Poison ivy is an unwelcome plant on many Texas properties, and a Texas A&M AgriLife Extension Service expert has some tips on how to avoid and remove the pest plant that causes a painful rash.
William M. Johnson, Ph.D., AgriLife Extension horticulturist, Galveston County, said removing poison ivy is worth the effort to reduce the risk of exposure.
“Poison ivy is one of those plants that nobody wants to be around—much less have on their property,” he said. “If you’ve ever had a reaction or known someone who has, you know that it’s worth the time and money to effectively remove it.”
Poison ivy and other pest plants
Poison ivy is most identifiable by remembering – “Leaves of three, let it be.” Poison ivy plants display three leaflets at the end of each stem. Mature leaves are 2-4 inches long, dull or glossy green with relatively smooth, rounded edges and pointed tips.
The plant spreads underground via rhizomes, Johnson said. Birds and other wildlife eat the berries and spread it secondarily through droppings.
It can present itself in many ways according to its environment, Johnson said. It is a tall climbing vine that will attach to other plants, trees, a fence or any structure that supports growth. But it can also grow along the ground or as a shrub.
The plant prefers semi-shady areas with moist, rich soil, but can survive in most any environment, Johnson said.
“Poison ivy can survive just about anywhere,” he said. “But it loves woody areas and can be a real problem along walking trails or even in raised beds in home gardens.”
Johnson said poison oak is closely related and looks very similar to poison ivy and both plants produce urushiol – the cause of the rash, blisters, and infamous skin itch.
Poison ivy and poison oak are often confused with several other vining-like plants like peppervine and Virginia creeper, he said. Poison oak is more prevalent in East Texas, whereas poison ivy can be found throughout the state.
“Identifying poison ivy or poison oak is important because the consequence of mishandling them can be painful,” he said. “But none of these vines are preferred plants on any property.”
I touched poison ivy, now what?
Urushiol is a highly concentrated and stable oil, Johnson said. One billionth of a gram can irritate a person’s skin. Just 1/4 ounce of urushiol is all that is needed to cause a rash in all 7.8 billion people on earth if every person were sensitive to urushiol.
Urushiol can also bind to pet hairs or gardening tools and maintain potency for long periods of time.
Many people aren’t sensitive to urushiol, but it can cause horrible rashes for people with poison ivy sensitivity, Johnson said.
“I am not sensitive to it, but I am careful to avoid contact with poison ivy, because I know people can develop sensitivity to it as they age,” he said. “I don’t tempt fate and practice the ‘better safe than sorry’ approach.”
If the oil gets on your skin, you have about 15 minutes before it bonds to your skin, so immediate treatment is recommended, he said.
Johnson recommends running generous amounts of water over the area until it is gone. If rubbing alcohol is available, pour it over the area first as alcohol readily dissolves the oil, and afterwards follow with ample amounts of running water.
“Soap can work, but it can also work against you by spreading the irritating oil,” he said. “So, I recommend starting with rubbing alcohol as a solvent and following with cool running water because hot water will open your pores. Don’t scrub because that can spread it, just let the water run over it, lots of water, until it’s gone.
“After that, take a shower with soap and warm water,” he said. “Then wash the clothing you were wearing when exposed to urushiol. If this sounds like a lot of time and effort, be assured it will be worthwhile considering the pain caused from the skin rashes.
Best way and time to treat poison ivy
Johnson said catching poison ivy early can reduce the time and effort it takes to eradicate the plant.
If your property was poison ivy-free but you see the tell-tale three leaves emerge in the spring, he said the best strategy is to manually remove it. Wear suitable protective gloves, like Neoprene or Laytex, and a long-sleeve shirt that will prevent the oil from touching your skin when removing plant material.
“If it’s just one or a few sprouts, just dig them up with a spade,” he said. “Make sure you get all the roots and dispose of it in the trash. Don’t burn it because the oil that causes the skin irritation will vaporize, and the worst case of poison ivy is when it gets in your lungs. Wash the spade with soapy water in case some urushiol oil was deposited on the shovel. ”
Treating established poison ivy is a bit more involved, Johnson said. It could take multiple applications of multiple herbicides to fully eradicate the plant.
Spraying the plant foliage with an herbicide containing glyphosate as the active ingredient, such as Round-Up, or triclopyr, such as Brush-B-Gone, or a combination of dicamba plus 2,4-D, will be effective. Two weeks before or after full bloom, which is typically in late-spring or early summer, is the best time to spray because the plant is absorbing liquid and nutrients to grow.
Applying herbicide at any other time will give decent control, he said, but will not fully eradicate the plants in one run. Using a combination of the herbicide options in alternating treatments could improve effectiveness.
Do not apply herbicides on windy days to avoid spray drift onto non-target plants in your landscape or your neighbors’ landscapes, Johnson said. And always read and follow label instructions.
“Glyphosate can be effective anytime, though air temperatures and soil moisture levels do impact herbicide effectiveness,” he said. “The 2,4-D is good for early summer and spring, whereas the triclopyr is best after the leaves fully spread in the spring or fall. Just be persistent because the poison ivy is only going to spread and get worse.”
Climbing vines already established in trees can be cut near the ground, he said. The stump should be treated with an herbicide immediately to maximize absorption. Make cuts to the vine horizontal to allow the herbicide to sit and soak.
The vine can be physically removed carefully or left to wither, he said.
“Even when the vine dies, the urushiol oil can be a problem, so be careful anytime you’re handling plant material whether it is fresh or dried,” he said.