistering rash which makes him miserable for days, even weeks. The likely culprit is one or both of the plant pests, poison ivy and poison oak which deliver the stick-to-the-skin resin urushiol.

The best defenses are identification and prevention. The appearances of poison oak and ivy have several things in common, one being the tell-tale three leaves on a woody stalk. However, leaves of the oak vine occasionally have 5, 7, or even 9 leaflets. They strongly resemble oak leaves with toothed or deeply lobed edges. In the fall, they will turn red/orange and in the Spring white-green flowers appear which turn to round fruits in summer. The fruits of the ivy vine are grapelike clusters of tiny white seeds with an off-white or pale yellow rind and the leaf edges are smooth or slightly toothed. Needless to say, birds eat these fruits and seeds, compounding the problem of control. Leaves of the same variety often present differing appearances according to their geographical area, so it is wise to find pictures of the poison vines and their non-poisonous relatives.

A hiker roaming through the woods can easily find himself walking through a knee deep patch of these pests as well as brushing against a large tree hosting an ivy vine as thick as one’s arm.  Hand removal of the vines must be done very carefully with lots of skin protection and deep digging. In addition to plastic gloves and cloth coverings, a protective cream(Ivy Block) and a skin oil remover (Tecnu) is available at many drug stores. Once exposure is known, within 5 minutes pour a mild solvent such as rubbing alcohol over the area, then wash with plenty of cold water. Dogs, shoes, and tools must also be decontaminated to keep from spreading the oil. Both the stumps and leaves can be sprayed with one or a combination of several chemicals: glysophate (Roundup, etc.), triclopyr(Spectracide], or 2-4-D and dicamba. Read the directions carefully in order to apply at the correct times and amounts.

The dermatitis caused by the oleoresins of the vines can be quite serious. The misery can cause loss of work, sleeplessness and in some cases, hospitalization. Besides an anaphalactic shock reaction, extreme pain and possible fatality can occur when inhaling the smoke of burning vines. DO NOT EVER BURN THE POISON VINES!

Old and standard treatments for uroshiol dermatitis usually consist of calamine lotion and oatmeal baths, but the victim often wants something stronger. Steroids by injection or cream or a jewelweed preparation will probably give faster relief.  The fluid from the blisters will not cause a spread of the rash, but any remaining resin on the skin or involved objects can do so.

REMINDER: Identify, protect, remove, and never burn!

Nature’s Revenge

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Nature’s Revenge by PJ LaRue Smith.

Several species of poison ivy are listed under the Toxicodendron Mill. (Poison Oak) Genus, a member of the Sumac family.  In the Hunt County area, the predominate type is eastern poison ivy.  This form can be present as a low (6 to 18”), spreading “carpet” on the forest floor, as a climbing vine, or as a bush.  All parts of the plant contain the allergy-producing chemical urushiol, with the heaviest concentrations located in it’s root system.  Depending upon a person’s sensitivity, poison ivy dermatitis (rash) can appear anywhere from a few hours to 7 to 10 days after contact with the urushiol oil.

Poison ivy can be found growing in the woods, along fence rows, and in the yard.  It can sprout from seed (waxy white clusters of berries), aboveground vines, rhizomes, and root crowns.  Seeds are dispersed by animals and birds, and, as they are buoyant, via waterways as well.  Birds and animals partial to poison ivy berries are also fans of hackberry, juniper, Virginia creeper, and blackberries as well.

Many myths abound when it comes to poison ivy.  Myth – Poison ivy is contagious: Fact – Urushiol is an oil, remaining on clothes, shoes, tools, etc. and transferrable until removed with soap and water.  Myth – One can “get” poison ivy by simply being near the plant:  Fact – Urushiol must come in contact with the skin in order for dermatitis to occur. This can happen through direct contact with the plant: secondary contact with an object, person, or animal that has been in contact with the plant; and airborne contact due to burning the plant or during mowing, weed-eating, etc.  (Note: For those who are highly susceptible to the affects of urushiol, smoke inhalation can result in a life-threatening situation requiring immediate medical assistance.)  Myth – Don’t worry about dead plants, they are harmless:  Fact – Urushiol oil can exist on a surface, including dead plants, for up to five years.  Myth – Someone who has “rolled in poison ivy” with no allergic reaction is “immune”:  Fact – Upwards of 90% of people are allergic to urushiol, the number of times exposed and the length of exposure are key factors in developing the allergy.

Protecting oneself from coming into contact with urushiol has several components.  Educating yourself on what the plant looks like in ALL seasons is the first element.  One of the first to leaf out in the spring, poison ivy is also one of the first to turn orange or red in the fall.  Check out the vines growing up that tree you’re about to lean on – does the vine have fine hair-like roots growing from it (poison ivy) or is it smooth (grapevine)?  Are the leaves in sets of three (poison ivy) or sets of five (Virginia creeper)?

Prepare for potential exposure by wearing long sleeves, boots, socks, pants, gloves, glasses/goggles when hiking or doing yard work.  Products, such as Ivy Block®, create a barrier between skin and oil, however, taking a shower after exposure is still required to prevent urushiol transference to other objects or unprotected skin.

The longer urushiol remains on the skin, the greater the potential for reaction. If exposure is likely, follow these steps to minimize the risk of an allergic reaction: 1. Wash all tools thoroughly with soap and water.  2. Remove all clothes, shoes/boots, gloves, sunglasses, belts, cell phones, etc. in the garage, or mudroom (wash everything with soap and water before using/wearing again).  Wash hands in soap and water, then head to the shower.  Poison ivy washes, such as Tecnu®, can remove urushiol that has been absorbed into the skin.  Soap and water will remove oil that remains on the surface of the skin.

It is essential that everyone follow these procedures in a household, even when not allergic themselves, in order to protect those in their family (and visitors) that are sensitive to urushiol.  Vehicles are also a vector of contamination, and should be washed down accordingly as well.

If a reaction does occur, seeking medical attention as quickly as possible will shorten the time of discomfort.  Once a person has become sensitized to urushiol, each subsequent exposure will result in a swifter, more pronounced allergic reaction.  Taking precautions can certainly make “nature’s revenge” less vengeful!