Leaves of three let it be-Is this Poison Ivy?

Published 8:20 pm Friday, August 19, 2022

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When cooler weather comes around like we had over the past week, I want to be outside. I have this itch that tells me I need to go outside and tackle the gardening tasks I’ve been putting off. The other side of this time of year for me is that I want to go hiking to enjoy the onset of fall. When the leaves begin to change in a few months this will be top on my agenda!

One of the issues that comes up this time of year with gardening in our ornamental beds or being in the woods in general, is poison ivy (Toxicodendron radicans). Do you know how to identify poison ivy? I find, through speaking engagements and talking to kids in schools, most folks do not know this plant. The easiest part to look at is the leaf and number of leaves. Poison ivy will compound leaves, this means that leaflets are all attached by a rachis to one long stem (petiole) that is then attached to a main trunk or branch. In the case of poison ivy, it is pinnately trifoliate, meaning it will have three leaflets on this one petiole. The middle leaflet is typically a bit longer than the outer leaflets and attached to the rachis. The outer leaves are typically attached directly to the petiole. Always remember, “Leaves of three, let it be.”

But, wait, there’s more! I had a co-worker who was working on a pier recently and looked up poison ivy to identify it. She said, “I know it wasn’t poison ivy because it had jagged edges and poison ivy is smooth.” This isn’t necessarily a good identifier when it comes to poison ivy. The leaflets can be smooth as described, but they can also be lobed like sassafras or toothed (serrated) like most cherry trees. The leaves can also change color throughout the season. A newly emerged plant will display shiny reddish leaves. Throughout most of the season the leaves will be a shiny green but towards the end of the season they tend to become dull looking. Leaf size is all over the place as well ranging from 2 inches up to 6 inches in length. In the fall, the leaflets turn a brilliant red typically after the first frost.

What is the big deal with poison ivy anyway? These plants contain an oil called urushiol that can cause itching, red rash, and blistering. I had a friend in college that was highly allergic to urushiol. We were in several plant classes together that required field trips to the mountains to identify and learn different species of plants and their culture. Our junior year, he got into poison ivy really bad and had to actually go to the doctor for a shot after our trip. Our senior year, we went to the very same place. He was very careful that year, wearing long pants, socks, and boots while we were hiking and exploring. When we got home however, he had developed the same rash and had to go get the same shot even though he had been so cautious. How? He was covered the entire time except for when he slept in his sleeping bag. But he had not washed his bag from the year before and became infected from the residue that was still on the inside of the bag from the previous trip.

How can you minimize the effects of poison ivy? The first is by knowing what to look for, “Leaves of three, let it be,” is a great start. However, older vines will be growing up the side of a tree not displaying any leaves. In this case, look for the vine to be extremely hairy lending it to another adage, “A hairy vine, is no friend of mine.” Poison ivy can also be in a shrub form, in this instance look again for the leaves of three. The second way to minimize the effects of poison ivy is to personal protective clothing such as long sleeves, pants, socks with shoes, and/or gloves. However, just as my friend learned, these need to be washed thoroughly before being used again or than can still cause a skin rash. Wash your hands, clothing, and tools thoroughly to remove the oil from them. I have had really good success with using an alcohol-based hand sanitizer after coming in contact with poison ivy plants.

What should you do if you get a rash from poison ivy? Wash and soak in cool water, this will be very soothing to the itch. Use over-the-counter products that contain corticosteroid as long as you aren’t allergic to these. There are some other soaps that tend to help with affects such as Zanfel or generics that I have personally found helpful although no research-based information is available to my knowledge to verify this claim. If the reaction is severe, contact your primary care professional as my friend did.

What should you do if you find poison ivy in your landscape? There are many great wildlife benefits to poison ivy! Believe or not, many animals eat the leaves, bees and wasps pollinate the flowers, and birds consume the berries. If it isn’t a direct threat to you or your children, you should leave it alone. However, if it is in a high-traffic area, you may want to take care of it. A product that contains glyphosate or triclopyr or a combination of the two will work really well. In some cases, a follow-up application may be necessary. Always use pesticides according to the label. Removal is also an option albeit a risky one. Make certain to cover up and wash everything completely. Never burn poison ivy after removing it, this may cause a severe reaction from the inhalation of the smoke.

If you are itching to learn more about plant culture or have an issue in your home garden or landscape, send your questions to Gene Fox, Consumer Horticulture Agent with the North Carolina Cooperative Extension Service, please email at Gene at gene_fox@ncsu.edu or call at (252)946-0111. Extension Master Gardeners are available to answer your questions as well. Drop by the Extension Office located at 155 Airport Road in Washington, NC!