Silent Invaders

July 20th, 2016 by Donna McBain Evans

Imagine you see that a campfire has ignited some of the dry leaf litter nearby and no one but you is around.  Most of us would know enough to either try to put the fire out, or quickly alert officials to get to the scene.  With such early detection and quick action, it is quite possible to avoid an out of control fire that burns thousands of acres.

This “early detection rapid response” is exactly what some scientists hope will soon be commonplace when it comes to a different form of habitat destruction– invasion of native ecosystems by non-native plants.  Invasion of natural ecosystems by non-native species may not be as quick as fire, but  the damage caused by fast-growing species can result in all the same kinds of dramatic long term changes—changes in soil chemistry, crowding out of native plants, altering natural physical characteristics such as fire and flooding regimes and introducing pathogens.

Invasive species Japanese knotweed alongside highway.

Invasive species Japanese knotweed alongside highway.

It might surprise you that invasive plants are such a big worry.  But they are a serious problem for land managers, agriculturalists and local governments, costing an estimated $120 billion annually across the country for all types of invasives. Almost half of all the threatened or endangered species in the US are in jeopardy precisely due to competition or predation by invasive species.

In Washington, the Pacific Northwest-Invasive Plant Council is taking a lead in tackling this problem.  Lizbeth Seebacher, a PhD specializing in invasive species biology, works with the WA Department of Ecology and also serves on the Board of the Pacific Northwest-Invasive Plant Council (PNW-IPC).

“A grant from the National Fish and Wildlife Foundation in 2011 and subsequent grants from the National Forest Foundation and the WA Departmentt of Agriculture, helped jumpstart a program we call EDRR, or Early Detection Rapid Response,” says Seebacher.  “These grants have allowed us to establish a citizen science program to identify, monitor and report invasive plants on an integrated GPS mapping program, a program called EDDMapS.”

Seebacher’s colleague, Julie Combs, directs the program which consists of several hundred citizen scientist volunteers who adopt an area or trail and regularly hike there to identify problems and report them.

The PNW-IPC coordinates with the U.S. Fish and Wildlife Service, the Park Service, King County, the Department of Agriculture, the Noxious Weed Board and many other agencies.  The goal is to identify problem species and provide a coordinated system for identifying areas of infestation and where spread may be rapid. When citizen scientists find a new outbreak of invasives, it is quickly reported and evaluated.

“Rapid response to a new infestation can be critical, notes Seebacher, “because eradication efforts are most successful in areas under a few acres.”  After that, she says, costs can skyrocket.


UW Botanic Gardens creates home for Invasive Plant Council

For many years, the idea of tasking a specific group to take on the challenge of taming invasive plants floundered in a sea of bureaucracy and lack of funding. Fortunately, in 2006 the UW Botanic Gardens sponsored a conference on invasive plants, with now Director Dr. Sarah Reichard leading the charge.

“Because of my involvement on invasive plant species on a national level, I have been invited to speak at the annual meetings of a number of similar non-profit organizations in Florida, California, North Caroline, and other areas” recall Reichard. There was an attempt to start a council here in the mid-1990s, but despite best efforts, it went dormant in 1997. She knew how valuable they could be in partnering with federal, state, and local governments.

In 2006, Reichard was able to secure a US Forest Service grant to bring together an array of scientists from throughout the Northwest doing important work on invasive species eradication, in a conference held at the Center for Urban Horticulture in which Seebacher was hired to work. “There was great synergy at the conference,” she notes, “and the federal funding allowed us to establish a local committee affiliated with the national Association of Invasive Plant Councils.” The second afternoon was dedicated to a lively discussion of what the PNW-IPC could be.

Reichard was also responsible for getting approvals to house the local plant council at the UW Botanic Garden, where she is now Director.

“Thanks to energetic scientists like Julie (Combs) and Lizbeth (Seebacher),” says Reichard, “we have a vibrant local invasive species council, excellent collaboration with agencies and hundreds of citizen volunteers who are working to keep invasives out of our natural lands.”

Lovely Villain

Forest overgrown with English Ivy

Forest overgrown with English Ivy

Once prized for its graceful presence decorating brick edifices, English Ivy (Hedera helix) has become one of the most familiar invasive plants in our region. It is actually a European native species on the list of noxious weeds in several states, including Washington State.  The qualities that initially made English Ivy a popular ornamental are the same ones that make it invasive in the right environment—it grows rapidly, needs little light or water once established and is extremely hardy—it forms dense mats on the ground and can climb up trees and shrubs.  English ivy can choke off life in native shrubs by preventing light from reaching the shrub due to the density of ivy.  The sheer weight of the ivy can weaken the plant it has grown on and make it more susceptible to blow-down and disease.

