It’s a common dilemma– you want to get rid of rash causing weeds, but you don’t want to get a rash in the process.
Poison ivy, poison oak, poison sumac, wild parsnip, cow parsnip, giant hogweed and other weeds can all cause significant irritation. Any one of them can make the next few weeks of your summer itchy and miserable. Over the past few years, poison parsnip, or wild parsnip, has become a more and more widespread problem across the US.
How to Identify Wild Parsnip
Wild parsnip often grows along roadsides and if nobody mows it, by midsummer it will be several feet high and covered with masses of small yellow flowers in an umbrella shape (like carrots or dill). The leaves have a sawtooth edge. During the first year of growth, you may see only small rosettes of these leaves.
At some point, usually during the second year, the plant will send up a tall stem and an attractive yellow umbrella shaped cluster of flowers. While it is in bloom it is easy to identify and you still have time to eliminate it before it forms seed heads and plants a bumper crop for next year!
Sap from the stem, leaves or flowers of the wild parsnip can react with sunlight to cause burns on your skin. The reaction is called “phytophotodermatitis.” The rash can look a bit like a sunburn. It may include blisters and generally appears within a couple days of contact with the plant. Discoloration can last for several months.
How to Get Rid of Wild Parsnip
Use caution when working around wild parsnip and other rash-causing plants. No matter what your weed problem, follow these 6 easy steps to get rid of the weeds without using harsh chemicals and dramatically cut your chances of getting a rash from these weeds.
1- Cover Up— Wear protective clothing. Long pants, shoes and socks, long sleeves and gloves are all musts. Protective eyeware is also a good idea. You don’t want the saps or oils from these plants to get on your skin or in your eyes.
2- Keep Your Distance— Work at arm’s length whenever possible. Rather than getting your face down in the weeds, use long handle tools or mowers to keep yourself at a distance from the plants and to help you avoid the saps and oils that cause the problems. Individual plants can be cut off below ground level with a sharp spade or a dandelion fork. But larger patches of the weed may have to be mowed or eliminated with a brush cutter.
3- Stay Cool— Work during the cooler part of the day and on cloudy days, if possible. Sunlight, sweat and heat can all increase the rash causing potential of these plants.
4- Use Herbicides Wisely— If you don’t want to use a systemic herbicide, then your alternative is a burn down herbicide, such as Phydura. Use this to attack plants you can’t uproot or mow. Because this type of herbicide attacks the foliage and not the root, it will take more than one application to kill the plant. However, even if you don’t succeed in killing the root, you will have slowed the spread of the plant. If you eliminate the leaves, stems and flowers late enough in the summer, plants like poison parsnip won’t have time to make seeds before winter hits. If you miss your window and seeds do form, apply a pre-emergent herbicide, such as Dynaweed in fall or spring, to help keep those seeds from sprouting. And if you can learn to identify the first sproutings of this noxious weed, that is the ideal time to spray them.
5- Be Careful With the Debris–Do not burn or compost wild parsnip plants that have been cut down or dug up. If possible, leave the stems to dry out completely at the site. Carefully dispose of plant material in black plastic bags and leave in direct sun for a week or more. Contact your municipality to determine if the bagged plants can be sent to your local landfill site or not.
6- Cut the Grease— Wash up immediately after all your hard work. Include your tools in this clean up, and remember to launder your clothing separately. Most important, of course, is to remove any oils and saps from your skin. Use a grease-cutting detergent. Consider using special soaps that are designed to remove the rash causing saps and oils from your skin and clothing.
Controlling perennial weeds takes consistent effort. But with time and attention you can bring poison parsnip under control and avoid suffering its itchy rash.
For more about identifying rash causing plants, click here for an illustrated guide put out by the University of Illinois.