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KC Weed News - February 2007 (PDF Version for Printing) TOPICS BELOW
Our weed of the month may have escaped your notice so far. Its small, inconspicuous green flowers that are starting to open this month will probably not draw your attention either. It has quietly been moving out of gardens and into local woodlands, but without the obvious problems of other escaped ornamentals like English ivy or herb Robert. It doesn’t climb up trees and it doesn’t carpet the ground like stinky Bob (at least not yet). However, it has created considerable problems in the coastal forests of southern British Columbia and the San Juan Islands, creating large, dense infestations in some of the few remaining stands of Garry oak woodlands and Madrone forests. We still don’t know the full potential impact of spurge laurel. However, it is clear that it can damage some of the state’s most fragile lowland forest types and that stopping its spread now can prevent considerable damage to this important natural resource. In King County, there are numerous small populations of spurge laurel, but so far we haven’t found any populations that are particularly alarming. What we have seen are mostly scattered patches or isolated plants in urban parks, but we are still gathering information. According to Ella Elman with Seattle Urban Nature, there are 27 parks in Seattle that have spurge laurel. The average population size is about 3000 sq ft and the total infested area for all the parks is less than 2 acres. In general, they are finding it scattered in a lot of places, but not taking over any areas. Personally, I have noticed this plant often in urban parks in the county, but never in large numbers and usually just a few plants by themselves. I even found one solitary escapee spurge laurel in my own backyard, not far from where my volunteer butterfly bush seedling showed up. Because of berries that birds enjoy, this plant is spread far from the gardens where it was planted. And because spurge laurel is very tolerant of low-light and dry soil, it has a decided advantage in many urban forests, where it can peacefully co-exist with other invasives such as English laurel, ivy and holly. Spurge laurel is not a spurge or a laurel as you might think from its name. However, its shiny, thick, evergreen leaves might remind you of cherry laurel and it probably gets its spurge name from the way its leaves whorl around the top of the stems and the greenish color of its flowers. Spurge laurel also has health hazards like its namesakes. The whole plant, including the berries, is poisonous to people and some animals, and the sap can cause contact dermatitis. Spurge laurel usually grows to only about 2 to 4 feet tall and is more or less upright. Arthur Lee Jacobson ( Wild Plants of Greater Seattle) writes that it grows in the shape of a little tree, with stout twigs and a cluster of leaves near the top. He also explains that the stems stink when cut or damaged and the flowers are only really fragrant at night when they are attracting moths. There are photos and more information on identification, ecology and control on our spurge laurel web page. f you notice this plant growing in an alarming way or in a remote natural area, please contact our program or the land owner. Although control is not required for this non-designate noxious weed in King County, we are gathering information on distribution and impacts and we do want to respond quickly if there is a need. You can call us at 206-296-0290, send an email to sasha shaw or use our online infestation form. Pull over-wintering weeds now while the soil is soft and moist. Rosettes of weeds like knapweed, tansy ragwort, garlic mustard, milk thistle, and poison-hemlock are easy to find now and the roots will come out without breaking. Late winter, while the soil is moist and not much is growing out there, is a great time to find and pull these noxious weeds. Keep a lookout for gorse, starting to flower this month . Keep your eyes out for the fragrant yellow flower clusters on large, spiny bushes. Expect to find this plant along coastal areas and in forests on well-drained soils. Pulling or digging up this plant is possible while the soil is loose but you may need a weed wrench and heavy duty gloves. Control English ivy before the berries mature and while the soil is loose and soft . English ivy is easiest to find now before deciduous trees leaf out. Also, it causes less damage to native forest plants to control ivy now before woodland flowers and shrubs really get going (which will be soon now - the Indian plum buds are already starting to break). Just be careful around storm-damaged trees – never pull ivy down from the upper parts of a tree since this might injure the tree and will most certainly injure you if branches fall off. Just pry the vines off the bark of the tree up to where you can comfortably reach and all the way down to the ground. On January 17, the King County Weed Board approved the following changes to the King County Noxious Weed List:
The name change for spotted knapweed is due to recent taxonomic research on North American populations of this species. The research showed that all our populations belong to the central European-western Asian species Centaurea stoebe subsp. micranthos. Interestingly, this species is invasive in western and northern Europe as well as here. The new weeds were all added to our non-designate list which means that control is recommended but not required. Our goals for all three new noxious weeds are: to educate the public about their impacts, recommend that people don’t plant them, give advice on how to remove them especially where they have escaped into natural areas, and continue to collect information on distribution and impacts in King County. Please contact us if you have any observations on these three weeds in the county, especially if you notice any of them having a significant impact on a natural area. We have been collecting information on yellow archangel for the past few years so we have fairly good data on its distribution in natural areas. Although it is mostly found near urban areas, it is also spreading and having an impact on natural forest habitats. It is also very clear that yellow archangel is almost always spread by cuttings or as yard waste into natural areas. This highlights the critical importance of proper disposal of yard waste – dumping into parks and ravines is never a good idea. Even though it will eventually break down into compost, dumped yard waste can also cause great damage by spreading invasive ornamentals into natural areas. The other two additions – spurge laurel and common fennel – are Class B weeds on the State Weed List. These species have