Banner year for pesky wild parsnip
One has to wonder what prompted European settlers to decide wild parsnip was worth bringing here to cultivate.
Sure, as the name implies, it does have an edible root with a flavor described as both sweet and spicy if harvested at the right time. Apparently that’s after the first year; it doesn’t put up its tall stems and bright yellow, flat-topped flowers until its second year.
But the plant itself is armed above ground with a bitter sap that not only is toxic if ingested, it will react with sunlight to produce burns and blisters on skin.
This does not sound like a good candidate for the garden.
Perhaps because it would be pulled up before the plant could go to seed that second season, it was assumed it would be controlled. It wasn’t.
Instead, wild parsnip has spread extensively and now can be found across southern Canada and in the United States from east to west coast. In fact, only five states — Hawaii, Mississippi, Alabama, Georgia, and Florida — can claim to be wild parsnip-free.
In our area, wild parsnip definitely has been in the region for some time — when making the drive to and from La Crosse, Wis., I’d see whole fields of it in Florence County.
But in the roughly 5 1/2 years I’ve lived here, I’ve not seen it as widespread as it has been this summer. Felch has large yellow patches between buildings and homes. Almost every mile of M-95 from the junction with U.S. 2 north to Randville — and probably beyond — seems to have a clump of it. Make the turn east on M-69 and the stretch to the North Branch of the Sturgeon River is virtually lined on both sides of the highway with wild parsnip, though weed cutting by the county has created some gaps.
In past summers, the river appeared to have been a barrier to it going farther down M-69. Not this year. And, as mentioned, it is well-established in Felch far to the east.
And for the first time, wild parsnip has cropped up at Six Mile Lake. While only a handful of plants, it’s cause for concern, being along a road where people walk with pets and children play.
I can imagine a kid picking the “pretty” flowers, which look like a yellow version of Queen Anne’s lace, to bring home.
If exposed to the sap, experts recommend washing the site thoroughly with soap and water, then keeping it covered for at least 48 hours to avoid a reaction. If a reaction does occur, keep the affected skin out of the sun to prevent further damage and see a physician.
Wild parsnip is not just a hazard for humans. Livestock that tries to feed on it can be harmed as well, which poses a problem for agriculture if it becomes established in a pasture or forage crops.
So how does wild parsnip spread so readily? Like several other invasive plant species that have taken hold here, it probably hitches a ride as a seed to passing people, animals or vehicles, such as an ATV traveling through a roadside ditch or trail where wild parsnip has grown.
After it blooms in its second year, wild parsnip sets seeds and dies. Those seeds can remain viable in the soil for years, according to the Minnesota Department of Agriculture.
So it helps to kill the plant before it goes to seed, especially if it’s not an extensive infestation. To deal with wild parsnip, the MDA advises:
— Given the effect the sap can have on human skin, hand pulling generally is not recommended. But small numbers of plants can be removed by hand if using sturdy gloves and clothing as protection. First-year wild parsnip rosettes and recently bolted — rapidly growing — stems that have not set seeds can also be killed by using a sharp spade or shovel to sever the tap root 1 to 2 inches below the soil surface. Sites should be re-checked periodically to remove re-sprouts and recently germinated seedlings and rosettes.
— Mowing or cutting larger stands before flowering in June will kill a majority of mature plants and significantly reduce seed production. Repeated mowing throughout the season and for several subsequent years is required to prevent re-sprouting and to cut newly bolted plants. After mowing an infestation, wash equipment to prevent moving seed into new areas.
— Use a selective broadleaf herbicide in the early spring or late fall to target rosettes and newly bolted plants prior to flowering. Several years of treatment may be required to control the overall population until the seedbank is exhausted or other vegetation begins to compete with the remaining plants. The MDA recommends checking with a local Extension agent, co-op, or certified landscape care expert when considering chemical treatments.