By far the most troublesome plant encountered by homeowners in the Texas landscape is the poison ivy (Toxicodendron radicans) in its various forms. Although all parts of the plant are toxic and capable of causing skin irritation, not everyone experiences problems. Sensitive individuals, however, must exercise extreme caution if they live in an environment where poison ivy may be present. Encounters such as running over leaves with the lawnmower, or being touched by pets who may have run through the plants, are enough to cause a reaction and make it necessary to be able to correctly identify and eradicate this pest.

Washing in strong soap and water, or scrubbing off affected areas with rubbing alcohol may remove much of the sap from the hands, but care must be exercised to avoid spreading the affected areas. There is now a proprietary ointment on the market which may break down the active ingredient in poison ivy (known as ‘toxicodendrol’ or ‘urushinol’) if applied within the first hour before blistering and irritation begin.

Poison ivy may differ in appearance according to geographical region and sub-race. In the Hill Country and in West Texas, it may resemble a small shrub, but along riverbanks in Central and East Texas the plant may grow to become a large-trunked vine capable of climbing to the top of the average tree or telephone pole. The leaflets may be smooth or slightly hairy, with edges being lobed, toothed or smooth. Robert Vines, in his book Trees, Shrubs and Vines of the Southwest, describes a type with five leaflets instead of the usual three, which is found in Harris County. But in general it is easiest to remember the old bit of folk wisdom, “Leaflets three, let it be.”

Very young plants of poison ivy and box elder (Acer negundo) look very similar. To pull these up, use pliers. While holding the pliers, put a strong plastic bag such as a breadbag over the arm and hand, and uproot the plant. Then, peel off the bag off over your hand. The offending plant will be securely inside the sack, ready to throw away, and there will be no offending sap on the pliers.

Large vines on trees should be cut off both at ground level and again a few inches upwards, to ensure that a complete cut has been made. The base of the cut may be painted with Roundup, brush killer labelled for poison ivy, or another of the glypholysates. Watch for regrowth, and spray again with brush controller as new leaves appear. Take care that contact is not made with poison ivy roots while digging nearby. They are just as potent as the leaves and stems. It may take up to a year or more before the roots stop resprouting, sometime as much as 15 feet from the base of the vine.

The small fruits of poison ivy are known to provide food for at least 75 species of birds, especially wild turkey, bob-white quail, ruffled and sharp-tailed grouse, and ring-necked pheasants and mockingbirds.