Poison Ivy

Introduction

One of the hazards of working or playing in the outdoors is contact with poison ivy and having to endure the discomfort of the allergic reaction associated with the plant. Therefore, it is important to recognize poison ivy so that such contact may be avoided, or appropriate measures be taken to eliminate the plant from the home landscape.

How to Recognize Poison Ivy

See a detailed description and photos of poison ivy in UMass Extension's Weed Herbarium.

“Leaflets three, let it be.” That old saying sums up the most easily identified characteristic of poison ivy - its three leaflets. The middle leaflet of the three tends to be larger than the two on either side, but each measures from 2 to 4 inches in length. At maturity, the leaflets are dull or glossy green. New leaf shoots in spring tend to be droopy and reddish green in color while in fall, the leaflets turn a vivid orange or red color. The edges of a leaflet may be irregularly toothed, smooth, or lobed.

Poison ivy is a perennial plant and can be found in different forms. It may grow as a low, spreading shrub with fine stems. It may also grow as an upright, three foot tall shrub, or it may grow as a woody vine. Vines attach to tree trunks by way of aerial roots that make the vine look like a fuzzy rope.

In spring, poison ivy produces clusters of small yellow-green flowers that originate in the axils of leaves. Later in the season, small (three-sixteenths inch diameter) gray to white berries appear. The berries are eaten by birds and other animals who help disperse the seed.

Where Poison Ivy Grows

Poison ivy can be found throughout Massachusetts. It grows along roadways, fence lines, stone walls, woodlands and stream banks and may even appear among shrubs and perennials in the home landscape. It is adapted to a wide range of soil and moisture conditions.

Reactions to Poison Ivy

The “poison” in poison ivy is an oil called urushiol. Found in resin ducts in all parts of the plant, urushiol is released whenever the plant is crushed or bruised. When the oil contacts skin, it can cause an allergic reaction, ranging from reddening and swelling, to blistering or open sores. Reactions will vary depending upon the sensitivity of the individual to urushiol.

Contrary to popular belief, the rash caused by poison ivy, is not spread by contact with open sores. However, the tacky oil is persistent and can be spread indirectly by contact with pets, garden tools, garden gloves, shoes, golf balls, or any other object that has come in contact with a bruised poison ivy plant.

Furthermore, the oil persists in dormant and dead plants. Poison ivy should never be burned since the smoke can carry the oil and cause severe problems to anyone inhaling the smoke. Wood cutters using a chain saw to cut logs with attached poison ivy vines have been known to suffer serious allergic reactions when inhaling urushiol that was volatilized during the cutting process.

After contacting poison ivy, the affected area of skin should be washed immediately with soap and cool water - warm water may hasten skin penetration of the oil. Consult a physician or te ointment or medication if the allergic reaction is severe.

Controlling Poison Ivy

There are several options for controlling poison ivy in the home landscape. Grubbing or pulling up the plant is easiest in spring or fall when soils are moist. Gloves should always be worn - and handled carefully afterwards - when grubbing. It is important to pull up the entire root since the plant can regrow from segments of root remaining in the ground. Wash gloves and clothing thoroughly after handling poison ivy plants.

Herbicides containing either glyphosate or triclopyr are commonly used for chemical control of poison ivy. Garden centers are a good source for brands or formulations with these herbicides. Check the label carefully to be sure poison ivy is listed among the plants to be controlled and follow the label directions carefully when applying the product.

Typically, an herbicide is applied to actively growing poison ivy, beginning in early summer after the leaves have fully expanded. Thorough coverage of the plant foliage is essential. Where poison ivy is growing among ornamental plants, it is advisable to apply the herbicide to poison ivy leaves using a wick applicator so that the chemical is not inadvertently applied to surrounding plants.

Poison ivy may not be controlled with just one herbicide application. Repeat applications may be necessary.

Written by: Ron Kujawski
Revised: 09/2011