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Extension > Garden > Yard and Garden > Weeds > Poison ivy & its control

Poison ivy & its control

 

Poison-ivy (Toxidendron radicans) is a woody perennial shrub or vine that spreads by underground runners and by seeds. It grows in all types of soil and under all conditions of sun and shade.

Poison-ivy can be distinguished from other plants by its leaves which are always divided into three leaflets. It is these which are referred to in the old warning, "Leaves of three, let it be."

These leaves, each consisting of three leaflets, alternate on the stem. Each leaflet is oval-shaped, pointed at the tip, and tapered at the base. The middle leaflet has a longer leaf stem than the two side ones. Leaflets may be slightly lobed or coarsely toothed. When some leaflets are lobed, people may call these plants "poison-oak," but true poison-oak does not grow in Minnesota. There are only variations of poison-ivy.

The leaves' surfaces may be smooth or hairy, glossy or dull. They can vary in color from yellowish-green and green to reddish-green. Poison-ivy fruits, which develop in fall, are small white berries with sunken ribs.

Poison-ivy is best controlled with an herbicide containing triclopyr, a woody brush-killer. It should be applied directly to the leaves of the poison-ivy, not soaked into the ground. When used according to directions, this herbicide should not injure established grasses, only broad-leafed plants.

Apply the herbicide when poison-ivy is growing actively. Temperatures should be in the 60° to 85°F range. Avoid windy days when droplets might drift onto the foliage of nearby trees, shrubbery or garden plants.

You may have to spray more than once since poison-ivy is a tough plant to kill. Wait two weeks or more between applications, and repeat only if weather permits. Don't apply herbicide after poison-ivy foliage begins to show fall color. Wait till new leaves are fully expanded the following spring.

Some resprouting might occur several months later. Watch the area for at least a year and repeat the treatment as needed. As with any garden chemical, read and follow label directions carefully each and every time you use it.

Be very careful cutting down poison-ivy; all parts of the plant are poisonous. Note, too, that even the dead plants are poisonous. Never burn them! Smoke and ash can carry toxins to the skin causing a rash. Inhaling the smoke can be worse.

Poison-ivy may seem difficult to eliminate from your property, but you can do it with consistent, careful and conscientious effort.


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Reviewed 3/99

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