by Ken Schroeder, Portage County UW-Extension Agriculture Agent
Wild Parsnip, Pastinaca sativa, is an invasive member of the carrot family that continues to spread into unmanaged areas throughout Wisconsin. It likes to grow in sunny, grassy areas along roadsides, railroads, and field borders but is not limited to these conditions. Primary means of spread is by seed that can be moved long distances while mowing roadsides after the plant has set seed.
What’s the concern? The biggest concern isn’t the fact that it is invasive and rapidly spreading but that it will cause burns and blistering of the skin if you come in contact with plant sap in the presence of sunlight. This is known as phytophotodermatitis. Blisters and rashes appear 24 to 48 hours after exposure. Blisters do not spread like poison ivy but are uncomfortable and may leave scars lasting for several months to two years.
How do we identify wild parsnip? The plant is a monocarpic (the plant dies after blooming) perennial and has two growth stages. The first year it produces a non-flowering leafy rosette of pinnately compound leaves with 5 to 15 leaflets. It looks a lot like celery at this stage. In the second to third year, it produces a flowering stem four to five feet tall. Stems are grooved, hollow, and have alternately arranged compound leaves with 2 – 5 pairs of opposite, sharply toothed leaflets and petioles that wrap around the stems. Flowers are flat-topped clusters (umbels) of yellow flowers 2 – 6” wide blooming in late spring to mid-summer in Wisconsin. Seed begins to form mid to late July changing from yellow-green to tan as they mature. Along with the seeds maturing the stems and leaves begin to senesce, turning tan to brown in color.
How do we manage wild parsnip? Early detection when populations are small allow for pulling or digging. Be sure to wear gloves, long sleeves, long pants, and safety glasses or face shields to avoid skin contact with the sap. One can simply cut the taproot with a shovel or spade 1 – 2” below the soil surface. With larger populations mowing is an option if done after emergence of flower heads, but before seeds enlarge. Additionally, several chemical options exist. Be sure to read and follow label directions when using chemicals. For more detailed management options see the UW-Extension wild parsnip management publication A3924-15 at the Learning Store website https://learningstore.uwex.edu/ .
What can I do as a Master Gardener to help?
- Know how to identify wild parsnip and report locations at the Wisconsin First Detectors Network website http://fyi.uwex.edu/wifdn/get-involved/report-invasive-species/. Several options are listed including a downloadable smartphone app.
- Educate others about the existence and danger of wild parsnip.
- Carry a sharp shovel or spade with you and when you see only one or a few plants consider cutting off the stems below the soil surface. As long as they haven’t gone to seed the plants can then be left to die. Check back the next year to see if additional plants emerge and cut those too. CAUTION do not do this on private property without getting permission from the property owner.
Additional invasive species information
- The University of Wisconsin Weed Science website http://fyi.uwex.edu/weedsci/ is a great resource for weed id and management info and has several short YouTube videos to help with identification.
The Wisconsin DNR invasive species website http://dnr.wi.gov/topic/Invasives/ has a wealth of information on not only terrestrial invasive species but aquatic and wetland invasives as well.