Poison Parsnip: How to Tackle This Relentless Beast of a Plant

by Laurie Danforth

Right now there is an invasive biennial attacking our roadsides and it’s called POISON PARSNIP (Pastinaca sativa). Yes, it’s a parsnip whose root is edible and its sap dangerous. Flowers are flat topped umbels 3-6 inches wide with numerous yellow flowers.

Think of the white flowers of Queen Anne’s lace and then imagine them yellow. You can see it along the roadside on Rte 11 to Springfield or out toward Londonderry. Once populations build they can spread rapidly and overtake native plants that are helpful to our local wildlife. 

Wear protective clothing when working around this plant as the sap can cause severe burning when your skin is exposed to sunlight. Better yet work on a cloudy day and wear long sleeves and pants. Even a light-colored short-haired dog can suffer from contact with the poisonous sap. It’s a good idea to wash your clothing after working amidst the plants. 

NOW IS THE TIME! So how do you fight back to eradicate this Parsnip invasion?

Number one is that you must deal with the plants prior to their setting seed.  Seeds are their mode of taking over. If you have a small number of plants or if plants are mixed in with other plants you won’t want to mow. In this case pulling out or cutting below the surface with a spade is a good option before the plants go to seed. If you have more Poison Parsnip than you can deal with by hand, then mowing is a must. In this case you have to be sure to clean your mowing equipment after working in the area. You MUST bag up your plants and do NOT put them in the compost pile! 

I played vigilante and recently cut off all the flowers on some plants along Grafton Road. I realized that even though the flowers were cut off and laying in my garage, the seeds were STILL developing.  That should give you a clue as to how invasive and aggressive Poison Parsnip is.  It has a lot of weapons in its arsenal.  Be sure to recheck for any late flowering plants in the area under attack and next year keep an eye out for new plants. Within  3-4 years, with careful surveillance, you will be able to eradicate this toxic invader and make way for our local native plants. That might sound like a long time, but, believe me, it’s worth the effort.

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