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Know what you grow — especially if it’s poison ivy

Oh no, not again. Forearms tingling with a burning itch, reddened bumps and welts pushing up through the skin and no, no, no, must resist the delicious urge to scratch the rash.

As predictably as the home gardener greets the warm weather by happily planting colorful annuals in pots and window boxes and preparing the garden beds for perennials by pulling out underbrush and weeds, so does poison ivy quietly infiltrate the landscape and leave its touch on the unwary.

Self-described plant nerd Pamela J. Bennett, director of the state’s Master Gardener volunteer program and an associate professor and horticulture educator for Ohio State University Extension in Clark County, shares tips for what to do about poison ivy and other nuisance plants that may show up in your yard.

First off, Bennett said, people should know what’s growing on their land.

“A gardener should identify the plants they have in their garden and then look them up or do a computer search for poisonous landscape plants,” she said.

Find a plant that raises questions? Take a picture of it to your local Extension office, Bennett said, or to a garden center.

Or submit your plant picture and questions online through the Ask a Master Gardener feature available on all county Extension web pages, she said.

Collage of Poison Ivy, plants photos, © 2019 The Ohio State University

Poison ivy

Poison ivy is the most common nuisance plant, and its urushiol oil causes the most common rash. “Birds drop poison ivy seeds everywhere,” Bennett noted.

Avoid exposure by wearing gloves, a cap, long sleeves and pants, and closed-toe shoes. If you’re exposed, apply rubbing alcohol to your skin and then take a warm, soapy shower, and wash your gardening clothes separately in hot water.

Never burn poison ivy. Carefully cut it back in August, let new growth sprout and then spray it with an herbicide specifically labeled for poison ivy in September or early October, before the first frost, Bennett said.

Collage of Hog Weed, plants photos, © 2019 The Ohio State University

Giant hogweed

Giant hogweed, a noxious weed that crowds out native plants, has started showing up in northeastern Ohio, Bennett said. Its sap causes skin sensitivity to the sun, swelling and blistering and possible permanent scarring. Eradicate it as soon as you identify it.

Collage of Hemlock, plants photos, © 2019 The Ohio State University

Poison hemlock

Poison hemlock is another invasive weed in Ohio and also among the most lethal plants in North America. Its toxins must be ingested or taken in through the eyes, nose or a skin cut to cause poisoning. OSU Extension recommends controlling it with herbicides, Bennett said.

Wild Parsnip, plants photos, © 2019 The Ohio State University

Wild parsnip

Wild parsnip is an invasive plant in Ohio that commonly grows in and around poison hemlock. Its sap on skin interacts with sunshine to produce severe blistering and skin discoloration. Extension recommends herbicides to control its growth.

Collage of Tree of Life, plants photos, © 2019 The Ohio State University

Tree of heaven

Tree of heaven is an invasive deciduous tree. It gives off a foul odor often said to smell like rotting peanuts or cat urine. Small plants can be pulled, dug or mowed, but eliminating larger ones requires an herbicide.