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Search Results for ' Noxious weeds--Washington'

PAL Questions: 10 - Garden Tools: - Recommended Websites: 2

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Keywords: Hedera hibernica, Hedera helix, Invasive plants--Control, Noxious weeds--Washington

PAL Question:

I am trying to write a letter about English ivy in order to get it removed from a public library. Is it a noxious weed?

View Answer:

Washington State and King County noxious weed information is updated annually. Currently, three cultivars of Hedera helix and one cultivar of Hedera hibernica are Class C Noxious Weeds in the State of Washington.

Here is the link to descriptions of these four types of English ivy.

Class C Noxious Weeds are weeds that are already widespread; removal is NOT required by law. However, individual counties can adopt removal programs as they see fit. Here is the complete list of Class C noxious weeds in Washington.

King County also has more information on a website about noxious weeds.

King County does not require control or eradication of any of the four English ivy cultivars. Although control is strongly recommended, it is not required.

Season All Season
Date 2008-01-10
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Keywords: Genista, Spartium junceum, Cytisus, Noxious weeds--Washington, Allergies

PAL Question:

My question is about Cytisus. People with allergies complain about the Scotch broom that grows wild. Are the other tame varieties like C. x praecox going to be a pollen allergy problem also? I want to plant it as an informal hedge and my customers are worried. I want to tell them there is no comparison in the plants. Am I right?

View Answer:

To answer your second question first, Scotch broom (Cytisus scoparius) is an invasive European species that has given all brooms a bad name. Spanish broom (Spartium junceum) is also invasive, and is considered a Class A noxious weed in Washington State. There are garden-worthy brooms such as C. x praecox. A staff member here grew one in her previous garden for many years (and loved it). Some species of Genista, such as Genista stenopetala, are reportedly not invasive.

According to the book Allergy-Free Gardening by Thomas Leo Ogren (Ten Speed Press, 2000), Cytisus ranks 5 on the allergy index scale of 1 to 10, but allergy to this plant is uncommon, except in areas where there is a lot of it growing. Spartium junceum rates a 7, while Genista rates a 4, about the same as a begonia or a primrose.

Season All Season
Date 2006-12-08
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Keywords: Kochia scoparia, Spartium junceum, Cytisus, Flower arrangement, Noxious weeds--Washington, Corylus

PAL Question:

While living in Japan and practicing flower arrangement, I often used a branch known as ossified broom. It was always available at flower stores there. The color is gray-green, has the typical multiple straight stems as Scotch Broom but also had some thick and twisted branches that are very attractive in arrangements. I would like to plant it so that I would have a ready supply. Can you help me find the correct name?

View Answer:

I consulted a number of books on Japanese flower arrangement, including The Art of Arranging Flowers: A Complete Guide to Japanese Ikebana, by Shozo Sato (Harry N. Abrams, 1965). 'Broom' may be the common name of a number of different plants, such as Spanish broom (Spartium junceum), Scotch broom (Cytisus scoparius), and broom cypress (Kochia scoparia). Unfortunately, these plants are considered noxious weeds in the State of Washington.

You may want to consider a type of broom (Genista or Cytisus) that is not considered invasive.

From your description of the branches, I wonder if the appearance would be similar to Corylus avellana 'Contorta' (Henry Lauder's walking stick). Below is a link to information about this plant: www.paghat.com

Season All Season
Date 2006-11-14
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Keywords: Noxious weeds--Washington, Noxious weeds, Invasive plants

PAL Question:

Can you provide me with an extensive list of resources for checking whether a plant is invasive or a noxious weed?

View Answer:

Here is a list of helpful resources:

Washington State Noxious Weed List from the USDA

State noxious weed list and schedule of monetary penalties from the WSL

Class A, Class B, and Class C

Washington Department of Ecology (aquatic plants)

Washington Invasive Species Coalition and their GardenWise handbook

King County Noxious Weed Lists

National Invasive Species Lists

Plant Conservation Alliance Alien Plant Invaders list

Invasives in British Columbia

The lists which are national in scope are useful too, as some plants not yet officially listed as invasive here may still be plants to watch out for.

There are a great many books on this subject. A recent one, co-authored by a faculty member here, is Invasive Species in the Pacific Northwest edited by P.D. Boersma, S.H. Reichard, and A.N. Van Buren; Rebecca L. Gamboa, photo editor. University of Washington Press, c2006.

Season All Season
Date 2007-10-10
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Keywords: Noxious weeds--Washington

PAL Question:

I have three fast-growing hogweed plants in my backyard, but a garden designer at City People's warned me not to tackle them before consulting someone at the Center for Urban Horticulture. She said hogweed is nasty, and it certainly looks so.

View Answer:

If you do have hogweed (Heracleum mantegazzianum), it is a Class A noxious weed (eradication required by law in King County and the State of Washington). You should contact the King County Noxious Weed Control Program to report it using their Infestations Form.

The folks at City People's were right to tell you not to touch it, as the sap is considered a public health hazard. Any skin exposed to it will become extremely sensitive to sunlight. King County provides more information about the effects.

You can find out more about the history of this invasive in North America (including a song!) at the site E-Flora B.C.

Season All Season
Date 2008-06-04
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Keywords: Noxious weeds--Washington

PAL Question:

I bought a plant at a local plant sale, Salvia sclarea 'Turkestanica'. As I was researching the plant online, I saw several nurseries stating that the plant can't be sold in Washington State. Am I right in thinking that this is an invasive species? Is it safe to plant in Seattle?

View Answer:

You are correct about its invasive potential. Clary sage (Salvia sclarea) is a Class A noxious weed and cannot be legally sold in Washington, since at least 2003. Eradication of Class A weeds is mandatory. I imagine that the seller was unaware of its status in Washington. Here is more information from the King County Noxious Weed Control Board.
According to the USDA's Germplasm Resources Information Network, Salvia sclarea 'Turkestanica' (or turkestaniana, as it is spelled here) is a synonym for Salvia sclarea, so it would not be exempt from the weed regulations.

