It’s officially summer now and most of us finally have all of our gardens planted, and our biggest concern right now is keeping the crops weeded as they grow. Most vegetable plants can tolerate a few weeds without experiencing major yield loss, but the weeds in an ornamental garden are too numerous. It is a question of economy against aesthetics. Of course, some weeds are worse than others in our gardens, but some of the worst weeds are found far from the garden. One weed that I have worked hard to eliminate from my immediate yard, by the roadside and in the nearby forest, is poison ivy.
Poison ivy is a vine or shrub native to North America that belongs to the cashew family, which also includes pistachio, poison ivy, poison oak, and mango. The sap of mango plants as well as the rind of the fruit contain urushiol, which is poison ivy toxin. Exposure to just 50 micrograms of urushiol, which is equivalent to less than a grain of table salt, causes a rash in 80 to 90 percent of adults, according to the National Institute for Safety and Health in Canada. CDC work. It is indeed a powerful poison. Anyone who peels mangoes should wear gloves.
It grows far too profusely in most of the United States and southern Canada to be suitable for me. It can be found in all of the continental United States except one. Oddly enough, this state is California, but poison ivy grows there quite abundantly. Poison ivy grows particularly well in disturbed sites. It seems that the more human activity there is at a site, the more likely it is to find poison ivy. Parking areas along roads, streams, swimming spots, hiking trails or picnic sites are often the most heavily colonized by this aggressive weed.
Poison ivy typically grows like a vine climbing tree trunks, or just as often, sprawling on the ground in sun or shade. It is quite easy to recognize the growth on the trunk of a tree, or other structure by the characteristic hair like the ties that hold the vine against the trunk. Sometimes poison ivy vines can get quite thick. I’ve seen poison ivy vines as thick as my neck grow 50 feet or more to the trunk. But the plant can also form an upright bush, if it has no support to climb on and it can even look like a stunted shrub.
The leaves of poison ivy are brilliant green and can be irregular, some egg-shaped and others lobed, each of the three leaflets usually measuring no more than 2 inches long. Some look a lot like oak leaves, but they always come in threes with two leaflets directly opposite each other and one leaflet above the pair. In the fall, it has a pretty yellow or red color and the larger plants produce hanging white berries which are appreciated by wildlife. It is sometimes confused with the Virginia creeper but the Virginia creeper has leaves with five lobes. Poison ivy only grows in swampy areas and it is not a vine at all. I have never seen poison sumac in this area. The common sumac we see along the roads with fluffy stems and red berries is staghorn sumac, which is harmless.
The tissues of all these plants contain urushiol, which looks a bit like carbolic acid. Simply touching or brushing the vine or leaves will not usually produce a rash. The plant must be bruised or damaged in some way to “leak” the toxic sap. Hand weeding without gloves is a safe way to contract it. Some people have got the rash on their hands just by taking off their shoes after going through a thick layer of poison ivy. People can be poisoned by contact if the oil remains on their skin, boots, gloves, etc. The toxin can remain potent for a year or more.
Once the rash begins, the pus-filled and itchy rashes are not themselves a source of infection. The poison ivy toxin lasts for at least a year, and even dead vines on firewood can still infect someone. Animals that ride on them can also infect their owners when they get home.
The best way to fight poison ivy is to learn to recognize the vine in all seasons and to avoid it. Spraying it with a weed killer at this time of year may just stunt the current growth and it will come back with even more vigor. Applications of glyphosate in late fall (October) are quite effective.
There is no way I can eradicate poison ivy from my property, but at least I can keep it far enough away from my house that I don’t have to worry about a visitor’s child or dog there. penetrates.