Poison-ivy (Toxicodendron radicans) is a native woody, perennial vine. Though it doesn’t pose the same problems that other common weeds do, it has its own significant pest quality.
At a recent Master Gardener meeting it was noted how much poison ivy we were seeing.
“Poison-ivy (Toxicodendron radicans) is a native woody, perennial vine. Although it doesn’t pose the problem in terms of nutrient and water competition that a majority of other common weed species do, it has its own significant pest quality,” Penn State Extension Educator Timothy Abbey posted.
“My guess is that you are all aware of it. All parts of poison-ivy contain resinous compounds called urushiols. When urushiols contact the skin, or are inhaled, they cause inflammation, itching, and blistering,” Abbey said.
Master Gardener Jerry Lewis had also noted it and wrote up a post about it.
“I was driving from home to Newville yesterday, and was struck by the amount of poison ivy I was able to pick out along the road as I drove along. I have found more poison ivy growing in my yard this year than ever before, so it’s time to send out a warning: be on the look-out!
“Poison ivy comes in several forms: a trailing vine, a small shrub, or as a climbing vine,” Lewis noted. He provided just a couple of highlights from the University of Connecticut's Integrated Pest Management site:
- Compound leaves have three leaflets on a leafstalk with two leaflets on opposing sides and the third alone at the stalk end. Leaflets can be lobed, smooth, toothed or have hairy undersides. The stems are woody.
- Poison ivy can grow in the open, in deep shade, or along pathways and roadways.
- Spring foliage is reddish and shiny. Flowers appear in a green cluster and fruit is white and waxy like mistletoe. Summer foliage can be dull or glossy green while fall foliage is yellow, red or orange.
- Urushiol, the toxic substance for us humans, is in the stems, leaves, fruit, flowers and roots. It is present in all plants at all times of the year in about the same strength. It is released by any bruising of any of the plant parts. Skin contact usually causes an allergic reaction. It can contaminate people indirectly by contact through clothing, garden tools, pets, or by inhaling smoke from a fire where it is burnt. Urushiol remains potent for a couple weeks; longer if the weather is dryer.
- Penn State’s Abbey also added in his post “You don’t even have to contact the plant directly. The liquid can get on tools, pets, or clothing and when you touch them, you can pick it up. It can also be inhaled when it becomes a gas when poison-ivy is burnt. Dead plant material contains the urushiols, too. Nasty stuff!”
- Symptoms - itching, burning, swelling, rash with watery blisters - appear hours to several days after exposure. A person cannot contract poison ivy from touching the actual rash or fluid from the blisters. It cannot spread from one part of the body to another. However, urushiol can remain on skin or clothing or a pet's fur, and be then transferred to another person.
- Control is often difficult. You must dispose of the entire plant for it to be effective. Cut vines and pull them away from trees. Dig up roots. Mow or cut young shoots until the plant dies. Do not burn the poison ivy, but dispose of it where it cannot contaminate people or animals. Cover as much skin as possible with protective gloves and clothing. Clothing and tools should be cleaned to prevent the spread of urushiol.
“Use caution when eradicating this weed,” Abbey said. “Poison-ivy reproduces primarily from seed that is dispersed by birds when they eat the fruit. It can also spread from the root stock and stems that can root to surfaces, such as a tree trunk. Poison-ivy is a vine that grows vertically as it attaches to various structures, but it also becomes a ground cover when it can’t grow upwards. Leaflets are in groups of 3 and can be smooth, toothed or lobed. This is different from another common native vine, Virginia creeper, which has leaflets in groups of 5. The foliage turns red in the winter.
One option for managing poison-ivy is the use of goats. Goats love to eat this plant! Is this a practical option for most of you? I would guess no, but seriously consider it if the situation lends itself to their use. Herbicide options are limited to glufosinate-ammonium (Finale) as a foliar burndown application. This active ingredient does not translocate. It may not kill larger plants, which may be hard to treat in their entirety.
Glyphosate (Roundup and others) can be applied to foliage, or to the vine via cutting and squirting/wicking into the wound. The “glove of death” can also be used for precise foliar application. If you are not familiar with this method, put on a chemical resistant glove (nitrile and some rubber ones can be used) then put on a fabric or cotton glove. Apply concentrated glyphosate on the outer glove then touch the plant.”
Lewis found that The Wall Street Journal reported on a study that leaf size and oil content of poison ivy is much higher since the 1950's. So let's say one good thing about poison ivy: since poison ivy absorbs more CO2 as its leaves become larger, maybe it is helping to combat climate change.