Extension Educator, Horticulture
Every time I work in the garden I emerge with some battle scars. I get a little too close to that raspberry bush or a rose cane jumps out at me. I normally don't worry about it too much and just consider it my red badge of workage. However one spring I emerged with more than just a few scratches. Soon after working in the garden, I developed blisters on my arm reminiscent of poison ivy. But I knew it had to be something else.
I followed the trail of weed carcasses back through my garden, right past a plant called rue. I had heard of people being allergic to rue, but I had never had a reaction previously. Rue is a very common plant in ornamental and herb gardens. It was once used for medicinal purposes. However now it is considered unsafe to use medicinally and has been delegated to be an ornamental. It has lovely small, blue-green leaves and grows to 3 feet tall.
Now I understand why I hadn't had a reaction to rue before. Rue has glands throughout the plant that contain a volatile oil that reacts with the sun (specifically UltraViolet - A) to produce itching, burning, red spots and/or large blisters in some people. The reaction can occur within hours of exposure to the plant and sun. That's the catch - the reaction requires exposure to the sun. The oils in rue seem to be predominantly located on the surface of the leaf so it is easily transferred. In addition, the oils can be transferred to clothing and pets. Some people may get a similar reaction from euphorbias, wild parsnips, cow parsnips, mayweed, gas plant and even celery leaves. Generally the plant's leaves or stems have to be broken to release the oils. Be very careful when mowing ditch banks where wild parsnips and mayweed hang out.
You may decide to eliminate these plants from your garden, or you could work around the rue last to reduce sun exposure, or when working in the garden wear long sleeves and gloves. In addition after working in the garden, immediately wash skin with soap and water. Also wash all clothing in hot soapy water and not with the family wash. If you have questions about plants and skin reactions, please contact your physician.
You may not be able to tell an artichoke from an aster, but poison ivy is one plant you should be able to pick out of a line-up. Poison ivy is a bit different in that the reaction to the oils doesn't require sunlight. Symptoms usually appear within 24 hours, but may appear in a few hours or a few days.
Poison ivy is a woody perennial plant that may grow dwarf and erect or vine through trees or along fences. The birds often deposit seeds in fencerows. You may have heard "leaves of three, let it be". The leaves are alternate on the stem and are divided into three oval shaped leaflets which are pointed at the tip, tapered at the base and may be lobed or toothed. The terminal leaflet is longer stalked than the two side leaflets. In the spring the leaves are tinged in red.
According to the booklet Pesky Plants by Thor Kommedahl, the reaction of the poison in poison ivy with the skin is nearly instantaneous. However, immediately washing with strong soaps or rubbing alcohol can remove any excess poison that might be transferred to other parts of the body. I like to take moist towelettes when I'm hiking just in case I get attacked by another plant.
Saturday May 28 at 11:00 am Bug-Geta Raymond Cloyd, U of I Extension specialist, How to effectively deal with insects in the garden.