Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
New Invasive Plant Discovered at Rachel Carson National Wildlife Refuge, Maine
Northeast Region, August 2, 2013
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LMRD Biologists Susan Adamowicz points out the perennial pepperweed area.
LMRD Biologists Susan Adamowicz points out the perennial pepperweed area. - Photo Credit: Stephanie Petrus
Perennial pepperweed found at Rachel Carson NWR.
Perennial pepperweed found at Rachel Carson NWR. - Photo Credit: Stephanie Petrus

On July 9, 2013, I was out in the field helping one of our staff members move equipment from the beach dunes when I noticed a plant that looked a lot like the highly invasive perennial pepperweed. The plant’s identification was later confirmed by our salt marsh Land Management Research and Demonstration (LMRD) biologist and Refuge biologist. But what was it doing at the Rachel Carson NWR in Maine? Perennial pepperweed (Lepidium latifolium), is an aggressive non-native plant belonging to the mustard family. This invasive is a significant threat to habitat quality. It spreads not only through seed production, but also through an extensive creeping root system. Once it is established, pepperweed creates a dense, single-species zone, out-competing local flora. A mature plant can reach up to 4 feet in height but generally grows between 1-3 feet. Pepperweed flowers in July, producing small white flowers in dense terminal clusters and has alternating, waxy leaves.

My name is Stephanie Petrus and I came to the Rachel Carson NWR to work as a volunteer intern for the LMRD salt marsh program. The whole Rachel Carson NWR team believes that early detection is a key to successfully controlling the spread of invasive plants. As part of a National Fish and Wildlife Foundation (NFWF) Pulling Together Initiative (PTI) grant obtained by the LMRD program, I was asked to travel to northern Massachusetts to help Mass Audubon with their pepperweed pulling events. The purpose of the grant is to corral pepperweed in northern Massachusetts, prevent its spread to northern New England and train people to help with early detection. During my time in Massachusetts, I worked with Audubon members, volunteers, and high school students to help eradicate pepperweed and spread awareness about the plant. Pepperweed has made a huge impact on biodiversity in the west and Midwest. Biologists in the east are wary of the same effects it may have here. Manual pulling has been a successful control measure in Massachusetts when combined with chemical herbicides. At our refuge in Maine, we keep Rachel Carson close to our hearts, so we do not use chemical herbicides which is why early detection is even more important.
Because I had experience from helping in Massachusetts, I was confident of my identification when I spotted pepperweed on our dune/salt marsh edge. As it turns out, this is the first official sighting of pepperweed in the State of Maine. The patch had an estimated 150 plants and seemed to be established for at least three seasons. We didn’t spot it earlier because that area isn’t well traveled. If it was not for the initiative of the LMRD program and its PTI grant, I would not have been as familiar with pepperweed and the plant may not have been found until it was much more widespread. This experience has taught me that public outreach can make such a big difference. Simply put, the more eyes we have looking for these plants, the greater the chance we have of finding them before they alter our environment beyond our control.


For more information contact:

Susan C. Adamowicz, Ph.D. Kate O’Brien
LMRD Biologist Refuge Biologist Susan_adamowicz@fws.gov Kate_O’Brien@fws.gov

Rachel Carson NWR
321 Port Rd.
Wells, ME 04090

Rachel Carson NWR website
Contact Info: Stephanie Petrus, 207-646-9226, stephanie_petrus@fws.gov
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