Know thine enemy: Poison Parsnip
by Peg Rosenau
I intentionally awoke quite early last Saturday. I knew it was going to be an incredible day – sunny, dry, and warm. It immediately became apparent that everyone else had the same idea of how they would spend the day – on outdoor garden and lawn projects. Everywhere people were weed-wacking, chopping, mowing, and digging and the collective sound of neighborhood landscaping tools made me wonder if a Nascar race track had been built nearby. I was eager to get out there myself- but not before donning a pair of gloves and a long-sleeved shirt. One has to be prepared in case of a horticultural run-in with a nasty invasive species that is lurking in our region: Poison Parsnip.
Poison Parsnip (or wild parsnip as it is commonly called) has been spreading rapidly in Vermont over the past few decades especially along roadsides, fields, and yard edges. In Shelburne, lots of it can be seen along the Ti-Haul Path, LaPlatte Nature Park, and the cross county paths behind the Shelburne Museum. Native to Europe, the plant resembles a giant Queen Anne’s Lace, with a yellow – rather than white – cluster of flowers. Unlike Poison Ivy, the leaves of Poison Parsnip are not harmful when one brushes up against them and the plant is even considered beneficial by some as the long tap root can be eaten (though most children will vigorously dispute the “edible” designation). However, an unfortunate outcome may await those who unwittingly pull or mow the plant on a sunny day: phytophotodermatitis. It’s as unpleasant as it sounds. A chemical reaction of the skin caused by contact with the plant’s sap and subsequent exposure to sunlight. Burns can vary from a mild rash to intensely painful blister-like sores that can require hospitalization. Even after healing, affected areas often remain scarred and discolored.
The best defense against Poison Parsnip is learning to recognize it in its various stages of growth and employ safe methods when handling or removing it. A biennial, the plant takes two years to mature. The first year’s growth is only a low-growing rosette of serrated leaves that are similar to those of celery. Mature plants send up a large flower stem that can be over six feet tall and is topped with a large flower that is actually a cluster of smaller flowers. The yellow flowers turn brown as they go to seed and the seeds easily find their way to new locations on muddy shoes, bike and car tires, and in hay bales cut for animal feed. Each flower head can produce hundreds of seeds so any efforts at eradication must involve seed control. The flowers should be cut well before seeds are produced, and disposed of in a place that they will thoroughly compost. This method will require several weeks of vigilance as the plants bloom over a rather long duration. The plants can be dug out at the root, though the root may regenerate if it is not completely removed. It is best to use this method earlier in the season when the roots are smaller and when the ground is loosened. Always wear long clothing that covers as much skin surface as possible, and try to work on a day that is rainy or overcast. If exposure is suspected, wash skin thoroughly with soap and water and stay out of the sun for awhile. It is a bit of work to eradicate parsnip, but the efforts will pay off – especially if there are only a few plants in a particular location. It can be eradicated in an area if tackled before the population get out of control.
Removal may not be a project that many are willing to undertake, but avoidance of sap exposure should be of interest to all. It is worth taking some time to search for pictures on the web to familiarize oneself with the weed in its different stages, and yes, peruse some of the gruesome rash pictures for extra incentive. And even though most kids already naturally avoid the cooked roots of the parsnip, make sure they also know not to cut and handle the flowers of the plant itself.