KC Weed News - March 2012(PDF Version for Printing) Topics Below Weed of the Month: Multiflora Rose (Rosa multiflora), a Weed of Concern in King County, WashingtonMultiflora rose is well known in much of the eastern and central United States as a thorny invader of pastures and roadsides, but is less well known here in western Washington. In some ways, it is similar to our ever-present Himalayan blackberry and may even compete with that plant for space in our fields and roadsides. However, multiflora rose is equally capable of creating thorny thickets, clambering up the lower branches of trees, and out-competing native plants. It has been seen growing quite well in places where Himalayan blackberry and other invasive plants were growing as well, and seems to be able to hold its own in those conditions.
Originally from Asia, this tough rose species was first used in the United States as root stock for ornamental roses. As people became aware of its toughness and dense, thorny growth, it was also used as a living fence along fields and roadsides. It was especially useful in highway medians where its dense growth was useful to reduce headlight glare and act as a crash barrier. Unfortunately, this useful plant was also highly invasive and soon spread so extensively into pastures, natural areas, streamsides and vacant lands that its problems outweighed its benefits.
Identification of multiflora rose is a bit tricky since there are so many varieties and species of rose both in landscaping and growing wild. The overall growth habit of multiflora rose is a combination of thicket-forming arching canes that root at the tip (similar to blackberry) and climbing vines that can reach up into the lower branches of trees. In a field, looks for dense mounds or thickets, but in a wooded area or along a stream, look for a climbing rose that covers the trunk and branches of the trees. The leaves are made up of pairs of deciduous leaflets similar to many rose species (there are usually 5-11 leaflets). The base of the leaf stem is distinctively fringed (look for the fringe where the group of leaflets attaches to the main stem). Another key feature is large clusters of numerous small, bright red rosehips that become leathery and persist over the winter. The flowers are fragrant and have 5 petals that are notched and either white or light pink. The stems often have curved thorns but can also be thornless. To make sure you are identifying multiflora rose correctly, make sure to look for a combination of characteristics –arching and/or climbing stems, a fringe at the base of the leaf stem, and clusters of numerous, small red rosehips (or large clusters of small rose flowers in the spring/summer).
Multiflora rose has been planted less often in our area than in the Midwest and eastern United States, so it hasn’t had as many opportunities to spread. However, it has been used along some highway medians and landscaped areas, so it is likely only a matter of time before we start seeing more multiflora rose as it begins to move beyond where it was planted. Currently, we know of escaped populations along Issaquah Creek, Soos Creek and Cottage Lake Creek, as well as an expanding population along I-90 near Issaquah where it was likely introduced ten or twenty years ago. Because this plant is not that widespread, we are interested in gathering more information about where it is growing outside of cultivation, any impacts it might be having, and any successes or problems anyone is having controlling it. If you would like to share information on multiflora rose in King County, or for more information on this plant, please contact us at noxious.weeds@kingcounty.gov or 206-296-0290. Weed Tips for MarchIt’s garlic mustard time. Garlic mustard rosettes have been waiting all winter for their March growth spurt and will be flowering before you know it. If you had garlic mustard last year, go back to the same places and look for rosettes now to plan how to control them. Be sure to report it if you find any new populations of garlic mustard or contact us if you would like help planning your control work for the year! Check pastures for toxic weeds. Animals will be more likely to graze poisonous plants if the grasses are still too short or sparse, so check fields before setting animals out. Look for rosettes of tansy ragwort, milk thistle, and poison-hemlock and control them before letting the animals graze. For information on other poisonous pasture plants, contact your local extension office or conservation district. A handy summary of poisonous plants in western Washington can be found on our brochures page. It's a good time to pull Scotch broom. The weather is mild and the soil is still nice and moist, making weed pulling easier than in the heat of the summer. Scotch broom starts flowering this month, but there’s plenty of time to pull it before the seed pods form in July or August. If you are in King County, we have weed wrenches you can borrow, but they get pretty popular this time of year so plan ahead. Call us at 206-296-0290 to reserve one for a week or two and then come down to our office by the Seattle train station to pick it up. If you haven’t used a weed wrench before, don’t worry, it’s easy to learn how. Keep an eye out for spurge laurel, flowering this month. You might not notice the small greenish flowers tucked under the leaves. In fact, if you come across a stray spurge laurel plant, you might think you are looking at a small rhododendron