Weed of the Month: Eastern Poison Ivy

Common name: Eastern Poison Ivy
Scientific name: Toxicodendron radicans (L.) Kuntze (Rupr.) Herder

Life Cycle: Perennial
Origin: North America
Poisonous: Severe skin irritant to sensitive humans

Eastern Poison Ivy

Eastern Poison Ivy

Eastern poison ivy inhabits much of the eastern United States. It is a woody perennial that can grow as a low shrub, trailing vine, or climbing vine. As a climbing vine it can grow several yards high and often reaches into the tops of trees. It grows in a wide range of habitats such as pastures, fence rows, and forest edges.

Poison ivy roots are fibrous from a taproot (the main root that grows vertically downward) and long subterranean rhizomes (rootstocks). Aerial roots on vines are frequently noticeable. The vines are woody and light brown or grayish. The easiest identifying characteristic is a trifoliate (having three leaves) compound leaf with shiny leaflets that can be 2 to 4 inches in length and are pointed at the tip. Leaves turn a bright red or reddish-yellow in the fall. The plant produces greenish to grayish-white berries in late summer to early fall. Reproduction is by seeds, rootstocks, and stems that root when they come into contact with the soil. Berries are spread by birds.

All parts of the poison ivy plant, both live and dead, contain urushiol oil and can cause acute dermatitis (inflammation of the skin) to humans sensitive to the oil. Fumes from burning poison ivy plants might also transmit the oil. Animals such as cats, dogs, and horses are not sensitive to poison ivy, but can transfer the oil to humans.

Poison ivy plants in pastures usually grow low to the ground, and mowing is not an effective control tactic. Cutting the vines and removing plants from fences or trees also does not offer long-term control since the poison ivy plant will regrow from root buds or rhizomes. The most effective control is by herbicidal sprays. Several herbicide products are available for poison ivy control. Consult your local Cooperative Extension Service personnel for herbicidal control in your area.

William Witt, PhD, a researcher in the department of plant and soil sciences at the University of Kentucky, provided this information.


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Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.