Identification of Poison Ivy Through Sensing Patches

Use "Ivy Alert" as an Aid in Identifying Poison Ivy

Poison Ivy
  Cyndi Monaghan / Getty Images

Proper identification of poison ivy (Rhus radicans) is essential for outdoorsy types if they wish to avoid ending up with an itchy rash. Elsewhere you can find poison ivy pictures as a visual aid for your identification work; it certainly makes sense to consult those pictures first, so that you'll have a good idea of what this weed looks like before you even come close to it! But thanks to a product named, "Ivy Alert," it is no longer necessary to rely on pictures alone.

Identification of Poison Ivy: Science to the Rescue

The Ivy Alert product comes in the form of a kit (small enough to carry in a large pocket). The key component of the kit is a sensing patch that detects urushiol, the oil in Rhus radicans responsible for the rash. According to the makers of Ivy Alert, the product generates "a color change to black in response to physical contact with urushiol. This color change is the result of a simple, reliable chemical reaction between the urushiol and the product's reagents and solutions." 

How to Test for Poison Ivy With Sensing Patches

The sensing patches are sticky on one side; you get 15 of them in the kit, and you peel them off a cardboard backing. The product's directions show a patch being applied to a shoe, but you could apply a patch to just about any object (not your skin, though!). Also in the kit is a little bottle of "surfactant solution," plus some swabs.

  1. Sprinkle some of the solution on the sensing patch you're trying out, to activate it.
  2. After you suspect the sensing patch has made physical contact with Rhus radicans, it's time to put your suspicions to the test. Apply a drop of the solution to a swab, and rub the swab on the test patch.
  3. If you then observe the formation of a black residue on the patch and/or on the swab, it means that you have, indeed, encountered urushiol.
  1. Immediately wash any skin area that you may have inadvertently brought into contact with the weed (directly or indirectly), as well as tainted shoes, clothing, garden tools, etc. (they can harbor urushiol).

Identification of Poison Ivy: Is It Foolproof With the Patch?

In a word, no. If your patch doesn't test positive, it doesn't mean you haven't come into contact with Rhus radicans. For those curious about the product's effectiveness for the identification of poison ivy, it may be safer to attach the testing patch to a long pole rather than your shoe. There's no sense in taking unnecessary chances, so keep your distance from those weeds!

In our first attempt at the identification of poison ivy through this product, the patch failed: the weed in question was Rhus radicans, but there wasn't a positive test result. For the second attempt, we applied more surfactant solution to the patch than the directions call for rubbed the patch more vigorously against the weed. The result: a positive test!

Identification of Poison Ivy With the Patch: Bottom Line

The Ivy Alert patch is marketed as a product that you can wear on your shoe to alert yourself to "unexpected exposure" to urushiol. Upon receiving a positive test, you would rush inside immediately to wash off any urushiol that may have landed on your skin.

And, in fact, many folks may wish to use the product in just this way.

However, you may be more interested in using the product as a learning tool for novices in the identification of poison ivy. If you haven't already, obtain a basic idea of what the weed looks like through pictures, then test out your newly found knowledge using Ivy Alert. Thereafter, with your eye schooled in what Rhus radicans looks like, you should be able to avoid it.

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