or an odd-looking cherry laurel plant. But it is neither. This tough to control, garden escapee is actually pretty common in urban greenspaces and parks in King County, but it is often overlooked until it grows into a large infestation. Because it is toxic and can be irritating to your skin, make sure you wear gloves when removing this plant. There is an excellent description of spurge laurel in a recent blog post out of the Wallingford neighborhood in Seattle: http://blog.seattlepi.com/wallingford/2012/03/02/wallingford-weed/. Look out for gorse, also flowering this month (and don’t fall in one like Winnie the Pooh). Watch for large, spiny bushes with yellow Scotch broom-like flowers densely clustered on the spiny green stems. Did I mention that gorse has big spines? They are hard to miss and painful to experience. We only know of a few locations of gorse in King County, but there may be more lurking in the woods or along the shorelines of Puget Sound. Pulling or digging up this plant is possible while the soil is loose, but you may need a weed wrench or similar tool and make sure to wear rugged clothes and heavy duty gloves. Watch out for birds in blackberry thickets. If you are looking for a good reason to procrastinate your blackberry removal, you can say “it’s for the birds”. Many birds are starting to nest this month and blackberry thickets are a popular place for some bird species. For areas that provide important bird habitat (especially where there are few alternatives near by), the Green Seattle Partnership makes the very good recommendation that you consider refraining from large blackberry removal projects during the nesting season (mid-March to the end of June). If you are removing blackberries this time of year, consider removing only about a quarter of the infestation at a time. This gives the birds time to find other options. Look for rosettes where you controlled weeds last year. March is a good time to look for low-growing rosettes of biennial and perennial weeds, while grass and other plants are still short. Some of the weeds to check for this month or in early April include garlic mustard, milk thistle, tansy ragwort, bull thistle, poison-hemlock, giant hogweed, spotted knapweed and diffuse knapweed. Use a trowel or fork tool to loosen the soil and dig up isolated plants or, if there is too much to control manually, consider whether it might be more cost-effective to spray larger infestations, if the site is appropriate for herbicide use. Younger plants are more susceptible and lower rates can be used to reduce overall herbicide use. Please contact us for more information specific to your site and weed. Three New Species on the King County Weed List At the annual weed list hearing held in January, the King County Noxious Weed Control Board officially adopted the 2012 King County Noxious Weed List. There are three new species on the list. Oriental clematis is required for control because it is a Class A weed on the State Noxious Weed List; the other two new species are recommended for control but not required. Tree-of-heaven is a Class C Noxious Weed on the state weed list and is non-regulated in King County. Multiflora rose is a King County Weed of Concern, and is not regulated under the State Noxious Weed Law. There have been reports of Oriental clematis being used in gardens, but so far we haven’t discovered any escaped populations of this yellow-flowered clematis in King County. Both tree-of-heaven and multiflora rose have naturalized in King County, although not to the extent that they have in other parts of the country. If it is feasible to remove these species as part of a restoration or vegetation management project, then it is definitely a good idea and will help reduce the further spread of these species in our area. Ivy-Free Vashon holds Kick-Off Event on March 24English ivy on Vashon is getting a tough new adversary. Ivy-Free Vashon is a coalition of islanders who are organizing themselves to fight back again the ivy taking over the island’s trees. At their kick-off event, on March 24 at Winghaven Park from 10:00-11:30, the group will be loaning out ivy-removal tools, giving away free native plants, demonstrating how to remove ivy, teaching what ivy does to forests, and even holding a drawing for one lucky person to win 3 hours of ivy removal by a professional crew on their own property. The event is free and open to the public. Come dressed to try your hand at removing ivy. There’s plenty for everyone to practice at this site. For directions and more information see the event poster at http://tinyurl.com/ivyoffvashon. Free Evening Workshop in Bellevue on Invasive and Noxious WeedsGet a jump on the weeds this year. We will be holding an evening workshop on April 5, 6:30 pm-8:30 pm, at Mercer Slough Environmental Education Center. The class will cover identification and control of our area’s tough invasive plants and noxious weeds, especially those found in urban and suburban greenspaces and backyards. Find out what plants to watch for and how to control them effectively and safely. Make sure you can identify poisonous weeds like hogweed, poison-hemlock and bittersweet nightshade. Get the latest best management techniques for English ivy, knotweed, bindweed and other tough plants. This class will feature live plant specimens, a slide show, and lots of resources on weed control methods and identification. Register through the City of Bellevue Parks website at MyParksAndRecreation.com (Class title and number is Noxious Weeds and Invasive Plants - 64219) or contact us for more information. WSDA license recertification credits have been requested (2 credits).. New Research on English Holly Reveals Interesting TrendsAn exciting new research project is being conducted out of the University of Washington-Bothell on the spread of English holly in the forests of Saint Edward State Park. Dr. David Stokes will describe the study’s goals and present the preliminary findings and plans for future research at a special seminar on Thursday, April 26, 2012, 2:30-3:30pm, at King Street Center, 201 S. Jackson St., 6th Floor Conference Room, in Seattle, Washington. This study is examining the distribution and spread over time of English holly in a Pacific Northwest forest ecosystem. Saint Edward State Park is unusual in our area because it contains a significant area of largely intact native Puget Sound forest with a relatively diverse native plant community and mixed age forest canopy, even approaching a mature forest in some sections. It also has very high public use and is adjacent to large areas of urban development, and so has a high value both as a public amenity and for habitat to Puget Sound flora and fauna. By mapping the vegetation and sampling the ages of the trees, this study is able to show the changes over time of the distribution of English holly on the site. Although the data is preliminary, it shows some very interesting trends. For instance, the researchers see evidence that the rate of spread of English holly in the park is increasing exponentially and has sped up significantly in recent years. According to the study’s preliminary research report, it appears that English holly “has the potential to become a dominant species both in number of individuals and area covered within a few decades”. Dr. Stokes has developed a research agenda that could be highly useful as a guide for the management of English holly in our forests as well as for understanding how its distribution is likely to change over time in similar forests and what impacts it will have on the existing plant community. For more information on the April 25 presentation, or for directions, you can contact us at 206-296-0290 or noxious.weeds@kingcounty.gov. Sign up Now for Professional Noxious Weed Recertification SeminarsWe are taking registrations for our annual noxious weed workshops for vegetation management personnel, landscapers, and others working on noxious weed control. Session dates are May 2 and May 9, with a third session on May 23 open primarily to King County staff (and others if space is available). The agenda will be the same for all three sessions and will include a variety of topics related to noxious weed identification and control as well as the ever popular live weed specimens (seeing weeds in person is the best way to learn to identify them). More information is available on our website. All sessions are free and open to the public but space is limited so pre-registration is required. WSDA pesticide license recertification credits have been requested (4 credits). Register online on our website. For more information, contact us at 206-296-0290 or by email at noxious.weeds@kingcounty.gov. Where to Find our Weed Info Booth this SpringYou will be able to ask weed questions in person, check out live weed specimens, and pick up fact sheets and booklets at the following locations in March, April and May (check out our complete schedule online and if you have a community event that could use a booth on invasive and noxious weeds, please contact us): - March 17, Lake Forest Park Earth Smart Green Fair, 10am-2pm, Third Place Commons, Lake Forest Park
- April 21, Shoreline's Natural Yard Care Fair, 9am-3pm, Central Market, Shoreline
- April 21, Earth Day in Newcastle, 10am-4pm, Lake Boren Park, Newcastle
- May 12, WNPS Native Plant Sale, 10am-4pm, Bellevue Botanical Garden, Bellevue
- May 12, Tukwila's 10th Annual Backyard Wildlife Festival, 9am-3pm, Tukwila Community Center, 12424 42nd Avenue South
Ecology Awards Grant to Control Aquatic Weeds on Lake DesireKing County Weed Specialist Ben Peterson has received a grant from the Washington Department of Ecology's Aquatic Weed Management Fund to implement the Lake Desire Integrated Aquatic Vegetation Management Plan. Ben wrote the plan in 2011 with the help of Lake Desire residents. Lake Desire, located southeast of Renton in unincorporated King County, has a pioneering Eurasian watermilfoil infestation, a growing problem with fragrant water lily, and one of the worst purple loosestrife infestations in the county. Ben will be working with residents, volunteers and contractors to control these noxious weeds using an IPM strategy. The project is funded for $35,000 and will run for three years, from 2012 to 2015. Noxious Weed Job Openings in Snohomish CountySnohomish County Public Works is looking for 3-4 full-time, seasonal noxious weed technicians. The closing date is March 22, 2012. More information and the application are on the Snohomish County jobs website. The positions are expected to work through the end of October, 2012. In addition to controlling noxious weeds, the technicians notify and work with landowners about noxious weeds, and provide outreach and education. New Aquatic Noxious Weed Control NPDES General Permit Issued The Washington Department of Ecology has issued a new Aquatic Noxious Weed Control NPDES permit, effective as of February 17, 