KC Weed News - November 2008

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Weed of the Month: English Ivy and Atlantic or Irish Ivy (Hedera helix, H. hibernica), Class C Noxious Weeds in King County, Washington

Have you ever wondered what ivy flowers look like or whether this plant even flowers? If you look closely this month you might notice the subtle floral display on English ivy. On the way to my daughter’s school we walk past one very dense patch of ivy. The past few weeks we have watched the ivy’s small flowers appear like little green aliens rising above the mass of glossy leaves. In spite of my bad opinion of this plant, I have to admit the flowers are kind of interesting to look at, somewhat sweet-smelling and they attract lots of bees. Flowers only grow on mature stems of ivy that can be identified by shiny, unlobed leaves instead of the usual dull, dark green lobed leaves of the non-flowering ivy stems. I found a great close up photo of these flowers at Vanderbilt University’s bioimages website. Also, it shouldn’t be hard to find a patch flowering this time of year for you to observe these little flowers in person. Although flowering ivy branches are most abundant along the upper branches of trees or up fences and buildings, they can grow anywhere that gets enough sun.

The purple-black berries that follow ivy’s flowers are bitter and poisonous to us (see the Vanderbilt website for a fruit photo closeup. However, they are eaten by English house sparrows, European starlings, robins, cedar waxwings and other birds. Ivy berries mature early in the spring when other berries are scarce and birds spread English ivy into both natural and urban forests where ivy seedlings easily germinate in a wide range of conditions from sunny to shady and moist to dry.

In the not-so-distant past, English ivy was often recommended as a lawn substitute and shade-tolerant groundcover because it will survive almost anything and spreads easily on its own. More recently, there has been a growing awareness of the harm caused by English ivy. Parks gardeners and urban foresters may have been the first to notice the damage but the awareness has spread far and wide and there has been both official and unofficial recognition that this plant is a problem. English ivy is a listed noxious weed in Washington and Oregon, many land managers are now working voluntarily to remove this plant, and more and more professional landscapers have stopped installing it in new plantings. Although it is still legal to sell English ivy in Washington, some nurseries have chosen to remove the invasive ivy species and cultivars from their stores and others would probably do so if more customers expressed their concerns about this plant. A document by The Nature Conservancy sums up the costs of ignoring the spread of English ivy:

In the end, the results of societal passivity regarding ivy will be extensive loss of shade trees, declines in native flora and fauna, water quality and forest productivity; and increases in erosion, slope failures and landscaping / management costs for private citizens, the forest industry and public agencies alike. (http://tncinvasives.ucdavis.edu/moredocs/hedhel02.pdf)

More and more cities and community forest restoration projects are beginning to take on ivy removal in urban parks and greenspaces and it is likely that there is an effort in your neighborhood that would welcome assistance. Volunteers are hard at work (and more are needed) in projects throughout the county including Preston, Seattle, Kirkland, Shoreline, Mercer Island, Burien, Des Moines, Normandy Park, Issaquah, Renton, Bellevue, Lake Forest Park, and Federal Way to name a few. There are probably even more projects out there than I am aware of. If I’ve left one off that you know about, please let me know. The Washington Native Plant Society manages the Ivy OUT website www.IvyOUT.org and they list numerous contacts for ivy pulls in our area at http://ivyout.org/volunteer.htm. More contacts for volunteer events can be found on our volunteer info page.

Weed Tips for November and December

Pulling weeds is just the thing after big holiday meals. Getting outside this time of year can be especially refreshing and weed pulling will keep you warm in the chilliest of weather. In late fall and even in winter, our soil doesn’t really freeze around here. So, unless the weeds are under water, most are still perfectly pullable this time of year. A lot of plants have died back and trees and bushes have lost their leaves, making it a good time to find weeds you might not usually notice or be able to get to easily. In my yard this includes herb Robert, creeping buttercup and creeping wood sorrel (Oxalis corniculata) in the garden beds and blackberry, ivy and holly all around my fence where they sneak in from the neighbor’s yards. Except in low areas, the soil is pretty loose and roots pull out nicely without breaking off. Also, if you disturb the roots of your plants a bit, it won’t hurt much this time of year since they are mostly dormant.

Winter is a great time to study up and plan for next year. While you still remember what happened this year with weeds on your property, take this time to write out what weeds you will have to deal with next year. Hint: it will be pretty much everything you had this year and possibly the weeds your neighbors let go to seed also. Do you need to find some new strategies to deal with these weeds? If something went to seed before you could get to it, that’s a good sign that you need to do some planning. What can you do to improve the areas where the weeds were the worst? Bundle up and take a walk around your property with a notepad to jot down ideas for different areas and questions you need to answer about the weeds. This might be the time to check out our website for brochures and Best Management Practices on some of your weeds. Or you could phone or email someone at our office or WSU Extension for some tips.

