Poison ivy is a weed that affects almost every gardener and outdoor lover in Georgia.

It is found in nearly every outdoor environment, and most folks can tell you not so fondly of the after-effects of a poison ivy encounter.

It is important that people working and playing outdoors know how to identify, treat and control this poisonous weed.

Poison ivy is a woody perennial plant belonging to the cashew family.

It grows as a small shrub or as a climbing vine on trees, fence rows and buildings.

It has compound leaves with three bright green, shiny leaflets. These leaflets can have smooth, toothed or lobed margins. The upper leaf surface is smooth, and the leaf undersides commonly have hairs.

However, poison ivy leaf shapes are variable. Some plants may have different leaves on the same plant, or different leaves on poison ivy vines close by. To be cautious, always follow the saying "leaves of three, let it be."

All parts of poison ivy - including leaves, stems, fruit, flowers and roots - are poisonous at all times of the year.

When skin contacts poison ivy, symptoms can include inflammation and blistering. An oily compound called urushiol is responsible for allergic reactions. This chemical can be carried over to humans by contact with equipment and pets exposed to poison ivy. Humans can also be exposed to urushiol through soot particles from burning poison ivy.

Allergic reactions to poison ivy vary between individuals. It may take anywhere from 12 hours to a few days for symptoms to arise from contact with poison ivy toxin.

After exposure, you may wash your skin with cold water within five minutes, or soap and water within the first 30 minutes. Wash clothes to avoid transfer of the toxin to household furniture.

Several products, such as Tecnu and Ivy Block, can be used to prevent or lessen allergic reactions after supposed exposure.

Poison ivy can be controlled in the landscape by several means. It will not tolerate repeated mowing, so any vines encroaching on your lawn shouldn't last for long. Small poison ivy plants can also be dug out by the roots in small ornamental and garden beds. Just be sure to wear waterproof gloves.

There are numerous chemicals available to control poison ivy. Vines have an extensive root system, so it may take multiple sprays to completely control. Glyphosate, the chemical in Roundup and many other brand names, can be highly effective on poison ivy. It needs to be applied to an actively-growing plant. You need to be careful using glyphosate around other landscape plants because it is non-selective and will injure most any plant.

Another effective product is 2,4-D. It often comes in formulations mixed with other chemicals, such as dicamba and triclopyr. This chemical also needs to be applied to actively-growing vines. Some people like 2,4-D because it will not injure most grasses. When using this chemical, beware of spray drift that could injure landscape or vegetable plants.

Triclopyr is another chemical used to control poison ivy and other large woody vines. A common use of triclopyr is as a cut stump treatment. The undiluted chemical can be "painted" on freshly cut stumps to control regrowth. In some situations, repeat applications will be needed. Use cautiously around desired landscape and garden plants.

Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.