Wild Parsnip Advice

If you have it, you know it!

If you aren't sure, read carefully, because you want to be very careful around this plant!

Here is the management warning from the Illinois Nature Preserves Commission "Vegetation Management Guidelines" web page for this plant: "Warning-- Care should be taken to avoid skin contact with the toxic sap of the plant tissues by wearing gloves, sleeves, and long pants.Although eradication of this exotic is desirable from a human safety as well as ecological standpoint, in some situations the best control measure is to do nothing."

The plant is phototoxic - in other words, it gives off an oil that is activated by sunlight. And once activated, it can cause burn-like rashes.

I was at a conference recently, and asked several experienced land managers about parsnip - before giving me their management advice, each one would role up his or her shirt sleeve and point out scars earned during parsnip management work to be sure I knew how dangerous the plant was.

Despite the plant's toxicity, it can be controlled. NOTE: once the plant turns brown, it is ready to drop seed! So, while this advice is coming right at the end of parsnip season, it might help someone develop a plan of attack for next year.

Use the plant's life-history to your favor. It is a biennial, meaning that during its first year of growth it focuses on putting energy into its root system, and in the second year (or sometimes the third), it sends up a stem and blooms to set seed and create the next generation of plants.

With this in mind, it is ineffecive to herbicide the plant in year two, because the herbicide is designed to be delivered to the root when the plant feeds the root, and in year two, the plant is focused on producing seed, not feeding the root! That means the herbicide can't do its job. However, in the first year, herbicide works great because the plant is focused on putting food into the root, so if you are able to identify first year plants, spray away (using glyphosate, aka Roundup).

Here is a summary of the best advice I obtained about non-chemical control of the plant:

1. Wear long sleeves, long pants & gloves to be sure the plant does not touch your skin. After you finish any contact with the plant, thoroughly wash your clothes - including the gloves - take a shower just to be sure, and wash any tools that came in contact with the plant so you don't pick up the oil later. Another suggestion was to wear a miner's helmet with a light and cut the parsnip in the dark - the person who suggested this was quite serious!

2. If there are just a few plants, pull them out by the roots before they set seed. Destroy the plants by burning them. DO NOT leave the plants lying where you pull them.

3. If you have an infestation that is too large to hand pull, then try this approach: after the plants flower, but before they set seed, cut the seed heads off and gather the cut tops together to burn them. NOTE: the plants are likely to flower again and will set seed, BUT, the flowers will be smaller, there will be fewer seeds, and many of the seeds are likely to be sterile. In four or five years, this approach should result in a dramatically reduced number of plants. At that point, the remaining ones can be pulled.

4. If mowing the parsnip (because of size or resources), use a pull-behind tractor type mower, not a push mower, and definitely not a rotary cutter or weed whip! Those are much more likely to scatter the oil around where you or someone nearby can be harmed! Mowing should be timed carefully to occur when the plant has finished blooming but has not set seed. (Friday, August 1st would have been a good day - the plants I saw looked ready.) The area mowed should then be checked in a few weeks for resprouts, and if necessary mowed again.

5. One good piece of news is that sites with a well-established prairie planting are not likely to be invaded by parsnip, and, if an area is enhanced, the parsnip is likely to fade on its own over time.

6. Prescribed fire does not really help control the plant, BUT, it will make it easier to identify the first year plants in the spring since they will be some of the earliest plants to come up.

I'd like to thank my friend Vern LaGesse from Springfield for talking me through the ins and outs of parsnip management, and for reminding me to check the INPC vegetation management website because they have pulled a lot of good resources together to help individuals with managing weeds on their property.

This is a photo of first year growth

Do you have an experience with parsnip control to share? I'd love to hear it!!

Some facts FYI:
Life history: Wild parsnip typically lives for two years. The first year, as a spindly rosette of leaves, it keeps fairly low to the ground while the plant's carrot-like taproot develops. It may live two or more years this way until conditions are right for flowering. The second year, a hollow, grooved flower stalk rises 2-5 feet high, first holding clusters of yellow flowers and later dozens of flat, oval seeds.

Leaves: Pinnately compound, with a main stem and 5 to 15 leaflets.

Flowers: Yellow, in flat-topped umbrella-like clusters at the top of the plant.

Season: Wild parsnip rosettes are among the first plants to become green in spring, and its flowers turn a prominent yellow in midsummer. After flowering and going to seed, plants die and turn brown in fall, but first year rosettes remain green until frost.

Habitat: Roadsides, abandoned fields, unmowed pastures, edges of woods, prairie restorations.