Be Careful Around Wild Parsnip

Wild parsnip is a fairly common roadside plant in New England. The scientific name is Pastinaca sativa L.  A mature plant can reach about 45" tall. Yes, it is considered the same species as cultivated parsnip and is also closely related to wild carrot (“Queen Anne’s Lace”). The parsnip has yellow flowers and Queen Anne’s Lace has white flowers.   

What’s the problem?  If you cut or break the foliage, and get the sap on your skin, then get exposed to sunlight, you can get a serious rash and blistering.  Many local physicians are unaware of this plant causing such a reaction, and attribute the problem to poison ivy.  If you like long names, the term for the reaction is phytophotodermatitis.  The skin discoloration can last for months after exposure.  The chemicals that cause this reaction are called furocoumarins, and occur in the leaves, stems and seeds.  A related plant, giant hogweed, can cause severe burns.

The picture here is of a roadside plant in Lee, NH that I took August 1st.  The flowers have mostly gone by on this one, but the seeds are highly visible.  Apparently this plant is more common in northern parts of New Hampshire than in the seacoast, where I live.  A colleague suggested that I experience the dermatitis myself, and get first-hand photos of the injury.  No, thanks.

If you want to eliminate this plant, there are several options.  Just mowing or cutting them down won’t eliminate it because it usually re-sprouts from the roots. (Plus it might expose your skin to the sap.) Cutting off the tap root just below the soil line with a shovel is an easy method if you have a few plants.  If you have a lot of plants, chemical controls might be appropriate.  Spraying the foliage with glyphosate (Roundup, Kleenup and other brands) is one effective alternative.  Be sure you follow directions and precautions when using this (or any other pesticide).  But remember using chemicals may not be appropriate in some situations.  Special rules and laws apply to situations near water or highway right-of-way, for example. 

Alan Eaton,   UNH Cooperative Extension Specialist, Pest Management