Killing poison sumac requires several herbicide applications and diligent attention to new plant growth. Also known as poison elder or poison dogwood, poison sumac (Toxicodendron vernix) is an innocuous-looking shrub or small tree that can reach 25 feet if left unchecked. All parts of the tree contain urushiol, an oily toxin that can cause severe dermatitis within 12 to 24 hours. Poison sumac is a tough plant, so killing it will take patience and determination.
Before you remove poison sumac, protect yourself by wearing long pants, a long-sleeved shirt, and boots. Wear plastic gloves under your garden gloves or wear rubber gloves to ensure that no toxic oils seep through the fabric. Putting a barrier cream containing 5 percent bentoquatam on your hands at least 15 minutes prior to exposure will provide additional protection. If your bare skin still comes into contact with the tree, wash the affected area thoroughly with soap and cold water, and then wash again with rubbing alcohol. Rinse off with cold water. If you apply herbicide, wear protective eyewear. Avoid leather gloves and boots, which absorb herbicide.
You can attack the foliage by spraying the tree with an herbicide containing glyphosate as the active ingredient. May through July, when the tree is in bloom, is the most effective time to spray. Mix 2 1/2 ounces of glyphosate with 1 gallon of water and spray with a pressurized handheld sprayer so that all leaves are evenly coated. Do not spray so much that herbicide is dripping off the leaves. You can also coat leaves individually with a sponge or paintbrush. Follow label instructions exactly, and take care not to get herbicide on nearby plants, since glyphosate will kill desirable plants. You may need to spray multiple times throughout the growing season to kill the tree. Remove and dispose of any dead or dropped leaves.
For larger trees, it may be more practical to saw the plant down using a handsaw. Saw the tree close to the ground, so that there is a stump about 1 or 2 inches long remaining. The Alabama Cooperative Extension recommends using an undiluted glyphosate product with 20 percent herbicide, or a 41 percent glyphosate product diluted by half with water, to paint the stump. Use a small amount—a pint or quart should suffice. Apply herbicide with a foam paintbrush or handheld sprayer. Wrap the top portion of the tree in a garbage bag and dispose of it, along with any dropped leaves. Check the stump periodically for new growth and if you see any, reapply the herbicide.
For maximum benefit, apply the glyphosate solution as soon as you cut the sumac down. This lets the herbicide work before the plant starts to seal off the wound.
Considerations and Concerns
Never burn poison sumac, because the smoke can be extremely irritating to the lungs. Store unused herbicides in a safe place where they cannot be accessed by children or pets. There are many non-poisonous species of sumac in the United States, so make sure you identify the tree correctly before you attempt to kill it. Poison sumac can be found in U. S. Department of Agriculture plant hardiness zones 2 to 9, where it prefers moist, swampy conditions. It is similar in appearance to staghorn sumac (Rhus typhina), which grows in USDA zones 4 to 8. Staghorn sumac has dark red berries and pointed leaves, while poison sumac has grayish-white berries and smooth, oval-shaped leaves.
- The Texas Department of Insurance: Poison Ivy, Oak and Sumac Fact Sheet
- National Gardening Association: Toxicodendron Vernix
- Floridata: Rhus Typhina
- Alabama Cooperative Extension: Cut Stump Herbicide Treatments for Invasive Plant Control
- Honey Bee Suite: Master Plant List
- U.S. Forest Service: Herbicide Mixing Cheat Sheet
Michelle Wishhart is a writer based in Portland, Ore. She has been writing professionally since 2005, starting with her position as a staff arts writer for City on a Hill Press, an alternative weekly newspaper in Santa Cruz, Calif. An avid gardener, Wishhart worked as a Wholesale Nursery Grower at Encinal Nursery for two years. Wishhart holds a Bachelor of Arts in fine arts and English literature from the University of California, Santa Cruz.