Watch out for Wild Parsnip!

The wild parsnip (Pastinaca sativa L) is a fairly common roadside plant in New England. A mature plant can grow about 45 inches tall. It’s considered the same species as cultivated parsnip and is also closely related to the wild carrot (Queen Anne’s lace). The parsnip has yellow flowers and Queen Anne’s lace has more feathery foliage and white flowers.
 
Some species in this plant family, including wild parsnip, can cause a painful, blistering rash if you cut or break the foliage, get the sap on your skin, and then get exposed to sunlight. The skin discoloration can last for months after the rash subsides. The term for such skin reactions is phytophotodermatitis. Many local physicians are unaware of this plant-caused skin reaction and attribute the problem to poison ivy.

The chemicals that cause this reaction are called furocoumarins, and occur in the leaves, stems and seeds. A related plant, giant hogweed, can cause even more severe burns.

The picture here is of a roadside plant in Lee taken August 1.The flowers have mostly gone by, 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 I experience the dermatitis myself to get first-hand photos of the injury. No thanks!

If you want to eliminate wild parsnip plants on your property, you have a couple of options. Just mowing or cutting them down won’t eliminate them, because they usually re-sprout from the roots. (Plus it might expose your skin to the sap.) Cutting off the taproot just below the soil line with a shovel is an easy method if you have only a few plants. Wear gloves, long pants and long sleeves to protect your skin if you choose this approach. Dispose of the plants in the trash to ensure the seeds won’t get carried off by small animals or the wind to sprout somewhere else.

If you have a lot of wild parsnip plants, chemical controls might be appropriate. Spraying the foliage with the herbicide glyphosate (Roundup, Kleenup and other brands) is one effective alternative. Be sure you follow label directions and precautions when using this (or any other pesticide).

But remember, chemicals may not be appropriate in some situations where special restrictions apply. Check state and local regulations before you spray near wetlands or surface water bodies and highway rights-of-way, for example. Also, if your home drinking water supply relies on a shallow (“dug”) well, you may want to avoid spraying any pesticide (or other chemical) within a 100-foot radius of the wellhead.

By Alan Eaton, UNH Cooperative Extension Entomologist and Pest Management Specialist