Identifying Wild Parsnip

Identifying Wild Parsnip

Part of Ep. 1702 Think Green

UW-Extension Horticulture Educator Lisa Johnson describes what dangers Wild Parsnip presents to human and native plants and how to combat it.

Premiere date: Apr 29, 2009

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
We are in western Dane County near Blue Mounds to look at well, not your garden variety type of weed.  This is a very special weed.  I'm with Dane County UW-Extension Horticulture Educator, Lisa Johnson.  Lisa, what makes this a special weed?

Lisa:
Well, Shelley, this is actually an invasive species.  It's classified as an invasive species.

Shelley:
So it is special!

Lisa:
Oh, yeah, you could say that.  This plant is in the carrot family.  And it's called wild parsnip.

Shelley:
That's this field of what we're looking at here.

Lisa:
Right, exactly.  It has several things that make it an invasive species.  The first one is that it invades our natural areas, particularly our prairies.  Because it's a sun plant.

Shelley:
So we're losing prairie plants as these things spread.

Lisa:
Right, it out competes them.

Shelley:
Okay.

Lisa:
Another thing is that because it's a non-native plant, it doesn't have any insects that feed on it here.  It doesn't have any diseases to help keep it in check.  It doesn't have any other kinds of predators that feed on it.

Shelley:
Nothing to stop it.

Lisa:
No, party on!  So this plant is very happy here, and it's spreading quite nicely.

Shelley:
Let's talk about these so people know what it looks like.

Lisa:
It starts out as a basal rosette of leaves that are about a foot tall.  And then, eventually, as it gets enough energy to produce a flower stalk, one or two years, it will then produce this very tall flower stalk.

Shelley:
Which is quite pretty.

Lisa:
Yeah, it is.  It looks somewhat like Queen Anne's Lace, in that it's a flat umbrel.

Shelley:
Only it's more yellow.

Lisa:
Right, a chartreuse color.  It first produces that large umbrel and then it produces the side flowers.  It usually starts to bloom beginning to middle of June.  And it will start to go into seed around the end of June, beginning of July.

Shelley:
And how does it spread, by plant of by seed?

Lisa:
Mostly by seed.  Each plant can produce 300 or so seeds.

Shelley:
Wow, and you said it's a sun plant.  So we're going to see it in prairie areas.  Where else? 

Lisa:
We see it a lot along the roadsides.

Shelley:
Disturbed areas.

Lisa:
Exactly, but also in areas like dog parks.  We're seeing it a lot in new developments.  So people are coming into contact and finding it a lot more now than they used to.

Shelley:
And so, the main reason we're concerned about it is because it's destroying habitat for prairie plants?

Lisa:
Well, there's that.  But there's another reason as well.  It's a health risk for people.

Shelley:
Oh, really?

Lisa:
Yeah, this plant contains a chemical that when you get the sap of the plant on your skin, and you expose it to sunlight, it causes a chemical reaction that causes a chemical burn.  And this is called, it's a long word, phytophotodermatitis.

Shelley:
Ooh, it sounds serious, too.

Lisa:
It sounds serious, and it is.  It will burn, like a sunburn.  Some people have a lot of itching along with it.

Shelley:
A real burn.

Lisa:
Right, a real burn.  You get big blisters.  And the blisters can leaves scars that can last for a number of years.  Big brown scars.

Shelley:
And that's from the sap.  You touched the plant.

Lisa:
Yeah, I touched the plant, that's okay.  It's just if you break it and you get the juice on your skin.

Shelley:
So, cutting that and putting it in a vase is not really a good idea.

Lisa:
I wouldn't!

Shelley:
And it's so easy to weed whack, or something like that.

Lisa:
Some of the worst blister cases that I have seen have been from using a weed wacker, where you get the juice and pieces of the plant flying all over the place.

Shelley:
That might be tough for kids rolling around in it, or something like that.

Lisa:
Right.

Shelley:
Then what do we do about it?

Lisa:
Well, there are a couple different methods you can use for controlling it.  If you have just a small infestation, you may want to try mowing.  I'd use a power mower.  And you should do it about now, when the plant is in it's full flower stage.  If you do it too early, it'll just bloom again and produce more seeds.  But you probably will have to mow twice, at least, during the season to get rid of it. 

Shelley:
So early ID is crucial, so you can plan ahead.  But if it causes this burn, would it be wise to mow when the sun's gone down?

Lisa:
That's a great idea.  You should also protect yourself by wearing long pants, long sleeves, protective eyewear, gloves.

Shelley:
It's a serious issue.

Lisa:
Yeah, it is.  You can also, if you just have a few of them, you may want to try and dig it out using a sharp shovel.  And if you get a couple of inches below the crown of the plant, that should take care of it.  Again, after sunset.

Shelley:
Really?  So on those long summer days, maybe not in early spring.

Lisa:
Yeah, it gets pretty dark.

Shelley:
If I've got a larger area, I always hate to recommend chemicals, but it can be used as a last resort.

Lisa:
Yes, there are a couple of chemicals I could recommmend.  The most effective one is 2-4-D products.  Round-Up can also be used.  But you might have to spray a couple of times.  What they do in prairie situations, is they burn the prairie.  And this is one of the first things that comes up.  Then you can spot treat it, instead of having to broadcast over large areas and maybe take out plants that you didn't want to take out.

Shelley:
That's a good idea, because again, the use of chemicals is never safe.  I mean, the less you can do of that, the better.  Thank you.  I think I'm going to avoid this weed.

Lisa:
That's a great idea.

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