Poison sumac (Toxicodendron vernix) is a woody perennial plant that grows in damp and swampy wooded areas in eastern North America. Also known as thunderwood or swamp sumac, the genus name translates to "poison tree" in Greek. Poison sumac contains the same toxin, urushiol, that is found in poison ivy and poison oak. Of these three species, poison sumac contains the highest concentration of toxic urushiol; all parts of the plant are toxic to humans and animals. If you find this plant on your property, you'll want to get rid of it—whenever you find it.
Poison sumac is an extremely tenacious plant that can resprout if even small portions of the rhizomatous roots are left behind. No matter what method is used, it might take more than one attempt to achieve complete success—and you might find yourself using several different methods. Continue to keep an eye out for the plant, as it is quite common for poison sumac to return.
What Is Poison Sumac?
Poison sumac is a native North American woody shrub or small tree that can grow as much as 30 feet tall. Often found growing at the base of a larger tree, poison sumac is most prevalent in damp, swampy, or boggy areas in the Southeast, Midwest, and Northeast U.S. Poison sumac has compound leaves, each with seven to 13 oval, pointed leaflets with smooth edges. The plant's stems are red, and its leaves are green in the summer and yellow to red in the fall. It has green berries that turn white in the fall and grow in small clusters on individual stems. These smooth-edged leaves and white berries—and its fondness for moist soils—are the features that distinguish poison sumac from most other sumac species. "Safe" sumacs generally have red berries, toothed leaf margins, and are likely to be found in dryer soils, such as hillsides.
Plants that contain urushiol—such as poison sumac, poison ivy, and poison oak—should not be treated lightly. While a handful of people are lucky enough to be unaffected by this toxin, roughly 90 percent of all people will experience some reaction to urushiol oil as it oxidizes. This can range from simple itching to extremely painful weeping blisters. In extreme cases, even life-threatening allergic reaction is possible, though this happens only in rare instances of actual oral ingestion or breathing smoke from plants that are burned. And just because you don't have an immediate reaction doesn't mean you are safe—it can take a week or more for slow skin absorption to result in a serious allergic reaction.
Here are some preventive measures you can take to avoid serious reactions to these plants:
- Wear long sleeves, boots, protective eyewear, and gloves whenever you are in an area where poison sumac is suspected—and always when you are handling it. The goal is to prevent any skin contact from occurring.
- Before working with poison sumac, use a lotion containing bentoquatam, an over-the-counter skin-care product that can prevent urushiol from being absorbed through the skin.
- Never burn any part of a poisonous plant such as poison sumac. Skin rash can develop if you are in contact with the smoke, and if you breathe contaminated smoke, life-threatening reactions are possible.
- After working with poison sumac, immediately wash your clothes, then clean the washing machine to eliminate any traces of urushiol.
- Urushiol can remain on surfaces for up to five years, so thoroughly clean any tools you use to remove poison sumac, using rubbing alcohol or soap and water.
Should you contact poison sumac or another of the plants containing urushiol, immediately clean your skin with soap and water to eliminate the oils and minimize skin absorption. During this time, take special care not to touch your eyes, face, genitals, and other sensitive parts of the body.
If you start to experience itching, redness, rashes, or blistering, then treat the areas using wet compresses, calamine lotion, hydrocortisone cream, or an antihistamine cream such as Benadryl. In most cases, symptoms will last no more than one to three weeks, but if symptoms persist—or if you experience throat swelling, trouble breathing, or a noticeable fever—then seek medical attention.
Equipment / Tools
- Protective clothing
- Rubber gloves
- Pruning shears
- Garden hose
- Pump sprayer
- Trash bags
- Flattened cardboard, newspaper, old carpeting, or tarps
- Herbicide for woody plants
How to Remove Poison Sumac by the Roots
One organic method to get rid of poison sumac is to pull it out by the roots. The roots must be disposed of in the trash, not composted or burned.
Pull the Plant Away From Growth and Structures
Wearing protective clothing, including boots and rubber gloves, pull the plant away from any surrounding growth and structures. Trim it back to the ground with pruning shears. If the plant is mature, its limbs could be intertwined with foliage and structures nearby. Use your shears to free it, and then bag all the clippings.
Spray the Area
Spray the area with a hose to saturate the soil. Wait about 30 to 60 minutes to allow the water to soak in. This will make it easier to pull up the roots.
Dig and Pull
Using a shovel, dig around the root ball, prying it up from underneath. Then, with gloved hands, pull all the roots from the soil, and place them in a plastic garbage bag. Dispose of the bag as recommended by local authorities.
How to Smother Poison Sumac
Smothering entails cutting the sumac plant close to the ground and then covering the stems with newspaper, cardboard, old carpeting, or tarps. However, even after you kill the plant, it will remain toxic. So be careful when disposing of the plant and its roots after removing the smothering material.
Trim the Plant
Using pruning shears, trim the plant to the ground. Discard the trimmings in a plastic garbage bag.
Cover the Ground
Next, take cardboard, a tarp, or another smothering material, and cover the ground where the plant once lived. Take care to cover the surrounding area where roots could throw up new shoots. Spread mulch over the smothering material, and let it sit for at least one growing season.
Dig Up the Roots
After at least one growing season has passed, uncover the area and dig up the roots using the same precautions you would for a live poison sumac plant. Discard the roots in a plastic garbage bag.
How to Remove Poison Sumac Using Herbicide
As a last resort, you can use herbicide to effectively get rid of any poisonous plant. If you're using herbicide, understand that it might kill wanted garden plants if sprayed indiscriminately. Herbicides are best applied on calm days with a sprayer that allows you to carefully target the application.
Read label directions carefully, as not all herbicides do a good job of killing poison sumac. Glyphosate is a very common broad-spectrum herbicide that will kill poison sumac. But rather than diluting it with water as is usually done when using glyphosate on grasses or broadleaf weeds, poison sumac calls for the herbicide to be used at near full strength. Follow label directions for using the product on woody plants such as sumac.
Choose a Sunny Day
Herbicide eradication works best on sunny days with a temperature over 70 degrees Fahrenheit and little wind. Make sure there is no rain in the forecast that will wash off the chemical before it kills the plant. Don't spray if rain is predicted within 24 hours of treatment.
Prepare the Herbicide
Prepare your herbicide according to the package directions. Some products might need to be mixed with water inside a pump sprayer, but the concentration may be quite different when used on a woody plant such as poison sumac. In other cases, the manufacturer may recommend painting on the undiluted herbicide at full strength. Always wear protective clothing when you're handling herbicide.
Spray the Plant
It's ideal to spray the poison sumac when it's fully leafed out. This means going after it during the height of its growing season, which is generally late spring to mid-summer. If the sumac limbs have engulfed a tree, carefully apply the herbicide onto the leaves to avoid damaging the tree with overspray.