Summer is a great time to explore Wisconsin’s rich natural resources. When you camp, bike or hike, you may encounter diverse trees, shrubs or vines, but none are as easily recognizable as “poison ivy” (Toxodendron radicans) with its distinct three leaflets.
Poison ivy, native to North America, is a perennial woody vine but can also have variable growth habits, from being an upright shrub or a creeping groundcover in its early stage. It is a common pesky plant found in pastures, roadsides, fence rows, wooded forests, beaches and parks.
Poison ivy has distinct alternate compound leaves with three leaflets, where the middle leaflet is slightly larger in size and attached to a short stalk. Generally, the leaflets are oval shaped with pointy tips, with variable margins and textures (serrated, even, lobed, shiny, dull or hairy). In late summer, poison ivy produces clusters of whitish berries and its seeds are spread by birds through droppings.
The plant is noted for its toxic resinous oil called urushiol, causing severe itching, inflammation or blisters on the skin. The entire plant, including its roots, leaves and stems, can secrete the urushiol oil.
Generally, urushiol is a colorless oil, but it can have a slight tinge of yellow in main stems and roots. The oil has strong adherence and can spread through garden tools, clothing materials, boots or even pets that have been in contact with the plant. Urushiol can remain active even on dead plants and roots for two years, and any attempt to burn the dead plants can risk releasing the toxic vapor, causing severe allergic reactions.
To prevent poison ivy injury, get a positive identification of the plants on your property and mark off the section that contains a large population of then. Young boxelder seedlings (opposite leaves) and Virginia creeper (five leaflets) can be easily confused with poison ivy. Always wear a long-sleeved shirt and long pants with boots when spending time in the poison-ivy infested area.
Isolate the contaminated clothes, including gloves and boots, after working in the infested area and wash them in hot, soapy water. Use wipes to clean gardening tools that may have come in contact with the plant.
If exposed to the urushiol oil, wash the infected skin in running cold water immediately. Avoid using complexion soap, as it tend to spread the oil on the skin. Poison ivy cleansing products (like Tecnu skin cleanser, Poison Ivy scrubs) can help remove the oil from the skin with four to eight hours after exposure.
Magnesium sulfate can also help to detoxify the oil and ease the itching. It is best to apply preventive lotions (like Ivy Shield, Ivy block lotion) while working in a known infested area to minimize the risk of poison ivy effect on skin.
Always wear long, thick, water-proof rubber gloves when treating and handling poison ivy plants. The use of herbicides containing active ingredients like glyphosate (Roundup) and triclopyr (Brush killer) are effective in controlling poison ivy. Spot treat the young plant on less windy days or cut the main stems of the shrub or woody vine to the ground and paint the stump with concentrated herbicide. Fall treatment is effective in controlling poison ivy. Always read the product label for its safety and use instructions.
Do not put the poison ivy brush materials into your regular compost pile. It is best to bag the brush, label it and put it in the trash. Do not burn the brush pile.
After removing the brush, clean the infested ground for any leftover poison ivy berries, leaves, stems and roots. The oil can still remain active in the soil surface even after the cleanup and it is best to avoid exposing the contaminated soil surface by adding layers of clean wood chip mulch on the site.