The clusters of black berries are eaten and spread by birds which makes dispersal easy and widespread.  In Stanley Park in Vancouver B.C., for example, 700 volunteers removed more than 20,000 square meters of ivy in a recent work weekend.  Despite this comprehensive effort, scientists estimate that it will take 50 years to rid Stanley Park of this invasive pest!

An Alliance with Commercial Nurseries

GardenWiseThere are many sources responsible for introducing invasive species into natural ecosystems, says Seebacher.  Invasives can arrive as seed in agricultural products, or on shipments from overseas.  In the past, officials in the highway departments selected median strip plants for their resilience and adaptable nature, not recognizing at the time the threat it might pose to native ecosystems.

“We are trying to limit the sources of infestation,” says Seebacher, “and an important ally in this effort are local nurseries.”

“So our next big task is to create a Nursery Certification Program,” she says.  The PNW-IPC will be developing a list of species they will ask nurseries not to sell because of the high potential for that plant to become an invasive ‘villain’.  The scientists can also provide ideas for alternate species for nurseries to sell with many of the same decorative characteristics but fewer of the negative consequences for the environment.

“Most home gardeners would not want to be a part of propagating aggressive invasives into the environment,” Seebacher notes.  “This program will help everyone play a part in keeping these costly pests from spreading in our natural landscapes.”


Student Spotlight: Daniel Sorensen

March 18th, 2016 by Donna McBain Evans

Dan_Sorenson_1Daniel Sorensen is a graduate student at the UW School of Environmental and Forest Sciences, working in the lab of UW Botanic Gardens Director, Sarah Reichard, and researching the risk of invasion across Washington and Oregon of 2 two closely related grasses in the genus Cortaderia – pampas grass and jubata grass. Daniel works as the Integrated Pest Management (IPM) and Sustainability Coordinator for UW Grounds Management, and in that role he helps manage invasive species in the Union Bay Natural Area along with UW Botanic Gardens staff.  He is also a student member of the Arboretum Botanic Garden Committee.

Daniel grew up on Long Island in NY, close to the ocean and the salt marshes along the south shore. Family vacations–swimming, hiking and getting lost in the woods of Northern Vermont–sowed Daniel’s love for plants and nature.  Daniel earned a BS from the State University of New York, College of Environmental Science and Forestry, in Syracuse NY.  He also worked in several states doing ecological restoration, natural resources management, and invasive plant management.

Starting a master’s program at the UW is what ultimately brought Daniel to Seattle, although he had longed to live in the Pacific Northwest.  He enjoys exploring Seattle neighborhoods by bicycle, hiking and camping the in the Cascades and Olympics, and going to antique/thrift stores to find vintage Pyrex for his collection. He also enjoys gardening, growing his own food, canning and being surrounded by plants inside his home.

Daniel’s favorite classes are Plant Ecophysiology and Landscape Plant Recognition. Plant Ecophysiology makes connections between the internal working of the plant with external influences in the landscape; it taught him how to ask research questions and set up experiments to answer those questions. Landscape Plant Recognition was a race to memorize the scientific names and identify over 250 plants in one quarter.

Daniel now gives talks and workshops for the UW Botanic Gardens Adult Education Program.

Although Daniel is often busy with classes and work on campus, he often bikes over to the Center for Urban Horticulture for a class or just to spend time in Elisabeth C. Miller Library where he loves “being surrounded by the community of professional staff, faculty, students, and volunteers on campus and UW Botanic Gardens.”

Daniel also loves to visit the Washington Park Arboretum to “get lost under the trees” of the Woodland Gardens, or go paddling in the marshes at the Union Bay Natural Area.

No one plant can be considered Daniel’s favorite, this changes seasonally and sometimes daily. With that said, one his favorite plants from his time in the northeast is Northern spice bush- Lindera benzoin– this small understory shrub has a delightful smell found in the leaves, stems, and fruit (hence its common name) but its small yellow blooms are the reason it is his favorite northeast plant. These small blooms are one of the first bit of color to in early spring and a dense stand of spicebush can glow strong against the drab brown and gray backdrop of the deciduous woodlands in the Northeast. “When I would see the spice bush in flower,” he says in glee, “I knew winter was definitely over!”


Take Back Your Backyard!

July 18th, 2013 by Sasha McGuire, Education Program Assistant
Removing Ivy on a Steep Slope

Removing Ivy on a Steep Slope

Overgrown yard got you down?