Get a soil test to see if fertility or pH need some adjusting. Often, weeds are a sign that something is not right with the garden, yard or pasture. If the plants you are trying to grow are not getting what they need, they won’t compete as well with weeds. No matter how often you control weeds, if there are holes and weak plants, you will keep getting more weeds. Soil tests can be done anytime and then you can research how to fix any problems the test reveals. The King Conservation District provides a soil testing program for King County residents or contact Marcie Hagan at 425-277-5581 ext 106.

On your brisk fall walks, look for overwintering noxious weeds along trails and woodlands. If you find regulated noxious weeds like tansy ragwort, garlic mustard or milk thistle, please contact the noxious weed program or the property owner right away. There is a lot of control that can be done in the winter and it’s always better to know sooner than later if something has to be done next year. Other, non-regulated noxious weeds that are also visible this time of year include poison hemlock, yellow archangel, herb Robert and bull thistle.

Scotch broom is a great winter project. Not only is it very easy to find with its evergreen stems, it is easier to pull in moist soil and you are less likely to damage roots of nearby plants. Unlike blackberries, Scotch broom doesn’t have thorns and so makes for an easy work party activity if you can get a few weed wrenches for people to use. Often parks departments have weed wrenches available for work parties on public lands. If you need a weed wrench for your own property, you can borrow ours for a week or two. Just contact us at 206-296-0290 to reserve a time and then come to our office in Seattle at 2^nd and Jackson (next to the train station) to pick it up.

Collect holly berry branches to decorate for the holidays and stop it from spreading. Sadly enough, our old holiday favorite English holly is also causing considerable trouble in the woods as it spreads in our urban woodlands and national and state forest lands. If you have the urge to decorate this winter, by all means take cuttings of holly laden with berries inside where they can bring holiday cheer. This will also provide the benefit of preventing birds from carrying the seeds off to invade any new forests. Holly invasion is especially a problem in the more remote areas of the county. Once holly gets into a forest, it often goes undetected for a long time and can get well-established before anyone notices it. Around the Middle Fork Snoqualmie Valley near Mt. Si, English holly is making serious inroads into the forests, spreading from a former holly farm, and causing anything but holiday cheer for those of us who are hoping to restore and protect this gem of a natural area in our county. For information on holly control, check out our new fact sheet on English holly posted on our brochures page.

Blackberry Added to Washington’s Noxious Weed List

It’s time again for the annual updates and revisions to the Washington State Noxious Weed List. The annual public hearing is done and the state weed board has decided on the changes to next year’s weed list. What impact does this have on you? It depends on where you are in the state and what you are trying to do, but for King County property owners the biggest change may be the status of our two invasive European blackberry species. It is no surprise to any of us that Himalayan and evergreen blackberry are invasive, difficult to control, and taking over vast areas of land in the region. What may be a surprise is that neither species was an official noxious weed in this state. That changes in 2009. Both invasive blackberry species have been added as Class C noxious weeds to Washington’s weed list. This means that county weed boards have the option to require control of blackberry for all or parts of their county, although that is not likely to happen considering how widespread it is! It also means that when we educate people about noxious weeds, we can include blackberry on that list, and that rules and regulations that allow exceptions for noxious weed control will now apply to invasive blackberry species along with other noxious weeds. Considering that these two species likely cover more area than any other invasive plant in western Washington, it is probably high time that they were included on Washington’s noxious weed list.

Other changes to the state noxious weed list include the upgrade of the Class B weed smooth cordgrass (Spartina alterniflora) to the Class A list (good news since this shows how successful the state has been in reducing this weed to the point where eradication could be possible) and three new Class A noxious weeds (bad news since these are all imminent and growing threats to natural areas in the Pacific Northwest). The new Class A weeds are:

Shiny geranium (Geranium lucidum): A rapidly spreading cousin of herb Robert (a.k.a. stinky bob). It looks something like the weedy geranium called dove’s foot but has shiny leaves and reddish stems. It spreads in large, dense infestations in woodlands and forest clearings somewhat like herb Robert, but possibly more limited by shade. Currently spreading badly in a few places in Oregon (see the Western Invasives Network website), it appears to be limited to only a few locations in Washington – one in Bayview State Park and nearby Padilla Bay in Skagit County and a couple of places in Skamania and Clark Counties. Given its ability to spread by seed, this plant is likely to start showing up in more places and new sites should be reported immediately to the noxious weed program.

