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YARD AND GARDEN: Poison ivy, cashews, mangos and pistachios are cousins!

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Coles County Master Gardner Kathy Hummel shares these little known facts about poison ivy:

Are you one of the estimated 85% of people have some type of allergic reaction to poison ivy? The culprit is a clear liquid called urushiol found in all parts of the plant, which is responsible for the itchy, blistering reaction. However, there are ways of keeping this nasty vine under control.

Poison ivy is a shapeshifter: It can take on different appearances. The leaves might have slightly scalloped edges, or the edges may be smoother. Leaves are slightly glossy and grow in clusters of three. Color can range from green to reddish.

It can grow as a vine, a small bush or as small plant. It can climb a tree as a hairy vine or blend in with other plants on the ground. Translucent white or cream-colored berries remain on the plant throughout winter and spring. Follow the old saying: “Leaves of three, let them be. Berries of white, run in fright.” Virginia creeper has many of the same attributes, except it has five leaves in each cluster.

Before you wage war, the first thing you need to do is protect yourself. Since the poisonous urushiol is in every part of the plant, it would be best to wear gloves, long pants, long sleeves, etc. If you’re highly sensitive, a mask and goggles wouldn’t hurt.

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What kills poison ivy? Goats will happily clear out patches of poison ivy without any itchy side effects, but if you know of any goat-rental services in Coles County, please let me know. Vines rely on the strong root system to keep them alive. If you cut them, anything above the cut will die.

You can spray the leaves with a systemic herbicide such as glyphosphate or brush killer. The herbicides are absorbed through the leaves and are transmitted to the root system, killing the plant. The spray will kill any plant it lands on, so be careful to spray only the poison ivy. Follow the label directions.

Pour the mixture into a spray bottle. Set the sprayer to stream (not mist) for better control. Be careful where you spray because it will damage any leaf that it hits. This is not a systemic remedy and will take longer to see results. Be patient. Keep in mind, continually spraying salt in the same area can add too much salt in the soil and will damage all plants.

Dead vines of poison ivy still contain potent amounts of oil so do not burn it! The smoke can inflame your lungs, bronchial tubes, nasal passages and eyes. If you are exposed, according to the FDA, you should quickly (within 10 minutes):

  • First, cleanse exposed areas with rubbing alcohol.
  • Next, wash the exposed areas with water only (no soap yet, since soap can move the urushiol around your body and actually make the reaction worse).
  • Now, take a shower with soap and cool water. (Hot water opens your pores.)
  • wipe tools you used with rubbing alcohol and wash your clothing separately from other clothes. The oil can remain active for over a year.

Friday Freaky Fact: Cashews, pistachios and mangos are in the same family as poison ivy, poison oak and poison sumac. They all contain powerful chemical irritants known as anacardic acids. So, handling and eating raw cashews and pistachios will cause the familiar itchy skin reaction in people sensitive to the chemicals. The mango plant contains the acid, but not the fruit itself.

Why isn’t there a reaction when people eat processed cashew nuts and pistachios from the grocery store?

The irritants are found in the shell oil, but not in the nuts themselves. Roasting at high temperature destroys the shell oil, so commercially sold nuts will not trigger a reaction.

Eradicating poison ivy takes requires protection, maybe some goats, herbicides and patience. Be persistent and careful.

If you have questions about your garden or landscape, go to Be sure to visit U of I Extension’s horticulture website and LIKE the Master Gardeners’ Facebook page

Illinois Extension leads public outreach for University of Illinois by translating research into action plans that allow Illinois families, businesses, and community leaders to solve problems, make informed decisions, and adapt to changes and opportunities.


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