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 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 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.
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
