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poison ivy

Weeds That Make You Itch: Poison Ivy, Poison Oak, and Poison Sumac

March 20, 2018

Almost all gardeners consider poison ivy, poison oak, and poison sumac as weeds in the landscape, despite their sometimes-lovely fall color! While researching this article, I discovered there is far more discussion of these plants in medical sources than in the horticulture world. Gardeners only want to know how to avoid contact with these plants!

What makes you itch?
The “poison” in these plants is urushiol, a toxic oil found in roots, stems, leaves, flowers, and seeds! Contact with oil that clings to your tools, clothes, shoes, your pet’s fur, dead plant parts, or is released by burning can all cause skin reactions. Beware of roots left on trees, especially if you are cutting firewood, which can expose you to that oil in the dead of winter inside your home!

Identifying the plants
Urishiol gives all of these plant leaves a dull, waxy sheen that helps in identification. The saying “Leaves of three, let them be” actually refers to the three leaflets that typically make up these plants’ compound leaves.

Here in Western North Carolina, you’re most likely to encounter poison ivy (Toxicodendron radicans), which can grow as a climbing vine, a low spreading vine, or as a shrub. Its stems often look like fuzzy rope going up a tree. In fall, it has bright red leaves and white or cream berries.

Poison Ivy_cygnus921_CC BY 2.0_Flickr
Poison ivy, three leaflets
Poison ivy vine_Kerry Wixted_CC BY 2.0_Flickr
Poison ivy vine growing up tree trunk
Poison Ivy_Fall 2013_Deb Watson_CC BY-NC 2.0_Flickr
Poison ivy, fall color on bushy plant

Poison oak (Toxicodendron pubescens) is found in the North Carolina coastal and Piedmont regions, but not in the mountains. It grows as a vine or a shrub, but has leaves that look more like oak leaves, typically—but not always—with three leaflets.

Poison Oak (Toxicodendron diversilobum)_Jerry Kirkhart_CC BY 2.0_Flickr
Poison oak, shiny new leaves emerge in spring
Poison oak_Toxicodendron pubescens_by NCSU Extension
Poison oak, doesn’t climb like poison ivy
Poison Oak_Linda Tanner_CC BY-NC-ND 2.0_Flickr
Poison oak, three leaflets

Poison sumac (Toxicodendron vernix) is the least common of the three, but is found throughout North Carolina—although rarely above 4,000 feet in the mountains. It grows as a shrub or small tree with 7 to 13 leaflets on each leaf stem.

Poison sumac_Anna Hesser_CC BY-NC-ND 2.0_Flickr
Poison sumac, shrub with berries
Poison sumac_NCSU Extension
Poison sumac, ovate leaflets on leaf stem
Poison sumac_Toxicodendron vernix_John Barber_CC BY 2.0_Flickr
Poison sumac, fall color

Control
Wear long sleeves, long pants, shoes, and gloves when working around these plants. Wash with soap and water when you are done, and promptly wash clothes worn for this job!

Learn to recognize small seedlings and pull immediately. Plastic newspaper bags used as a “glove” provide a long sleeve over your arm that can be peeled off and turned inside-out to contain seedlings and small plants for easy disposal. When pulling larger plants, be sure to get the roots. Bag all plant material for removal. To rid large areas of poison ivy, you may need to use an appropriately labeled herbicide when the plants are actively growing. Brush killer is usually recommended. Most often more than one application will be required. Remember that dead plants will still retain oil, so plan to dispose of these, too!

Article written by Joyce Weinberg, Extension Master GardenerSM Volunteer.

More information
Welcome to the World of Poison Ivy, Poison Oak, and Poison Sumac
http://www.poison-ivy.org

Poison ivy (Toxicodendron radicans) plant description
by NC State Extension

Poison oak (Toxicodendron pubescens) plant description
by NC State Extension

Poison sumac (Toxicodendron vernix) plant description
by NC State Extension

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Categories Weeds Tags poison ivy, poison oak, poison sumac

It’s time to attack Poison Ivy!

July 21, 2014

 

Poison Ivy

Along with many other weeds, Poison Ivy has really taken off this year, and many gardeners are faced with “Now what do we do?” The major point now is not to let any of it go to seed, and beyond that here’s a list of options:

Goats: Not practical in every situation but can be effective.

Weeding or hand pulling of the whole plant, including the roots: Effective but again not practical for many of us.

Flame: Works for many weeds but NOT FOR POISON IVY! Breathing the smoke is extremely hazardous!

Foliar spray of a chemical herbicide: From midsummer into fall, before the leaves turn color: Glyphosate, triclopyr, dicamba and 2-4,D are the most commonly available in garden centers. These are the active ingredients listed in small print on the front of the container. Read and follow the label directions. Add a sticker or surfactant if called for to help the chemical adhere to those shiny leaves.

Cut stump treatment: For major vines that are climbing trees, cut the vine and immediately treat the stump with a concentrated herbicide. Use a spray, brush, sponge or wick. The best time for this approach is late winter into summer when the plant is actively growing, not now. In many cases, and depending on how long the problem has been growing, the control project will be more than just a one-shot deal. For example, the NCSU bulletin on poison ivy suggests severing the vine that has grown up a tree as step one, followed by poisoning the stump and perhaps mowing the shrubby part to the ground so the live plants may be more easily treated with an herbicide.

Bottom line: The sooner a problem plant is recognized the easier it will be to handle.

Again: Don’t let any of these bullies go to seed. “One year seeding means eight years of weeding!”

Poison Ivy in Autum
Poison Ivy Stem on Tree Trunk

Article written by Glenn Palmer, Extension Master Gardener Volunteer.

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Categories Weeds Tags goats, herbicides, pest control, poison ivy

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