2012. As with previous permits, this one has been issued to the Washington Department of Agriculture, and licensed pesticide applicators can apply for “limited agent status” under this permit at no cost (go to http://www.ecy.wa.gov/programs/wq/pesticides/apply_online.html). There are two main changes to the new permit. First, it now only covers herbicide application to emergent weeds or weeds near water where herbicide may indirectly enter the water, whereas previously this permit also covered application directly to water in rivers and streams. This change also simplifies the notification and posting requirements, which is a plus. The second major change is the addition of five new chemicals to the approved aquatic herbicide list, more than doubling the number of chemical tools available for emergent weed control. In addition to the previously approved chemicals 2,4D, glyphosate, imazapyr and triclopyr TEA, the permit adds the following: - Bispyribac-sodium (e.g. Tradewind ™) – broad spectrum systemic herbicide
- Carfentrazone-ethyl (e.g. Stingray ™) – contact herbicide
- Flumioxazin (e.g. Clipper ™) – contact herbicide
- Imazamox (e.g. Clearcast ®) – broad spectrum systemic herbicide
- Penoxulam (e.g. Galleon SC ™) – broad spectrum systemic herbicide
The Aquatic Plants and Algae Permit, which is required for application of herbicides directly to water (for floating and submerged weeds), is also being updated to include these five new aquatic herbicides. The efficacy of the new chemicals against our common emergent noxious weeds isn't well known yet, but it's nice to have a few more tools available. For more information or to read the final noxious weed control permit, check out the Ecology website: http://www.ecy.wa.gov/programs/wq/pesticides/final_pesticide_permits/noxious/noxious_index.html. Better Use of Integrated Weed Management Encouraged to Offset Increase in Herbicide-Resistant WeedsRecently, there has been a fair amount of media coverage on one of the down-sides of the widespread use of glyphosate-based herbicides such as Roundup, especially in farms using Roundup-ready crops: weeds that are becoming resistant to this popular herbicide. It comes as no surprise to those of us in the weed control field that the abundant and repeated use of a single herbicide over the same fields is producing an unprecedented increase in weeds that are able to resist that herbicide. This is just basic population biology. If you expose a plant population to a severe stress like an herbicide, only the resistant individuals will survive to reproduce. Over time, the survivors will multiply and thrive without any competition from the other forms of the weed that are being killed by the stress. The problem is even worse if the herbicide is applied over a large area such as a crop field, as opposed to being spot sprayed on only a few areas. The use of crops that have been bred to tolerate Roundup or other herbicides is very tempting to farmers since it greatly simplifies weed control – just plant your crop and spray the field with the herbicide as often as needed to kill all the weeds. Unfortunately, over time, this technique is more likely to result in resistant weeds than using a combination of methods. Recent news stories have covered this problem and are showing once again that Integrated Weed Management is the safest and most sustainable approach to weed management in crops. Integrated Weed Management encourages the farmer to adapt and change their tools to keep up with the evolving weed situation. It’s not a new or particularly complicated approach, but it does take more planning and sometimes costs more money, at least in the short term. However, in the long term, sensible and integrated approaches will keep farms productive and reduce weed resistance. Two recent stories on this topic are: Puget Sound is in Trouble: Find out Why, What King County is doing about it, and What You Can Do to HelpStormwater, or polluted runoff, is the leading contributor to reduced water quality in Puget Sound, and a significant pollution source of our nation's waters. As part of an ongoing commitment to protect public health and improve environmental conditions in our streams, rivers, lakes and Puget Sound, King County annually reviews and updates its overall stormwater management plan. The plan details the efforts of the County to comply with its Clean Water Act stormwater discharge permit. King County is interested in getting feedback from county residents on its development and implementation. You can provide input by taking the online stormwater survey or send comments via email to stormwater@kingcounty.gov or through the U.S. mail by to the Stormwater Management Team, King County Department of Natural Resources and Parks, 201 S. Jackson St., Suite 600, Seattle, WA 98104. Public comment on the program will be accepted through March 9. If you would like to learn more about this topic, the county has developed some great videos that teach about polluted runoff, its impacts on the environment, how the county is addressing the issue, and how we can help minimize impacts on our local waters. To see the videos, visit the Stormwater Video Library. For more information about stormwater, please visit: Presentations on the Stormwater Management Program to interested groups can be requested by emailing stormwater@kingcounty.gov. NOTE: To receive KC Weed News by email, contact Sasha Shaw.
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