KC Weed News - September 2006
 Topics Below
Common reed, a very tall clone-forming wetland grass usually called phragmites, is one of the most widespread plants in the western hemisphere. But it isn’t the same genetic type everywhere it grows. We knew that it was supposed to be native in Washington, but when we saw the extensive stands along the Winchester Wasteway in eastern Washington and the dense monoculture in the created wetland at the 1 st Avenue South Bridge in Seattle, we began to wonder what was going on. We weren’t alone. After collecting samples from our local populations with Greg Haubrich from WSDA for a research project run by Dr. Bernd Blossey at Cornell University, we discovered that all of these rampant populations of phragmites were in fact a non-native type introduced from Europe to the Pacific Northwest and other parts of the United States. It is much more vigorous and invasive than the native type and doesn’t seem to be kept in check by natural enemies. Dr. Blossey has an excellent summary of the morphological differences on his web site: Morphological differences between native and introduced genotypes . The research is ongoing, so if you discover a new population of phragmites, let us know and we can find out if it is native. So far, no populations of native phragmites have been found in King County.
After confirmation that our populations were all the non-native and aggressive type that could have serious impacts on wetlands and waterways, the King County Weed Board decided to aggressively pursue control of this relatively new invader while it was still limited in distribution in our county. So far, we have found only two large populations – one in the wetland by the 1st Avenue South bridge, owned by WSDOT, and one on Kellogg Island in the Duwamish River on Port of Seattle property. There are smaller satellite populations in the Duwamish area, on Vashon Island, in Mercer Slough, in the Lake Washington wetlands along Union Bay, on the Sammamish River and in Auburn, as well as several roadside patches including one very visible patch on I-5 south of downtown. Almost all of the populations are on public land or rights-of-way and this year all of the agencies responsible have been working hard to control these satellite populations.
The large stands at the 1st Avenue South Bridge and on Kellogg Island are very daunting and both will require longer term management plans. Sean MacDougall and Steve Burke from our program have been working with WSDOT and Port of Seattle to come up with management plans and we are happy to report that control plans are underway on both sites beginning this year. Due to the difficulty of control and the nature of the sites, the agencies will be using a variety of methods. Port of Seattle will be using repeated cutting this year and next spring followed by covering and WSDOT will be initially treating the 4 acres at the 1st Avenue South Bridge with the aquatic formulation of glyphosate, followed by other methods as appropriate.
If you are not familiar with this plant, I would recommend a drive down to the 1st Avenue South Bridge on Highway 509. Look west and down to the wetlands along the highway as you travel over the bridge. The very tall grass with large tawny or purplish feathery plumes filling in the wetlands is the plant we are worried about. It is very difficult to confuse this tall grass with anything else when it is full height, except perhaps with pampas grass (a clump forming grass with fluffy white plumes) or reed canary grass (not nearly as tall as phragmites and more yellow-green in color). If you notice any large stands of a very tall grass (up to 12 feet tall), please do not hesitate to give us a call. We are very motivated to find and control all the non-native stands of this plant before it becomes more established in our county. We really don’t want another vigorous invasive spreading along our waterways and wetlands!
For more information, see our website, the WA State Weed Board’s site or Cornell University’s website especially the very helpful chart showing the differences between native and non-native types. Please contact the King County Noxious Weed Program at 206-296-0290 if you think you see phragmites growing in the county or report the site online.
Weeds in Bloom: Noxious Weeds in September
Mostly in Seed but still some Flowers: Purple Loosestrife, Tansy Ragwort, Spotted Knapweed, Policeman’s Helmet, Dalmatian Toadflax
Flowering Now : Floating Primrose-willow (external link), Phragmites/Common Reed, Knotweed, Yellow Nutsedge
Will Flower Later this fall : English Ivy
Seattle Weed Workshop at Northgate Community Center
On Saturday, October 21, from 1:30pm - 3:00pm, we will be holding a free class on “Backyard Invasions: Noxious Weeds in Seattle's Greenspaces” at Seattle’s beautiful new Northgate Community Center.
Invasive plants pose a serious threat to the health of urban streams, forests and natural landscapes. Noxious weed education specialist Sasha Shaw will present a slide show on invasive plants that are threatening community parks, waterways and natural areas. Learn how invasive and noxious weeds spread, where they come from, and what communities can do to stop them from spreading any further. Invasive weeds can seriously degrade a community's natural resources, but if everyone works together, even the toughest neighborhood weed bullies can be stopped! Register at the Northgate Community Center in person or by phone at 206-386-4283. The address is 10510 5th Ave NE , Seattle, WA 98125 .
New Noxious Weed Photo Guide for King County
We are happy to announce that we have a new resource for King County residents. The Citizens Guide to Noxious Weeds is a handy, pocket-sized booklet with photos and information on noxious weeds that are regulated in King County. The booklet explains the State Noxious Weed Law, what King County’s noxious weed program does and what everyone can do to help prevent the spread of new noxious weeds in our county. This booklet will help King County citizens to recognize the noxious weeds that are on our Class A and B lists and to understand their impacts. For your own copy or for larger amounts to distribute at events, please contact Suzanne Rowe at our office at 206-296-0290 or Suzanne.Rowe@kingcounty.gov.
