Beware of plants that have leaves of three. WARREN WILLIAMS / Courtesy
Q: Poison ivy suddenly appeared in my garden. Where did it come from and how do I get rid of it? Anita H., Tulsa.
A: Poison ivy can definitely take the fun out of gardening. It is common in Oklahoma and can produce a severe rash upon casual contact. It is estimated that more than three-quarters of the population is allergic to poison ivy.
Poison ivy is distinctive for having clusters of three leaflets per stem. The leaflets have sharp tips and their edges may be smooth, toothed or lobed. It may be a low-growing vine, a shrub or a large tree-climbing vine. Vines on trees may be several inches thick, covered with hairy rootlets and may climb many feet up the trunk. These are the pretty red vines on tree trunks one sees along the highway in early fall.
A mnemonic rhyme to help remember its characteristics is:
Leaves of three, let it be;
berries white, danger in sight.
Leaves of three, let it be;
hairy vine, no friend of mine.
Although poisonous to humans, poison ivy's grayish-white berries are eaten by birds with no harmful effects. Bird droppings could be the source of your poison ivy plants.
The poison is an oil - urushiol - and is found in all parts of the plant - leaves, stems, berries and roots. It is easily absorbed by casual contact during all seasons, including winter. On clothing, it may persist for months if not laundered. It also may be spread by pet fur and in droplets in smoke, if the plant is burned.
The FDA recommends washing exposed areas of skin in cool water as soon as possible after exposure. Once the toxin is absorbed by the skin, it cannot be washed off. A rash develops hours to days after contact. After developing, the skin rash will not spread the toxin to other people.
Poison ivy may be eliminated by digging up and removing plants or with herbicides. When removing, always use protective clothing, gloves and eye protection. All plant parts should be bagged and discarded.
Herbicides are effective but may need more than one application. Products containing triclopyr, which is found in brands such as Ortho Brush-B-Gon Poison Ivy, are the best choices. Glyphosate, found in Roundup and others, is also useful. Poison ivy should be on the label and labels should be followed carefully because each herbicide has different characteristics.
Glyphosate concentrate can be used to paint the stumps of vines immediately after they have been cut; this is effective in killing any vine to the roots. It is especially effective on the large poison ivy vines attached to tree trunks.
If you have a garden-related question you would like the Master Gardeners to answer in a column, call 918-746-3701.
Gardening tips
It is time to divide and replant spring-blooming perennials like iris, peonies and daylilies if needed.
Areas in the lawn under tree limbs awaiting pickup by the city will be brown after they are removed. Fescue lawns will need reseeding. Bermuda grass likely will recover but may take until next year's growing season to do so.
If you plan to reseed fescue lawns, begin scouting for good seed, there is no "best" variety. Purchase a fescue blend of three or more varieties, with or without Kentucky bluegrass. Read the label on the seed bag. A good blend will have 0.01 percent or less of undesirable "other crop" seeds.
Original Print Headline: Watch out for poison ivy
Home & Garden
All Helenium species are native to North America and were introduced to Europe in 1729 and, by the 1940s, many cultivars were available from German and English breeders.
Q:I have enjoyed the blackberries available at the local farmers markets. Are blackberries practical for the home gardener? M.D., Tulsa
