Archives

Expert’s Tip: Wild Parsnip — What is it and why should we be concerned about it?

by Ken Schroeder, Portage County UW-Extension Agriculture Agent

Wild Parsnip, Pastinaca sativa, is an invasive member of the carrot family that continues to spread into unmanaged areas throughout Wisconsin. It likes to grow in sunny, grassy areas along roadsides, railroads, and field borders but is not limited to these conditions. Primary means of spread is by seed that can be moved long distances while mowing roadsides after the plant has set seed.

What’s the concern?  The biggest concern isn’t the fact that it is invasive and rapidly spreading but that it will cause burns and blistering of the skin if you come in contact with plant sap in the presence of sunlight. This is known as phytophotodermatitis. Blisters and rashes appear 24 to 48 hours after exposure. Blisters do not spread like poison ivy but are uncomfortable and may leave scars lasting for several months to two years.

Pastinaca_sativa_'wild_parsnip'_2007-06-02_(plant)How do we identify wild parsnip?  The plant is a monocarpic (the plant dies after blooming) perennial and has two growth stages. The first year it produces a non-flowering leafy rosette of pinnately compound leaves with 5 to 15 leaflets.  It looks a lot like celery at this stage.  In the second to third year, it produces a flowering stem four to five feet tall. Stems are grooved, hollow, and have alternately arranged compound leaves with 2 – 5 pairs of opposite, sharply toothed leaflets and petioles that wrap around the stems. Flowers are flat-topped clusters (umbels) of yellow flowers 2 – 6” wide blooming in late spring to mid-summer in Wisconsin. Seed begins to form mid to late July changing from yellow-green to tan as they mature.  Along with the seeds maturing the stems and leaves begin to senesce, turning tan to brown in color.

How do we manage wild parsnip?  Early detection when populations are small allow for pulling or digging.  Be sure to wear gloves, long sleeves, long pants, and safety glasses or face shields to avoid skin contact with the sap.  One can simply cut the taproot with a shovel or spade 1 – 2” below the soil surface.  With larger populations mowing is an option if done after emergence of flower heads, but before seeds enlarge.  Additionally, several chemical options exist.  Be sure to read and follow label directions when using chemicals.  For more detailed management options see the UW-Extension wild parsnip management publication A3924-15 at the Learning Store website https://learningstore.uwex.edu/ .

What can I do as a Master Gardener to help?

  • Know how to identify wild parsnip and report locations at the Wisconsin First Detectors Network website http://fyi.uwex.edu/wifdn/get-involved/report-invasive-species/.  Several options are listed including a downloadable smartphone app.
  • Educate others about the existence and danger of wild parsnip.
  • Carry a sharp shovel or spade with you and when you see only one or a few plants consider cutting off the stems below the soil surface.  As long as they haven’t gone to seed the plants can then be left to die.  Check back the next year to see if additional plants emerge and cut those too.  CAUTION do not do this on private property without getting permission from the property owner.

Additional invasive species information

  • The University of Wisconsin Weed Science website http://fyi.uwex.edu/weedsci/ is a great resource for weed id and management info and has several short YouTube videos to help with identification.

The Wisconsin DNR invasive species website http://dnr.wi.gov/topic/Invasives/ has a wealth of information on not only terrestrial invasive species but aquatic and wetland invasives as well.

Advertisements

Expert’s Tip: New Invasive Species Jumping Worms

Lisa Johnson, Dane Co. UW-Extension Horticulture Educator

 

worms1

These invasive worms jump when handled.

As you are doing yard clean-up this fall, there is yet another new invasive pest to look for, identified in Dane County in October of 2013. Jumping worms (Amynthas spp.) are of Southeast Asian origin and they can be very damaging to soil structure in gardens as well as forest environments. No earthworms are native to Wisconsin—they were all killed off during the Ice Age. We do have 20 European species in the state, however. Earthworms all have negative effects on the forest duff or litter layer, which acts as a protective cover and helps forest floors to retain moisture, insulate tree roots, provide nutrients, prevent erosion, etc. When that litter is eaten by earthworms, the protective cover is removed, exposing the soil and causing erosion, compaction and increased runoff. This disturbance favors the spread of invasive plants such as garlic mustard and buckthorn. Researchers have also documented the negative effects of earthworms on forest regeneration and ground nesting bird populations.

The jumping worm is especially destructive since it lives right in the duff layer rather than lower in the soil profile. Jumping worms tend to outcompete European earthworms to become the only species in forest environments. They consume the layer of leaves and other organic matter on top of the soil faster than other earthworm species. They have been found in Dane, Sheboygan, Jefferson, Waukesha, Milwaukee and Racine counties, and signs of the worms (though no adults) have been noted in 8 other counties. Jumping worms have also been found in some states in the Eastern U.S. We don’t know how long they have been here in Wisconsin, but introduction through contaminated soils or plants is suspected. Since they can spread very quickly, it is important to slow the spread. Best management practices are being developed by the DNR and municipalities. Don’t share plant divisions from your garden or soil if you know you have jumping worms.

Jumping worms are parthenogenetic, producing eggs without the need for a mate, so just one worm can start a new population. Their eggs survive as microscopic cocoons over winter, with all the adults dying in fall. You won’t see the young worms until late June each year, but you will see the ‘soil signature’ from their feeding during the previous season. Jumping worms feed on soil organic matter, leaf litter and mulch and create very grainy-looking and hard little pellets when they excrete. The excretions resemble coffee grounds, and have poor structure for plants to grow in. Also, the worms’ feeding removes the organic matter that plants, fungi and bacteria need for nutrients. Adult jumping worms are 3 to 5 inches long but can grow to up to 7 inches in length. Jumping worms resemble regular earthworms but there are some important differences. Unlike European earthworms, they don’t produce slime and are more gray or brown in color than pink. Their clitellum, the band of lighter-colored tissue near the head, is smooth, not raised like other earthworms and whitish, not pink. It also goes all the way around the body, not just partway, like the European worms. The body is more rigid as well. Jumping worms get their name from their behavior—when handled, they thrash violently, may jump into the air or even shed their tails. They move in a serpentine fashion like snakes, as well.  Check out this video to observe them moving.  After hatching in late June, each worm begins reproducing; their life cycle lasts 60 days, so we can have two generations easily each year. Unfortunately, other than killing any worms you find by placing them in a closed plastic bag in the sun, there are no products labeled to kill them, since soil drenches would also kill beneficial soil organisms. Some products are being tested, but I haven’t heard about any results as of yet.

To report a sighting of jumping worms, email Invasive.Species@wi.gov . For more information and to see photos, visit http://dnr.wi.gov/ and search for the keyword ‘jumping worm’. There is also a great article in Wisconsin Natural Resources that you may want to check out . 

Editor’s note: these worms have also been identified in Outagamie County.