‘Leaves of three, let it be’

Curtis Young, my counterpart in Van Wert County, recently wrote an article in the Buckeye Yard and Garden online newsletter with the title, “Leaves of Three, Let it Be.”
The complete phrase was drilled into me when a young Scout: “Leaves of three, let it be. Leaves of five, let it thrive.”
“Leaves of three” is referring to the plant poison ivy, Toxicodendron radicans L. Kuntze, which may cause a rash, blistering, swelling and extreme itch in sensitive individuals. Its key identifying feature is a leaf that consists of three leaflets.
Very few plants have three leaflets and poison ivy, by far, is the most common.
Individuals may confuse poison ivy with young boxelder, Acer negundo L., seedlings, which often have three leaflets when small.
However, boxelder leaves and branches grow opposite on the main stem and poison ivy leaves grow alternate on the main stem.
Poison ivy is often found in our area growing in wood edges, fence rows, and along trails. Its widespread dispersal is often the result of birds spreading the seeds in droppings at roosting sites, including in towns.
An oil called urushiol causes the skin reaction. All parts of the poison ivy plant contain urushiol, but most people come in contact by brushing up against the leaves.
However, contact with stems and vines even during the winter may affect sensitive individuals.
The woody vines should not be burned since heat volatizes the oil and the contaminated smoke can get into the eyes and lungs, potentially causing a more serious problem than physical contact.
Dogs and cats do not react to the oil. However, pets running in poison ivy may inadvertently carry the oil on their fur, causing problems to sensitive individuals rubbing the fur.
Poison ivy grows in a variety of forms, including short shrubby plants that grow on the ground and spread by horizontal underground stems, or rhizomes, and vines that climb trees, walls and poles.
Poison ivy produces aerial roots from the sides of its vining stem. These roots attach the vine to other plants and objects such as walls. The aerial roots often give the vines a hairy appearance.
There are other vine-like plants found on trees in the woods, such as grape vine. However, grape has a single leaf rather than three leaflets.
One vine that people often confuse with poison ivy is Virginia creeper, Parthenocissus quinquefolia L’.
Virginia creeper also has multiple leaflets, but typical in groups of five rather than three. Thus the statement, “Leaves of five, let it thrive.” Virginia creeper does not cause skin reactions like poison ivy.
Homeowners often desire to eradicate poison ivy because of its potential for skin irritation.
Because it is a perennial plant, hand removal may require several attempts to remove all plant parts that might regrow.
To lessen the risk of exposure by hand removal, wear long sleeves and chemical-resistant gloves.
Vines growing up objects can be severed near the ground and allowed to shrivel and die. Afterward the root and new growth that it will produce can be more easily managed.
Broad spectrum, non-selective herbicides such as glyphosate (Roundup) or triclopyr (Ortho Poison Ivy & Tough Brush Killer) may be used to chemically control poison ivy.
Since these products are non-selective, care must be taken not to apply to other nearby plants.
Treatments tend to be more effective when applied in late summer or early fall. Repeat applications may be necessary. Clean-up sprays may also be needed again in the spring.
Persistence will be required to eradicate poison ivy. The Extension fact sheet, “Poison Ivy Identification and Control,” has additional information. It may be found at: http://ohioline.osu.edu/hyg-fact/1000/1015.html.
A thanks needs to be given to Curtis Young for permission to use parts of his article.
In the meantime, it is still good advice: “Leaves of three, let it be.”
Lentz is extension educator for agriculture and natural resources for The Ohio State University Extension Service in Hancock County. He can be reached at 419-422-3851 or via email at lentz.38@osu.edu.
Lentz can be heard with Vaun Wickerham on weekdays at 6:35 a.m. on WFIN, at 5:43 a.m. on WKXA-FM, and at 5:28 a.m. at 106.3 The Fox.


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