Does the dog keep getting lost in the ivy?

Are you tired of not being able to see to the end of the yard?

Learn how to take control of your unruly backyard in this Saturday class. Instructor Rodney Pond will introduce you to the invasive species commonly found in Seattle yards, and show you how to get rid of them (permanently!). In addition, you will learn about what plants will be safe to add to your backyard to return it to the oasis of peace and relaxation it once was.

Are you intimidated by the idea of working on your unruly ravine? This class will also teach home and property owners how to safely remove plants from and work on steep slopes.

Join us for Backyard Restoration!
Saturday, July 27 from 9:30am-2pm
UW Botanic Gardens, Center for Urban Horticulture, Douglas Classroom
3501 NE 41st, Seattle, WA 98195

Cost: $50; $60 after July 20th
Register Online or Call us at (206) 685-8033



Get crafty with our upcoming Garden Craft Series!

Garden Craft: Hanging Glassglass art1
Saturday, August 24, 9-11am
Cost $55; $60 after August 17

Learn how to create reclaimed glass works of art in this introductory class. Use stained glass and wire to create whimsical pieces for any garden or window and take with you not only your creation, but the knowledge of how to do it at home.



potato printGarden Craft: Potato Printmaking
Saturday, September 7, 10am-12pm
Cost: $25; $30 after August 31

Think printing with potatoes is just for kids?  Well, kids do enjoy it, but now adults can too! Learn how to print on cloth or paper with any type of potato. Cheap and elegant gifts are at your fingertips! This is an introductory class; all levels and ages are welcome.




Trees Cheer for Community Volunteers!

April 30th, 2013 by UWBG Horticulturist

As we bid adieu to relentless April showers, let’s also praise a fond farewell to over 300 relentless April community service volunteers that helped support the stewardship of our beautiful botanic gardens. Because of them, May flowers have never looked and smelled soooo good.

Student Conservation Association 2013 Earth Day at the Washington Park Arboretum. Photo curtesy of

Student Conservation Association 2013 Earth Day at the Washington Park Arboretum. Photo curtesy of

The 3 Big April events:

    1. April 13, Earth Day in the Arboretum w/ Student Conservation Association – see photos
    2. April 19, UW Partners w/ Starbucks for Earth Day at CUH and Farm- see video

  1.  April 25, Ivy Out w/ Seattle Prep  – a few photos below
Seattle Prep students removing ivy in the hollies

Seattle Prep students removing ivy in the hollies

Seattle Prep students removing ivy in Pinetum

Seattle Prep students removing ivy in Pinetum









A few of the impressive metrics:

  • Over 22,000 sq feet of invasive plants removed (ivy and blackberry)!
  • Over 60 yrds of mulch spread!
  • Over 1500 native plants planted!
  • Over 20 yrds of ivy hauled!

SPRAY NOTIFICATION: Garden Loosestrife, Initial Applications July 26 through August 9

August 4th, 2011 by UWBG Horticulturist

UW Botanic Gardens has begun its 5th and final year of the 5yr Dept. of Ecology, Garden Loostrife eradication project.

 Our contractor, NW Aquatic Eco-Systems, has scheduled initial  spray applications to commence on July 26 and continue through first week of August.  Postings of project and current spray dates are located at all public accessible waterfront locations.  There will be a final follow-up application in September.

Lysimachia vulgaris, Garden Loosestrife, a non-native wetland species is invasive in this area. State listed as a class B noxious weed, it requires control by the land manager UW Botanic Gardens as mandated by King County Noxious Weed Control Board.



Treatment includes: 

  •  Approximately 5 miles of shoreline property bordering Union Bay including Foster and Marsh Islands in the Washington Park Arboretum
  • An initial and follow up spray application to occur between July 15 and October 1
  •  Both shoreline and land side application of the herbicide Habitat (imazapyr), a selective broadleaf herbicide. 
    •  Non toxic to fish and their food web.
    •  No significant risk to birds or mammals


Aquatic Weed Symposium – July 13, 2011

June 7th, 2011 by UWBG Horticulturist

A loosestrife by any other name. . .

If you have trouble remembering this plant’s name, you might try thinking of the strife it has let loose on our wetlands.

In 2009, the Department of Ecology awarded the UW Botanic Gardens a 5-year grant for the control of garden loosestrife (Lysimachia vulgaris), a class B noxious weed mandated for control by the King County Noxious Weed Control Board. Now we’re hosting a symposium featuring the latest observations and expertise on aquatic weed management.