False brome (Brachypodium sylvaticum): This grass is invading in woodlands in Oregon’s Willamette Valley and is potentially a significant threat to Washington’s woodlands. Although it can be difficult to distinguish different grass species, this one is shade tolerant and remains green throughout the late summer and fall when most grasses turn brown. A perennial grass, it forms short bunches, has broad, flat, lax leaves and a leaf sheath that is open all the way to the base. The leaf margins and lower stems have long, soft hairs, the flower spikes droop, and the spikelets have short or no stalks. Native bromes have sheaths that are mostly closed and flowers in open, branched panicles and spikelets with stalks. If this is all Greek to you, don’t worry too much. We will be looking hard for this grass in King County, but so far it is limited to Oregon and one spot in southern Washington (Skamania County). For more information, see the Oregon Department of Agriculture web page on false brome.

Flowering-rush (Butomus umbellatus): This aquatic plant is often first introduced to lakes because of its lovely flowers but quickly spreads to become a huge nuisance and a threat to aquatic ecosystems. It occurs throughout much of the northern United States from Vermont to Idaho and in much of southern Canada. In Washington, it is so far known to occur only in Silver Lake in Whatcom County, where it is very abundant and interferes with swimming, boating, and fishing and increases the occurrence of swimmer’s itch by hosting the snail used by this particularly annoying pest. It is likely to show up in other lakes and wetlands in Washington although it tends to move slowly between infestations, spreading mostly vegetatively. Any sightings of this species should be reported immediately to the noxious weed program. Photos can be found at the Center for Aquatic and Invasive Plants website and more detailed information can be found at the Invasive Plants of Natural Habitats in Canada website.

For more information on these and other changes to the state noxious weed list, see the Washington State Noxious Weed Board website.

Mid Fork Snoqualmie Valley Weed Watcher Report

This summer and fall, eleven volunteers went hiking with a purpose – to find and stop invasive plants before they spread into the upper watershed of the Middle Fork Snoqualmie. Together they surveyed about 25 miles, covering about eight different trails. This effort came about mostly because of the vision of one very dedicated volunteer, Mark Boyar, who has been working tirelessly to protect and restore this beautiful valley in the foothills of the Cascades. Mark is the mastermind and the motivation behind a cooperative weed management effort called the Middle Fork Snoqualmie Invasive Weed Project. This effort brings together the resources of the Mountains to Sound Greenway Trust, the Mt Baker Snoqualmie National Forest, Washington Department of Natural Resources, the King County Noxious Weed Program, and the Cascade Land Conservancy. The partners are all engaged in finding and removing invasive species in the Mid Fork Valley. However, there aren’t enough staff or resources to survey the trails and old roads, which are the pathways from the more infested lower elevation areas up to the wilderness and more pristine upper watershed.

To solve this problem, Mark brought together the botanist from the Mt. Baker Snoqualmie National Forest and the staff of the King County Noxious Weed Program and asked us to develop a Weed Watcher program for the trails of the Middle Fork Snoqualmie Valley. After trying a few different approaches, we developed some pretty straightforward survey forms and procedures that seem to work for everyone. So, early this summer, we provided a day of training and practice surveying, had everyone pick trails, handed out forms, and left the rest to the volunteers. Over this summer and fall, the weed watcher volunteers set out on in twos and threes to hike and survey the trails they had selected.

We had several people participating who just liked to hike the Mid Fork trails and we were also fortunate to have several plant enthusiasts participating from the Washington Native Plant Society. The trails surveyed included: the CCC Trail, Granite Lake, CCC Connector, Taylor River, Marten Lake Spur, Middle Fork Trail, and Hester Lake Trail. The information they collected was passed on to the folks at the Mountains to Sound Greenway Trust who have crews and work parties throughout the season to remove invasives in the watershed. Also, several Weed Watchers took on the task of simply pulling the weeds they found – an excellent idea since the earlier these plants are removed, the less they will continue to spread. If possible, the ideal would be for volunteers to adopt their trails and remove small patches of invasives as they are surveying. Although this work may seem like a small part of the overall need, none of this survey and control work would have been done if it were not for the volunteers. It is invaluable to have this help from volunteers for work that simply wouldn't happen any other way.

This project is an excellent example of Early Detection and Rapid Response. Most of the trails surveyed had very few invasive species and this effort will allow us to nip them in the bud before they spread any further. It is almost impossible to remove invasives from wilderness areas once plants get established. This trail Weed Watcher program should allow us to stop the invasives early enough to keep that from happening. Next year we plan to continue with this project and expand to other trails as well. If you are interested in hiking with a purpose and helping us find invasives while there is still time to remove them and to protect our wilderness and recreational areas, please contact me at sasha.shaw@kingcounty.gov or Mark Boyar at mboyar@practicepartner.com.

Snoqualmie River Garden Loosestrife Update

This was the second year of our effort to eradicate garden loosestrife (Lysimachia vulgaris) from the Snoqualmie and the Raging Rivers in King County, funded in part by a grant from the Washington State Department of Ecology. We knew this plant would be challenging to eliminate due to its extensive roots and the seed bank. Also, these rivers present even more of a challenge due to extensive flooding and strong currents – we just never know where the garden loosestrife will be moved any given year. The garden loosestrife populations are small and scattered, which is good for the habitat, but bad for locating it in order to control it. What this means is a slow, careful survey along each shore, controlling any populations as we find them. Although this effort is as challenging as we expected, we are making good progress.

