Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
July, 2009
Regional Report

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You can bet that I was very careful taking this photo of wild parsnip, now that I know that its sap can cause painful, blistering burns.

Stalking the Wild... Parsnip?

Because I'm growing flowers for a friend's wedding in September, I'm on the lookout for wildflowers along the side of the road and in fields... Just in case my zinnias succumb to powdery mildew or we get another hailstorm that flattens the cosmos. I know I'll be turning to wild Queen Anne's lace as a filler, but I've also been eying a similar umbel-shaped flower, this one a nice chartreuse.

Then, just in time to keep me from experimenting with this flower in bouquets, a headline story shows up in our local newspaper. It turns out this beauty is wild parsnip (Pastinaca sativa), a relative of Queen Anne's lace, as well as cultivated parsnips and carrots, and, notably, poison hemlock.

Ann Pearce, a Burlington-based professional gardener and Vermont Master Gardener, recently issued an e-mail alert to her colleagues:

"Beware the wild parsnip! Now in full bloom along roadsides, in fields and sunny disturbed areas all over Vermont, this tall yellow-flowering plant that looks like a yellow Queen Anne's Lace can pack blisters or burns worse than poison ivy if you get the juice from the plant on your skin and your skin is then exposed to the sun. Phytophotodermatitis it's called. The blister/burn scars can remain for a long time on people who are more allergic." [Note that by the time this is published, the plant will be past peak bloom and beginning to set seed.]

Thank you, Ann and the Burlington Free Press, for saving me a painful lesson. And had I waited until the day of the wedding and used the flowers in bouquets and arrangements, well, what a horror show that might have been had the bride and guests been exposed to the sap then enjoyed some sunshine at the outdoor festivities.

Hailing from Europe and Asia, wild parsnip has naturalized in many parts of the country. Unlike poison ivy, you don't need to be allergic to it -- anyone and everyone will be affected. The burns are similar to severe, blistering sunburn.

Wild parsnip spends its first year or two as low-growing rosette of leaves. When conditions are favorable, it sends up a flowering stalk, produces seeds, and the plant dies. Limited infestations can be kept in check if you dig up first-year plants as soon as you see them, so learning to identify the rosettes is key. Cutting second-year plants a few inches below the soil line minimizes resprouting. The goal is to prevent them from flowering and setting seed. If the plant is already blooming, you can cut it down and dispose of the entire plant, before the seeds have a chance to mature. Of course you must wear protective clothing to do this.

Since the burns result from a reaction to the combination of sap and sunlight, one of the worst things you can do is use a string-trimmer to mow down the weed. Small, shattered, sap-oozing bits fly about, landing on bare skin. Unless you do your trimming at night, you're asking for trouble. Some experts recommend spot-treating the plant with an herbicide. There are some new organic herbicides on the market if, like me, you try to avoid synthetic ones.

It just goes to show you, you can never know everything about plants and gardening. There's always something new -- and even if the news is unpleasant, at least it keeps you on our toes.

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