In his keynote address, Steve Manning, founder and president of Invasive Plant Control, Inc., will present economically and environmentally sound techniques for controlling invasive aquatic weeds. You’ll also hear from King County Noxious Weed Specialist Katie Messick and representatives from the UW Botanic Gardens and Seattle Parks Department. The afternoon will be devoted to a kayak or walking tour (your choice) through Lake Washington’s wetlands, one of garden loosestrife’s primary haunts in this region.

Designed for professional audiences, this symposium is open to everyone interested in aquatic weeds and their control.

Managing Aquatic Weeds: Challenges and Opportunities
Wednesday, July 13, 9:00 AM-3:30 PM
Graham Visitors Center, Washington Park Arboretum, 2300 Arboretum Dr. E, Seattle
Professional Credits: WSDA, WSNLA (pending)
Symposium with Kayak Tour, $55; Symposium with Walking Tour, $30
Box lunch included when you register by July 10: 206-685-8033 or online

A successful season of restoration in UBNA!

May 29th, 2011 by Jake Milofsky - UBNA RA

This spring quarter wrapped up a wonderful season of restoration events in the Union Bay Natural Area, with fantastic progress being made on several projects.  Tallying 177 individual visits in the spring quarter, students and community members collectively donated over 400 hours of their time to the restoration efforts being made in UBNA!

The northern end of Yesler Swamp saw a major improvement with the removal of a large monoculture of Himalayan blackberry.  UW students and the UWBG partnered with the Friends of Yesler Swamp to complete this work and install a suite of native plants including Indian plum, red-flowering currant, snowberry, Douglas hawthorne, ocean spray and live willow stakes.  Maintenance will continue in the coming months as volunteers return to weed this area and support the growth of these newly installed plants.


A community volunteer helps remove bindweed from live willow stakes in Yesler Swamp

A large amount of effort was put forth this season in the newly established woodland at the western end of Wahkiakum Lane as well.  What had seemed like an impenetrable sea of Himalayan blackberry during the winter quarter was tamed by the efforts of many students in UW’s Environmental Science course.  As they supplemented their course work with these service learning opportunities in ecological restoration, they also saw many native species appear from below the blackberry as they cut, pulled, and dug it out of the ground.


A big thanks goes out to everyone who participated in this year’s efforts!

Garden Loosestrife – Spray Application Scheduled 9/22

September 14th, 2010 by UWBG Horticulturist

UWBG IPM staff will be out on Union Bay, Wednesday, September 22nd, w/ spray contractor NW Aquatic Eco-Systems. All canoe landings and shoreline trailheads will be posted. This is the second of  two  follow-up spray applications in our effort to control the class A noxious weed, Garden Loosestrife.

Garden Loosestrife Spray Scheduled – Wed., August 18, 2010

August 13th, 2010 by UWBG Horticulturist

Garden Loosestrife (GL) control contractor, NW Aquatic Ecosystems, along with UW Botanic Garden IPM staff, will complete initial 2010 treatment on Wednesday, August 18th. The  Waterfront Trail between Foster Island and MOHAI will be closed early am to public temporarily for contractor access to GL growing near the trail. Signs will be posted on barricades at both trailhead entrances and also staffed during spray period to avoid public breaching the barricades. Trail will be reopened once material has dried on foliage. The remainder applications will be accomplished via boat in and around Marsh and other islands and inlets throughout UW Botanic Gardens managed Union Bay shorelines.

Scheduled pm Kayak tours will not be disrupted. Applications within tour boundaries will be completed in am.

There will be a follow-up treatment later in September. Notice will go out as soon as date is set.

For further information, call 206-543-8800

Invasive Garden Loosestrife Spraying to Restart

July 29th, 2010 by UWBG Horticulturist

Lysimachia vulgaris imageFor a second year, Northwest Aquatic Eco-Systems along with UW Botanic Garden will begin spray work to control Lysimachia vulgaris (garden loosestrife), a state-listed noxious weed occurring along Union Bay shorelines including the Union Bay Natural Area and the Arboretum’s Foster and Marsh Islands the first week of August.  King County requires control of this aggressive and invasive weed, which poses a serious threat to the native character of area wetlands. In 2009, DoE provided a 5-year grant for $75,000 to fund loosestrife control.

In mid-July members of King County’s Noxious Weed Control Program and UW Botanic Gardens staff mapped the extent of the weed in the areas listed above.  Comparison of the maps from year 1 to year 2 demonstrated slight control had taken place.  Once again the weed will be controlled with an aquatically approved herbicide by the contractor, Northwest Aquatic Eco-Systems using airboats and other specialized equipment.

King County Garden Loosestrife Fact Sheet