Tuesday, August 7, 2012

Poison Ivy

One of the most common plants in our woodlands that is often found along paths and can cause distress is poison ivy (Rhus radicans). It has pros for wildlife but cons for people.

If you have ever been a victim of the uncomfortable rash caused by it, you already know the cons. But, there are a few pros. It is a native plant, a source of food for birds, and habitat for many critters that live on the forest floor or in trees.

Poison ivy is a close relative of the pistachio and cashew. It’s one in a family of plants that produce sap caustic to humans. Yet, some people don’t have a reaction at all when exposed to it.

If the oil stays on your skin for more than 10 minutes, even in winter, you can get an itchy rash, which will show up on your skin over a period of 24 to 72 hours, depending on your level of exposure and sensitivity. Although direct contact with the oil or smoke from burning poison ivy is necessary to get the rash, remember that the allergen, urushiol, doesn't become dormant; it remains active for days on whatever it touches, including pets. Pets don’t get a rash, but can get oil on their fur and then rub it onto furniture, rugs, and you. The oil will remain on your clothes.
Poison Ivy
Learn to recognize it. Poison ivy can look like a small shrub, or vine if it’s climbing a tree. The leaves grow in groups of three, usually with a red area in the center where the stems of the leaves meet. They can have smooth edges, be slightly lobed or have an undulating margin. Woody stems are tan and possibly covered with reddish-brown, hair-like aerial rootlets if they're climbing a tree or building.

It might be confused with box elders or wild raspberries, because of their compound three leaflet clusters. Boston ivy might look like poison since its young leaves have a shiny reddish color. These plants are very different. Box elders are large trees; raspberries have thorns, and Boston ivy has a different shape to its leaf. If you’re in doubt, don’t touch it until you get a positive identification.

If you have to work around it, wear gloves, long sleeves, long pants, and keep your socks pulled up. Wash clothes with a strong soap and any areas where it touched your skin with a solvent, such as isopropyl alcohol, as soon as possible.

Getting rid of poison ivy on your property is a slow and steady process. My herbicide of choice is a systemic weed killer such as a glyphosate based product. These are approved for use over tree roots where poison ivy is most commonly found. The herbicide works in about seven to ten days if it’s applied according to labeled instructions. The poison ivy will brown slowly and die, including roots.

It’s important to cut vines near the ground so you aren’t spraying herbicide up into trees. Glyphosate is a non-selective herbicide that will kill any actively growing plant. And, depending on the amount of poison ivy you’re trying to control, a second application on regrowth might be necessary. If dead plants must be removed, wait until they begin to decay.

For more information on poison ivy, check http://poisonivy.aesir.com/view.

©2012 Joel M. Lerner
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