Wild Parsnip – Pastinaca sativa

Wild Parsnip is in the Umbelliferae – the carrot family – and like carrots, the roots are edible.  Wild Parsnips are native to Eurasia, and were introduced to the U.S. in the 1800s.  They are on many states’ noxious weed lists.

One of the reasons Wild Parsnips are such a problem is that they are prolific – producing many seeds, and advancing quickly into areas of native plants.  Another reason is that their sap causes painful blisters on people’s skin when exposed to sunlight.  I have to be very careful when I’m cutting it – I wear gloves, long pants, long sleeves, and cover as much exposed skin as possible.

Here’s my parsnip pulling outfit.

The netting is to keep the gnats away, and also to protect my face from stray pieces of parsnip.

One recent innovation is using velcro to attach my gloves to the sleeves of my shirt.  I used to have trouble protecting my wrists – I’ve gotten several blisters where the cuffs and the gloves didn’t quite meet.

This works perfectly – now my wrists are covered even when I stretch down to pull on a long stem.

 

Wild Parsnip is a biennial, producing a rosette of leaves the first year, and a single flower stalk the second year.  It grows in open areas and wetlands – not in standing water, but in areas with plenty of moisture.

Wild Parsnip flower stalks

Wild Parsnip root

 

Here are some pictures of areas of our wetland that have been invaded by Wild Parsnip.

 

 

 

Native insects nectar at the flowers – like this Baltimore Checkerspot butterfly.

 

There are a few things that attack Wild Parsnip, but so far they don’t seem to make much of a dent in the population.  This is a Black Swallowtail caterpillar.  They will eat Wild Parsnip, but I don’t find them on plants very often.

 

This is a disease called Aster Yellows.  It’s transmitted by hoppers which don’t overwinter here – they fly up from the south in the spring.  So in years when there are lots of those hoppers, there are more diseased Parsnip plants – but not enough.

 

Parsnip Webworms (Depressaria pastinacella) came here from Europe, probably sometime in the 1800s.  They’re the caterpillars of  small moths that eat Wild Parsnip and several related plants, but don’t seem to have enough impact to really affect its spread.

Here’s the caterpillar of the Parsnip webworm.

 

Here it is inside it’s ‘nest’ on a parsnip plant.

 

And here’s an adult Parsnip Webworm moth.

I see the webworms here, but not in great numbers, and they don’t seem to be having an effect on the Parsnip population.

We have about 50 acres of wetland, and there’s parsnip in nearly all of it.  We started on our western border, and we’re slowly working our way east.  I think we’ll always have some parsnip, but I’d love to get it to the point where we only have to spend a few days on control every year.  We’re not there yet!

We’ve discovered two methods of control that seem to work well.

Where there are dense patches of second year plants, Mike mows it just when it’s beginning to come into bloom.  The mowed stems do send out new flower stalks, but they’ve very short, and don’t produce nearly as many seeds as the unmowed stalks.  He mows dense areas for two or three years – usually just once a year – until there are few enough stalks that I can pull them.

Here’s Mike mowing parsnip.

 

Here’s the field after it’s been mowed once.

If he’s feeling really ambitious, he mows a second time, a few weeks later.  That cuts off the second set of flower stalks.

After mowing for a few years, and the density of second year plants is lower, I pull them by hand before they go to seed.  That leaves the other wetland plants to flower.

The roots are large and sometimes branched, so it’s easier to pull them if the ground is wet and soft.

I usually start pulling in mid-June, and finish in mid-July.  Over the season I use 3 pulling techniques, depending on the Parsnips’ stage of development.

(1)  Here’s a small second year plant, with the flowers not yet expanded.  Early in the season, most of the plants look like this.  Once they’re pulled, the flowers won’t continue to open, and no seeds will form.  This makes pulling them much easier – I don’t have to remove the pulled plants from the site.  I just let them drop to the ground as I pull.

Closeup of the unopened flower

 

(2)  As soon as the flower heads start to expand, I have to remove the plants from the site.  At this point, even if the plants have been pulled, the flowers will open, insects will pollinate them, and they’ll make seeds.  Here’s the gator full of pulled Parsnip plants, ready to go to the compost pile.  (Some of the seeds germinate in or around the compost pile.  I check around the pile the following year to be sure I pull or dig up all the seedlings.)

 

(3)  Late in the season, when the seeds are beginning to mature, and the leaves are yellowing, I stop pulling the plants, and just cut off and remove the tops.  At this point most of the plants won’t re-sprout.  This stage doesn’t last long – as soon as the plants start to yellow, the seeds start to mature and dry and drop off.  I have to hurry and get finished before the seeds start dropping off the plants.

When the seeds look like this, the plant is starting to dry up, and I can leave the root in the ground, and just cut the top.

 

This picture shows some very dry seeds – they’re starting to fall off the plant.  It’s still worth cutting and removing as many as I can – it still prevents a lot of new plants from getting started.  But I’m almost at the end of the parsnip control season for this year.

 

Here’s a field in our wetland, where I’m trying to control the parsnip by pulling.

 

This is the same area, later in the day, after I’ve pulled that big clump of Parsnip.

These photos were taken in 2006, the first year I really started seriously trying to control the parsnip.  For several years I didn’t see much progress – it seemed like every year there were just as many plants as there had been the year before.  But finally, in the last year or two (2011, 2012), I’m seeing a difference.  This field took much less time to weed this year – the number of parsnip plants is definitely getting smaller.