Written by Brianna Wright
It’s that time of year again when horticulture inquiries from Marathon County residents have begun flooding into the UW-Madison Division of Extension’s office at 212 River Drive, Wausau.
Throughout the summer, local Master Gardener Volunteers meet every Wednesday from 10 a.m. to 2 p.m. to return calls and emails or meet with people regarding gardening techniques, soil testing, plant and insect identification, and plant pests and disease. Of the 355 questions answered via the Garden Line and Garden Clinics in 2018, one of the most common was related to wild parsnip, Pastinaca sativa — an herbaceous, invasive plant species often found along roadsides in Marathon County.
Why the concern over wild parsnip?
This species poses a health risk to anyone who encounters its sap.
If sap from the plant reaches a person’s skin, a rash and blisters may begin to form in the presence of sunlight — a reaction known as phytophotodermatitis.
When asked about wild parsnip, we stress the importance that you:
Wear gloves, long sleeves, and pants when handling this plant.
If you experience a negative reaction from wild parsnip, we encourage you to speak to a health professional for advice on proper care.
Wild parsnip begins life as a small, low-growing plant which will typically flower after its first year. Flowers on tall stems of this plant can grow up to 5 feet. Wild parsnip can be identified easily from many other species in the parsley family due to the small, yellow flowers (as opposed to white). You will notice flowers here in Marathon County during late spring to mid-summer.
If soil conditions allow, remove wild parsnip by pulling it out of the ground, bagging, and landfilling it. This will help prevent seed spread.
The timing of mowing wild parsnip is critical:
Mow after the flower emerges, but before the seeds develop, to prevent spread of this invasive species.
Other control options, including chemical, can be found in UW-Extension Learning Store publications, which can be accessed online for free at https://learningstore.uwex.edu/.
Answering your lawn, garden, and tree questions is merely one of the plethora of services that your Marathon County UW-Madison Extension provides.
If you would like help identifying any plant you think is wild parsnip, please contact our office at 715-261-1237.
For more information on wild parsnip, I invite you to download a fact sheet here, visit https://hort.extension.wisc.edu/articles/invasive-plants-wisconsin-wild-parsnip/, or watch the video below for helpful tips from UW Extension’s Dr. Mark Renz on identifying this invasive plant by its distinctive stem, leaves, and flowers.
Brianna Wright
Horticulture Educator | UW-Madison Extension
Brianna Wright is the Horticulture Educator with the Marathon County UW-Madison Division of Extension, where she has worked since 2018. She has a bachelor’s degree in Biology from UW-Stevens Point, and a master’s degree in Botany from the University of Wyoming. Brianna worked in the Department of Botany at the University of Wyoming for 11 years prior to moving back to Wausau in 2016. When she is not researching information on plants, fungi, and insects for work or pleasure, she can be found hiking the wilds of Marathon County with her husband and 3 beautiful children. Email Brianna Wright.
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