Poison Ivy is a well known plant pest. It can be found in Florida by landscapers, public maintenance workers, naturalists, homeowners and visitors to the Sunshine State. For many persons, touching this plant or its relatives will result in skin rashes. Being able to identify this plant is a first step in avoiding poisonous plant problems and is a first step in successfully eliminating this weed from the landscape. Information for today’s column was compiled from University of Florida sources for a training program for city maintenance workers.

Relatives of poison ivy include edible plants such as the mango, pistachio, and cashew, the invasive exotic Brazilian Pepper Tree, and native plants such as the sumacs and Poisonwood. Some people have sensitivity to many of these plants. Therefore, if you get a rash from poison ivy, be careful with mangos and when chopping out those problematic Pepper trees from your yard.

Poison Ivy is given the botanical name Toxicodendron radicans, although some literature still refers to it as Rhus radicans. It grows as a high climbing woody vine that can live for many years. The stem produces aerial roots that allow the vine to cling to upright surfaces. At maturity, the vine can grow up the trunk of trees, palms, walls and other upright structures. A common place plant in woody areas, our office gets frantic calls from homeowner and professionals alike when cabbage palms are moved from the wild into the landscape without consideration for the vines than can be found growing from the soil that is moved with them.

The appearance of this plant is quite variable in leaflet shape. Most people have head of the adage: "leaves of three, let them be." Poison ivy leaves actually consist of three leaflets. Each individual leaf is made up of three large shiny leaflets which each measure from two to four inches long and are pointed at the tip. Poison Ivy is sometimes confused with other multiple leaved plants. One common look-alike is the native Virginia creeper, which has five leaflets .

Small yellowish green flowers appear in the spring and grow in clusters from the lower leaf axils. Fruits are seed-like, with a soft fleshy part covered with a skin-like outer layer that surrounds an inner seed. Mature fruit are ¼ inch in size and grayish white in color. The fruit of Poison Sumac, which is not native to our area, is also whitish in color. The Sumacs in our area have red fruit, and are relished as a wildlife food source.

TOXICITY OF POISON IVY RELATIVES

The toxic principle in these plants is a phenolic compound called urushiol. It is a skin and mucous membrane irritant and is found in all parts of the plant. Some humans are quite sensitive to the effects of the toxin while others show no ill effects from coming into contact with the plant. The toxin has little or no effect on animals, but pets may carry the irritating substance on their hair and thereby transmit it to humans.

Susceptible humans exhibit intense itching with inflammation and the formation of blisters at the areas of contact. Animals are rarely affected. Burning of poison ivy plant parts may be dangerous because the irritant may be transmitted by smoke. Extremely sensitive persons should locate those that are not susceptible to the effects of the toxin when removal of these plants from unwanted sites is required.

Persons who anticipate exposure to these plants should wear appropriate clothing to limit exposure. Long pants and long sleeve shirts, fully enclosed shoes, with leather or canvas gloves are suggested. If vines or branches are to be removed from places high in trees, protective eye wear and an appropriate hat should be worn as well. Avoid brushing up against the plants as much as possible during removal operations.

Protective clothing should be removed as soon as practical after exposure to these plants. Do not mix these clothes with other clothes as the irritating oil could be transferred to unaffected clothing.

If accidental exposure to poison ivy occurs, a ten percent water solution of potassium permanganate is usually effective if applied within five to ten minutes after exposure. It should be followed by repeated washes with soap and water to remove the oily sap.

There are many other products sold to relieve the symptoms of the irritating rash after it develops, but there is one new medication that should be investigated by sensitive persons. Lotions and creams containing the active ingredient bentoquatam will find that when properly applied before exposure to poison ivy, the symptoms may be eliminated.

WEED REMOVAL

Removal of poison ivy and its relatives from the site is the most appropriate method to prevent skin reactions and poisoning. Removal of these plants by use of hand cultivation and pruning may be attempted if the size of the plant is not large, if the labor force is not fully sensitized to the toxic material contained in the sap, and if the extensive use of herbicides would jeopardize desirable ornamental plants that are growing close to this weeds.

Herbicides can be used directly on poison ivy foliage when growing along fences or on other landscape features, and some granular herbicides can be used as a follow up for longer control. However, most of these pesticides will also injure or kill desirable trees that harbor these vines. Cutting the base of a tree-climbing vine and promptly applying an appropriate herbicide to the cut surface of the vine can control resprouting.

Choose a herbicide only after reading the pesticide label. At the time of this writing, some of the recommended herbicides used to control poison ivy relatives include the following herbicides: 2,4-D, glyphosate, imazapyr, triclopyr. Some of these products are labeled for use in only in specific sites, and pesticide registrations change over time. Check with your county extension service for the most current herbicides recommendations from the University of Florida.

If you need additional information on Poison Ivy, visit your county Master Gardeners, or call or stop by your county Extension office. For those with other questions about Florida Yards, contact me - my phone number is 863-763-6469 and you can send e-mail to dfculbert@ifas.ufl.edu.

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Trade names, where used, are given for the purpose of providing specific information.  They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. Florida Cooperative Extension Service / IFAS /University of Florida. Larry A. Arrington,  Dean.  Last update: 07/13/2006 .  This page is maintained by Dan Culbert