the potential to seriously impact resources in Washington and they are still limited in distribution in some counties. Control of both of these plants is required for some neighboring counties, so it is important to check with the State Weed Board for more information if you own land outside of King County. In this county, our Weed Board feels that there are too many escaped populations of both of these new Class B weeds to require control. Also, we have only observed these plants escaping in cities near where they were planted, so it doesn’t appear that they are threatening natural resources in our county. However, we are also very interested in gathering more information on both of these species, so please contact us with your observations and thoughts on spurge laurel and common fennel in King County. For more information or to report escaped populations of these new noxious weeds, contact Sasha Shaw by email at the King County Noxious Weed Control Program, use our online infestation form, or call the office at 206-296-0290. For local, county or state agencies or non-profit organizations with Class A noxious weed infestations, there is an opportunity to get a little financial help. The Washington State Noxious Weed Control Board is soliciting proposals for projects to eradicate Class A Noxious Weeds in the State. A total of $15,000 was made available in the previous fiscal year and the Board anticipates providing a similar amount in the fiscal year that begins July 1, 2007 and ends June 30, 2008 (although the availability of funding cannot be guaranteed). Proposals are due March 8, 2007. For more information, contact Steve McGonigal (SMcGonigal@agr.wa.gov) at the Washington State Noxious Weed Control Board, (360) 902-2053. In addition to experiencing spring early, you can come get answers to your noxious weed questions at the upcoming Northwest Flower and Garden Show, February 14 to 18 at the Convention Center in downtown Seattle. This year’s show features a more compact layout so all the booths will be on the same floor. You will be able to find King County Noxious Weed staff and materials at two booths. The Washington State Noxious Weed Board booth (next to the USDA/WSDA Plant Inspections table) will feature noxious weeds listed throughout the state as well as alternatives to invasive ornamentals. The King County Department of Natural Resources and Parks display will show how Naturescaping can be a part of all of our yards and will include an invasive weed display to show what we should avoid planting or watch out for in our yards. Hope to see you there! On March 15 and 16, WSWS is holding a special symposium in Portland on one of the worst weeds impacting our county – invasive knotweed. This symposium is being held in conjunction with the annual conference on weed science also being held in Portland. It will feature presentations by researchers from Europe and the United States as well as presentations by local experts and land managers who have been working on understanding and controlling this difficult plant and will report on its biology, ecology and control. The cost is $75 (or $50 if you are already attending the WSWS annual conference). Check out the WSWS website for more information. The noxious weed program will once again offer two workshops for vegetation management crews and others who need to identify and manage noxious weeds as part of their work. Using live specimens and slides, we will focus on how to identify and control noxious weeds that are designated for control in King County. In addition, we will have guest speakers present useful information on issues of concern to pesticide applicators and vegetation managers. We expect to offer WSDA pesticide recertification credits for both of these classes.
To register and receive updates on the class agenda, please contact Sasha Shaw at 206-263-6468 or sasha.shaw@kingcounty.gov. Please feel free to pass this information on to others who may be interested as well. Both classes are free and open to the public. If you are ready to take the next step in using livestock grazing to manage weed populations, you might want to take a look at this new resource. An announcement in the Western Society of Weed Science newsletter has this to say about the handbook: “targeted grazing by livestock is being rediscovered and honed as an amiable and effective tool to address contemporary vegetation management challenges, like controlling invasive exotic weeds, reducing fire risk in the wildland-urban interface, and finding chemical-free ways to control weeds in organic agriculture”. They go on to say that this handbook outlines the basics of grazing for vegetation management and “represents a compilation of the latest research on harnessing livestock to graze targeted vegetation in ways that improve the function and appearance of a wide variety of landscapes”. The handbook was created through funding from the National Sheep Industry Association and the American Sheep Industry Association (ASI) and is available on-line at: http://www.cnr.uidaho.edu/rx-grazing/Handbook.htm. Printed copies of the handbook will be available through ASI (info@sheepusa.org) for $25 in March 2007. The King County Noxious Weed Program is teaming up with Mary Maier, King County Basin Steward for the Bear Creek Basin, and EarthCorps to start work on a riparian habitat restoration project on Cottage Lake Creek. This salmon-bearing tributary of Bear Creek is under increasing pressure from a host of invasive species. In addition to the usual suspects – blackberry, ivy, some knotweed and yellow flag iris – this creek has some of the densest infestations of bittersweet nightshade and orange jewelweed found anywhere in our area. These two plants are growing out into the creek bed where they are interfering with water flow and fish passage as well as out-competing more beneficial native riparian species. Most of Cottage Lake Creek is privately owned so we will be working to educate property owners about their creek and to invite them to participate in restoring the creek to enhance fish habitat and water quality. If you are interested in finding out more, please contact Sasha Shaw at 206-296-0290 or sasha.shaw@kingcounty.gov or Mary Maier at 206-296-1914 or mary.maier@kingcounty.gov. December 2006 Program offices are located at 201 S. Jackson St., Suite 600, Seattle, WA 98104. To contact a staff member at the King County Noxious Weed Control Program, please call 206-296-0290 or by reach them by email. |
| Please direct questions & comments regarding noxious weeds to Program Staff, King County Noxious Weed Control Program.
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Updated: February 2, 2007 |
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