With the warming of temperatures, the greening of grass, and the start of the majestic botanical display we know as spring there also comes the concern of poison ivy. Poison ivy is a woody vine with compound leaves comprised of three leaflets. The margins of the leaves may be either smooth toothed or lobed. Leaf margins are sometimes a source of confusion for people when attempting to identify poison ivy. That is why multiple identification methods are recommended. The plant produces clusters of small, green flowers in June or July. The fruit are small, white berries. Many bird species use the seed as a food source, and thus spread seed to new areas.
Poison ivy grows in a variety of habitats, but is most commonly found on the edges of wooded areas. Plants may occur as erect shrubs or as vines climbing trees, fences, or buildings. The vines produce aerial rootlets that tightly attach to structures. In addition to seed, the plant reproduces by creeping rootstocks. The spreading roots can extend for several yards from the parent plant.
A commonly mistaken plant for poison ivy is Virginia creeper. Unlike poison ivy, Virginia creeper has five leaflets in a cluster making it easy to distinguish from poison ivy. A common myth in Iowa is that one can be infected by poison oak. There is on poison oak in Iowa as its presence is limited to the west coast.
Poison ivy is responsible for more that 2 million cases of skin poisoning each year. The toxin causes inflammation and swelling, accompanied by painful irritation and blisters. Symptoms usually occur within 12-24 hours after contact with the plant, but sometimes may not appear until 3-4 days after exposure.
The toxin is an oily compound present in all parts of the plant. The toxin retains its potency even after plants have been killed. Therefore, it is important to dispose of all plant refuse after destruction. The oil can be carried on clothing, tools, pets, and in smoke. Therefore, burning is not a recommended method of plant refuse destruction.
Most people do not respond to the toxin the first time they contact the plant, but they become more sensitive with repeated exposures. Sensitivity to poison ivy varies among individuals, and children are usually more susceptible than adults.
Poison ivy can be controlled either mechanically or chemically. Only individuals with a high tolerance to poison ivy should be involved with control and destruction of plants. Seedlings can be controlled by mowing and physical removal; however, established plants require repeated mowing due to the resprouting from the established rootstocks.
Two major types of herbicides are recommended in controlling poison ivy, glyphosate (roundup, kleenup)and growth regulators such as 2, 4-D, 2, 4-DP, dicamba, and triclopyr. Products containing 2, 4-D or triclopyr are generally more effective on woody plants such as poison ivy than 2, 4-D or dicamba. For more information on wild plants or other items, contact us at 319-334-7161, email at xbuchanan@iastate.edu or at our website at www.extension.iastate.edu/buchanan