Everyone who works outdoors with plants or goes hiking, camping and picnicking should be able to identify poison ivy. Failing to know this plant when you see it can lead to severe allergic reactions.
Poison ivy and its cousins – poison oak and poison sumac – are said to cause more contact dermatitis – redness, rash, blisters and itching – in the United States than all other plants and industrial or household chemicals.
Poison ivy, Rhus radicans, is found mostly in moist, deciduous forests and wooded areas. Unfortunately, it is also found on trees, fences and ornamental plantings in Georgia landscapes.
Poison ivy may grow as a small shrub or a high-climbing vine on trees, fences and buildings. Each compound leaf has three bright green, shiny leaflets. The tips of the leaves on poison ivy are usually pointed. A related species, poison oak, Rhus toxicodendron, has leaves with rounded tips.
Remember the rule: The shape of the leaves and presence of hairs on the undersides vary greatly, so people may not always recognize poison ivy. The old saying, “leaflets three, let it be,” is a good rule.
Poison ivy produces small flowers with five yellowish-green petals arranged on slender stalks. Its small, grayish white berries are food for more than 55 bird species.
Box elder, Acer negundo, is often confused with poison ivy. Its seedlings have three leaflets too, but they have opposite leaves. Poison ivy leaves are alternately arranged on the stem.
Virginia creeper, Parthenocissus quinquefolia, is also commonly confused with poison ivy. However, it is a harmless plant that has five leaflets growing out of one point where they are attached to the vine. Virginia creeper has blue berries. It is found growing in the home surroundings on houses, fences, trees, and in other places where poison ivy is observed.
All parts of poison ivy are poisonous year-round. A toxic, oily compound, urushiol, is quickly exuded if plant tissues are broken in any way. People are exposed as they brush against the plant or touch equipment, clothes or pets that have touched it. It can even be carried in the smoke from burning the vines.
Only the oily toxin, though, can spread the rash. Symptoms usually appear in 12 to 48 hours but may not show up for days. If you think you’ve contacted poison ivy, washing your skin with cold water may keep the urushiol from contacting your skin. Within the first 30 minutes of contacting poison ivy, use soap and water. Consult a physician or pharmacist for the best treatment.
Digging poison ivy plants and roots can control it in small beds of landscape ornamentals. Be sure to wear watertight gloves, though. Continually clipping poison ivy at or near the ground will eventually control it. But you may have to clip it several times during the year for several years.
Herbicides can control poison ivy, too. But always read all label directions. Poison ivy has extensive roots, so you’ll likely have to apply herbicides several times. Glyphosate is the active ingredient in Roundup and many other products. Apply it directly to the foliage of poison ivy. It works well on warm, sunny days when plants are actively growing.
When using a chemical, spray when the plants are flowering or fruiting, generally in early summer in Georgia. You’ll need at least one rain-free hour after applying glyphosate to get the best results. The product can severely injure desirable plants, so don’t spray it on windy days. Use coarse sprays with large droplets to minimize drift.
Where poison ivy has grown into large trees, cut the vine 2 to 3 feet above the soil. Within 24 hours, spray the leaves of the lower section with a strong glyphosate solution, using at least a 41 percent glyphosate concentrate to make the spray solution.
Then paint or spray the top of the cut stem portion with a 50-50 glyphosate-water solution or undiluted glyphosate, with at least a 41-percent glyphosate concentrate.
Triclopyr is another chemical recommended around homes, fences and nongarden areas to control poison ivy. It’s often used to keep poison ivy and other plants from coming back after being cut. As with glyphosate – Roundup – clip the poison ivy vine near the soil surface, then paint the freshly cut surface with undiluted triclopyr. Repeat the treatment if regrowth appears.
Randy Drinkard is the ANR Agent for The University of Georgia Troup/Meriwether County Cooperative Extension. The Troup County Extension office is located at 114 Church St. and can be reached at 706-883-1675. Open Monday through Friday, 8 a.m. to 5 p.m.