Wild parsnip a burden

By Kate Klimesh,

Wild Parsnip can be a hazard for outdoor tourism if the delicate yellow flowers make direct contact with skin. While pretty from a distance, the flower exudes a substance which causes a reaction with sunlight to often cause painful blisters, which can lead to scarring and discolored skin for what can be more than six months.

By Kate Klimesh

At the July 31 Winneshiek County Board of Supervisors Meeting, resident Kandi Sheffield presented information to the Board of Supervisors regarding county-owned public access property, part of the Emergency Watershed Protection (EWP) program, that was not being maintained. Sheffield relayed that approximately 80 percent of the almost 34-acre parcel directly across from her home on Clay Hill Road in Decorah was covered in wild parsnip, a toxic plant that can cause injury with direct contact. Sheffield requested the supervisors consider a maintenance plan to eradicate or minimize the wild parsnip to ensure the safety of the local and visiting people attempting to utilize the canoe access or simply access the public land on that property.

“The native plantings are getting choked out by the wild parsnip. I see people going through the property, I can only imagine the pain from wild parsnip exposure they may not realize until too late,” Sheffield reported. “My daughter went in to help a neighbor and was hurt badly by the oils, with scarring from blisters.”

Sheffield relayed photos of the quarter-sized blisters and subsequent scarring from the wild parsnip exposure her daughter experienced. “The wild parsnip oil’s purpose is to cause cell death through direct toxicity from anything above ground – flowers, leaves and stems.” She also noted wild parsnip was reported along local bike trails, leading to injury of trail-riders. “Wild parsnip burns are not a good souvenir after coming to the county.”

Sheffield noted eroding banks at the canoe access creating a sheer drop-off to the river, and steep banks littered with wild parsnip from the road to the river. Sheffield and Emily Rocksvold also shared several grant programs through NCRS, Iowa DNR and Fish and Wildlife available to fund EWP areas and public access property rehabilitation and other suggestions for maintenance. “We’ve presented some great options to maintain this property at no cost to the county and hope you will consider this as a priority for the safety of the people in the county,” Sheffield concluded.

Toxicity to cell systems

Wild parsnip toxicity to skin comes from a substance found in flowers, leaves and stems called “psoralen,” which causes painful blisters if in contact with skin, and the skin is then exposed to sunlight. Exposure to wild parsnip and sunlight can cause a severe burn within 24-48 hours, so those exposed during an outdoors adventure may not realize it until much later. Reactions can range from a mild rash to blisters, skin discoloration and even burning pain. Blisters can cause scarring from the reaction that can last many months.

So why isn’t wild parsnip considered a noxious weed? It is considered a naturalized plant, found in every county in Iowa as early as 1926. County Roadside Management programs to establish native habitat less prone to weedy species, but primarily focuses on Iowa’s listed noxious weeds, which does not include wild parsnip. Roadside programs also have to follow state regulations, which state that roadsides may not be mowed until July 15 to protect nesting bird habitats.  

Wild parsnip flowers mainly from May-July, produce a large amount of seed and spreads rapidly. Mowing after July 15 on roadsides may not be as effective at controlling the spread of the plant, as mowing prior to flowering, at least by June, is recommended to kill a majority of mature plants and reduce seed production. Monitoring for several weeks following a mow can help catch any so-called late bloomers, with another mowing pass to help eliminate seed production from late bloomers.

Efforts to prevent the spread of wild parsnip can be labor-intensive when trying to dig out the root crown of each plant; some herbicides are effective in control of the weed and are best applied early spring or late fall. Several years of monitoring an affected area is required to catch the plant early and prevent additional seed production. Seeds can remain viable for up to four years once in the soil.

Prevent injury

Learn how to identify wild parsnip in outdoor spaces and protect yourself from those you may not see, especially when visiting the area’s rivers, trails and parks. When working in or around wild parsnip, always wear proper clothing and gloves that protect the skin from contact with the toxic plant sap. As the plant can grow four to six feet tall, covering your feet, ankles, legs, torso, arms and hands when walking through tall grass at a public area can help prevent direct skin contact.  

Those who suspect they may have psoralen on their clothing or gloves is encouraged to treat their clothing with care, as the substance may yet transfer to skin. Even washing off immediately after exposure may not prevent injury. Keep in mind pets may also be affected by the psoralen.

For more information, visit your state’s university extension website or call for further details.

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