Controlling the Invasive Wild Parsnip
Driving along the highways from mid-June to August and you can’t help but notice the tall plants that often extend above the grasses and have a flat yellowish/greenish head on them.
These are wild parsnip, an invasive plant that tends to crowd out native plants. Landowners are seeing the plants along the edges of their woodlands and in their prairies.
The wild parsnip (or more formally Pastinaca sativa) has a two-year cycle. The first year it comes up as a rosette with large grooved leaves. It is only 5 or 7 inches tall. The second year it sends up a tall stalk, some 2 to 5 feet tall, and the flower can be seen above the grasses.
One way to help control the plant is to mow the plants when the flowering head is present, but before seed is produced. The timing is important, because if the mowing is delayed until August when the head turns a bronze color and seed is mature, you (and many county highway departments) are just spreading seed around to bring up more plants next year.
Another excellent way to control the plant is to use a spade or shovel or tool known as the “Parsnip Predator” to cut the long carrot-like taproot below the soil. This fools the plant into thinking that it has completed its process and it dies. You can discard the head (or put the top in a plastic bag to be discarded in the trash if the seed head is mature).
The thing to be aware of with wild parsnip is that it produces a chemical that, if it gets on your bare skin, especially when the sun is out, will produce a rash and blisters on your skin. (The reaction is called phytophotodermatitis). These can be very painful, and a reason to wear gloves, long sleeves and long pants when working with the plants.
Landowners should walk their land and get to know the various plants in their woodlands and grasslands, and take an active part in trying to eliminate the invasive plants that are quickly creeping onto the landscape.