This year, the noxious weed program contracted with Aquatechnex to find and treat the garden loosestrife growing on the Snoqualmie River and took care of the Raging River populations with in-house staff. To get a sense of the scale of the problem, it helps to look at some numbers. On the Snoqualmie River, we found and treated 132 separate patches of garden loosestrife from the Raging River downstream to the county line. On the Raging River, we found and controlled 15 patches of garden loosestrife in the lower 2 miles of the river. On both rivers, almost all of the patches were right along the shoreline and 22 of the Snoqualmie River patches were actually out on sand bars in the river. Most of the patches were fairly small, many just single plants, but there were a few large infestations. The largest on the Snoqualmie River was 8,000 square feet and the largest on the Raging River was 900 square feet. What this means is that most of the time was spent finding the patches and much less time was spent controlling them.

We are able to do this project in large part due to the cooperation of the property owners along both rivers – 35 private landowners and 4 public agencies had garden loosestrife infestations. We contacted all property owners on the rivers and gave them the option to opt out of this project and control the loosestrife on their own. However, no one who had garden loosestrife on their property opted out and we were able to treat all the populations we found along both rivers. This comprehensive approach to controlling the garden loosestrife is really the only way to achieve eradication, since plants move around so much in these river systems. Most of the sprayed plants were very effectively controlled. We also found that many of the existing patches sprayed in 2007 did not flower in 2008, so we are making good progress toward working away at the seed bank as well as the current populations. Our goal is eradication of this damaging invasive species from the rivers, so we will continue to work away at it and expect to see less and less each year. If you have any questions about this project or other aquatic weed issues, please contact our Aquatic Weed Specialist Katie Messick at 206-296-0290 or katie.messick@kingcounty.gov.

Oregon Bans Sale of Butterfly Bush Cultivars

Starting in 2009, Oregon nurseries won’t be able to propagate or sell named cultivars of butterfly bush (Buddleia davidii), according to a recent news article in the Oregonian. Starting in 2004, the Oregon Department of Agriculture had already banned the sale of the species Buddleia davidii, but had excluded all the named cultivars. They added the cultivars after seeing the results of research on the invasiveness of the cultivars in Oregon by James Altland, assistant professor of horticulture and nursery crop extension agent for Oregon State University, and student Julie Ream. As suspected, all of the cultivars contribute to the spread of this plant. In Oregon, property owners are allowed to keep existing plants of butterfly bush but will need to remove seed heads in the fall to prevent spread. Also, nurseries have until the end of 2009 to sell existing stock but they aren’t allowed to restock or propagate. According to the article, the ban includes all cultivars including popular varieties such as 'Harlequin,' 'Black Knight,' 'Purple Prince,' 'Nanho Purple' and 'Royal Red.' This rule doesn’t apply to Washington State of course, but it certainly drives home the point that butterfly bush is a serious threat that should not be taken lightly.

Knotweed Biocontrol News from the UK

A recent BBC news article talks about how close scientists are to having biocontrol options for Japanese knotweed in Great Britain (it also has a great video showing how fast knotweed grows!). When researchers went to Japan, they discovered 186 species of plant-eating insects and about 40 species of fungi that attacked Japanese knotweed. When they threw out those that also affected other plants, they were left with two options: a leaf spot fungus and a sap-sucking psyllid insect. The psyllid insects reduce the height of knotweed plants and also result in tiny, curled leaves that don’t bring in the resources like knotweed’s usual large, flat leaves. If these biocontrol agents are approved for release, they would greatly aid in reducing the rate of spread and impact of Japanese knotweed in Britain. For the Pacific Northwest, we may not be so lucky since our dominant knotweed species is actually the hybrid between giant and Japanese knotweed known as Bohemian knotweed, but the psyllid and a few other insect species are being researched here as well to see what will work. University of Washington researcher Fritzi Grevstad at the Olympic Natural Resources Center is the lead researcher and several insects are being investigated in Corvallis at Oregon State University. The key will be to find organisms that will attack all the invasive knotweed species we have here in the Pacific Northwest but stay away from all of the closely-related natives and other beneficial plants.

More Weed News

Lake Sammamish property owners are battling invasive weeds

Weed Control Kauai-Style: Nature Conservancy Uses High-Tech Plane to Eliminate Invasive Weeds

Montana’s Weed-Eating Sheep make the New York Times: Got Weeds? These Sheep Will Make House Calls

Beware of Weeds in Bird Seed (and useful tips to prevent problems) – two news articles covered this story: Christian Science Monitor and the Post-Bulletin

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