Floating Primrose-willow: Early Detection and Rapid Response In Action
 In 2003, former Noxious Weed Program specialist Ingrid Lundin (now working with DNRP’s Natural Resource Lands Program) was working at the mouth of the Taylor Reach Natural Area near the confluence of Taylor Creek and the Cedar River. Ingrid noticed a bright green yellow flowering aquatic weed spreading in mats over sensitive wetland areas. Ingrid said she knew at once “something just didn’t look right about this plant”.
The Noxious Weed Program identified the plant as a species of Ludwigia in the primrose family. Consulting further with experts including WA State Department of Ecology’s Jenifer Parsons, it was determined that this was a new weed to the state – Ludwigia peploides – floating primrose-willow. This plant is native to South and Central America as well as some other parts of the United State but not in Washington State. It is known to have explosive growth and is creating significant impacts to wetland and aquatic ecosystems in North America and Europe. The King County Noxious Weed Control Board nominated Floating Primrose-willow as a noxious weed to the Washington State Weed Board and it was reviewed and added to the list as a Class A noxious weed this year.
Since the population was discovered, the Noxious Weed Program has been working with the County’s Capital Projects and Natural Resource Lands staff to control the infestation. It has now been reduced to just a few isolated plants. Hopefully it will be totally eradicated in the near future.
The properties at the mouth of Taylor Reach were acquired by the County to protect and restore salmonid habitat. The primary restoration goal is to establish a better connection between the channel and the floodplain including levee setback and riparian and wetland vegetation restoration. In addition to the floating primrose-willow control, careful management of other invasive plants on this site over time will be necessary to achieve long-term restoration success.
Purple Loosestrife on Cottage Lake: Results from State Law, Stewardship and Some Very Helpful Bugs
 When I began my work as a noxious weed inspector in 1997, Cottage Lake was one of the few in the county at that time where purple loosestrife was required for control. In this northeast corner of the county, we felt we had a real chance of stopping the spread of this invasive wetland weed. That year we were only able to survey the county park, which unfortunately had loosestrife in its newly restored wetlands, but we knew there was more around the lake. In 1998, we surveyed the lake and found purple loosestrife on 42 parcels all around the lake. We held a public meeting to explain the impacts and control methods for this plant and started working with property owners on their infestations. Most of the lakeside property owners cut their plants at the base late in the flowering season and this worked pretty well to prevent seed production. Some people were able to dig up their loosestrife, but mostly digging was just not practical. From our canoe, we cut and bagged the hard-to-reach plants that people missed and we helped those landowners who weren’t able to do the work themselves. Almost all of the property owners controlled their loosestrife voluntarily, some even without our asking, and we were able to keep seed production on the lake down to a very small amount each year.
However, the amount of loosestrife stayed pretty steady and this level of effort may have gone on indefinitely if it were not for a stroke of good luck. In 2004, we were excited to see the tell-tale small holes made by Galerucella beetles on the loosestrife leaves in some parts of the lake. As far as we know, no one released purple loosestrife beetles on the lake, so they seem to have flown in from another loosestrife infestation in the area. We had thought the loosestrife wasn’t dense enough to support the beetles. But for the first time, we started to see a decrease in the loosestrife instead of just holding steady. The bugs seemed to tip the balance on the already weakened plants and fewer of them came back the next year. The combination of repeated cutting and beetle damage really started to show results in 2005. This year, only 13 parcels on the lake had purple loosestrife present and the plant density on all of these parcels including the park is very low, with mostly small plants flowering late or not at all. Progress like this is encouraging and shows us that the State Weed Law can be a helpful tool for reducing the impact of a challenging noxious weed such as purple loosestrife. The story also shows how useful biological control is, even in relatively low-density infestations like this one. We can’t walk away yet, but this is one case where the weeds aren’t winning anymore and we have a real chance of long term success.
Invasive Plant Conference: National Experts and Regional Case Studies
There is a great opportunity this month to delve deep into the issues of invasive plants, hear about the latest research, and find out more about specific noxious weed infestations and solutions in this region. If you haven’t already done so, check out the information on the upcoming conference at the University of Washington. It’s called “Meeting the Challenge: Invasive Plants in Pacific Northwest Ecosystems” and it’s being held at the University of Washington Botanic Gardens on September 19 and 20. There are lots of great speakers and presentations, including one by our own Steven Burke, and the poster session will include three King County projects – garlic mustard, milk thistle and garden loosestrife – as well as many other great reports. There will also be a presentation on the Middle Fork Snoqualmie Watershed invasive plant project and be sure to sign up for the field trip following the conference and see this great project up close and personal. For more information and to register, check out the conference website or contact the Conference Coordinator at 206-685-8033 or jrobins@u.washington.edu.
It’s that time of year again – Do the Puyallup. Sometime between September 8 and 24, make sure to head out to Puyallup for the corn dogs and the scary rides and when you need a break, stop by the Pierce County-King County Noxious Weed Booth. This year, our staff will be there to talk about King County weeds on Sept. 8, 14, 22, 23, and 24. The rest of the fair, Pierce County staff will be there to answer your noxious weed questions and we’ll have plenty of King County weed booklets, weed lists and fact sheets for you to pick up throughout the fair.
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