Season All Season
Date 2008-09-17
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Keywords: Clematis vitalba, Noxious weeds--Washington

PAL Question:

I would like to know about controlling Clematis vitalba which is invading my garden from next door.

View Answer:

Clematis vitalba, also known as Traveler's Joy or Old Man's Beard, may be a challenge to control without some cooperation from your neighbor. If your neighbor will agree to keep it from going to seed, that will help a little. You might also persuade the neighbor to eradicate the plant, which is a Class C Noxious Weed in Washington State (and in King County), meaning that it is widespread, and enforcement of control is optional but recommended. It is listed in the GardenWise booklet (copies available in the Miller Library and in some local nurseries) which describes noxious weeds and alternative plantings.

The Northwest-based website of Rainyside Gardeners has useful directions on getting rid of this vine. Here is an excerpt:
"The first step in the removal of traveler's joy requires cutting the plant's stems above the ground. It is important to make sure the space between the two pieces is large enough to prevent the stem from reattaching itself to the root. Stems can reroot if left in contact with the ground for a long period of time, so periodically move any portions of the plant left in situ. Do not tug on the stems still in the trees. Gravity never sleeps! Pulling on the stem might bring down more than you can handle (all the stem, host branches, or possibly the entire tree).
Digging out the roots of the traveler's joy is surprisingly easy, but these roots may extend for a long way. Often the roots will be a tangle of overlapping coils and may even come from a distant plant. After that task has been accomplished, a gardener will need to be on the look out for the seedlings that may pop up.
Traveler's joy is an insidious pest because it readily reproduces vegetatively and by wind cast seeds. The vine-like growth habit spreads myriad possibilities of reproduction over a large area. If a neighbor has an untended C. vitalba, a gardener may find themselves cleaning up their neighbor's mess.
Because the roots run shallow, simple 'pull and pile' is the best method to kill C. vitalba. Some sources suggest bagging all removed sections of the plant, for an off-site disposal, or burning on-site. Burning adds to the air pollution and may attract unwanted attention from authorities who carry weapons. Therefore, burning should be avoided. Simply moving the pile periodically, or placing the debris on an impervious surface until it has died and begins to decompose, may be all that is needed."

Season All Season
Date 2008-10-29
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Keywords: Cytisus scoparius, Noxious weeds--Washington, Plant quarantine, Invasive plants

PAL Question:

Is it safe to plant Cytisus scoparius 'Moonlight' here on Whidbey Island? I know that Scotch broom is thought to be invasive, but I wonder if maybe this variety is less of a problem.

View Answer:

Some sources (such as the State of Oregon's noxious weed control board) have said that "sterile cultivars" of Cytisus scoparius are exempt from regulations governing noxious weeds. However, the Center for Urban Horticulture's Professor Sarah Reichard, an expert on invasive species, says the following:

"The 'sterile cultivar' issue is huge worldwide. The reality is that sterile cultivars depend on the type of sterility: there are many reasons a plant might be sterile. Only a few of them can be considered to be stable under varying environmental conditions.

Regardless of what is done in Oregon, in Washington it is illegal to sell or grow any cultivars of Cytisus scoparius. Moonlight is less aggressive, but I have definitely seen it seeding out. But it does not matter how aggressive it is: it is still on the quarantine list in this state because that is the way the state law is worded. Island County may not have it on their high profile noxious weed list because it is only a B non-designate there because it is widespread. But our noxious weed (control) and our quarantine lists are two different things in this state and it is quarantined here."

For future reference, here are links to Washington State Plant Quarantine and Noxious Weed lists.

Season All Season
Date 2009-05-16
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Keywords: caterpillars, Senecio jacobaea, Biological control, Noxious weeds--Washington, Weed control--Pacific Northwest

PAL Question:

I was just walking through a wild area in Seattle with lots of weeds, and came across some strange caterpillars. They are mostly hairless (to the naked eye, anyway), and are striped black over orange with black legs. Can you tell me what they are?

View Answer:

I believe you may have seen the Cinnabar moth caterpillar, Tyria jacobaeae, which was introduced to the United States to control a noxious weed, tansy ragwort (Senecio jacobaea). Here are pictures to compare, and more information:
Wikipedia
Flickr image
Gerald Durrell Jersey Zoo

Both Washington State's noxious weed control board and King County Noxious Weeds have information on weed control with Cinnabar caterpillars. (See page 5 of the document). Tansy ragwort is a Class B noxious weed, and control is required in King County.

Season All Season
Date 2009-07-16
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Keywords: Silybum marianum, Noxious weeds--Washington

PAL Question:

Silybum marianum: Should I give away baby plants? I bought the original "rare" plant from a local Perennial Society (can't remember exact name)15 years ago. 4 feet tall, and prickly. I decided to get rid of it, but baby plants still pop up every year. Variegated, dramatic, but too prickly for small garden!

View Answer:

I'm glad you asked about your Silybum marianum starts. This plant is considered an invasive species in many places, including Washington State. King County lists it as a Class A noxious weed, meaning that eradication of the plant is required by law. Below is information excerpted from King County's site:

This Class A noxious weed has a very limited distribution in Washington State, and eradication is required. The largest infestations in the state are in pastures in the southeastern section of King County but infestations are occasionally found elsewhere. Early detection and rapid, effective response is of the highest priority for this noxious weed.

Although occasionally found in gardens, it is illegal to sell or buy milk thistle in Washington State and all existing plantings should be removed in order to prevent accidental spread.

Milk thistle is toxic to livestock when consumed in large quantities, and it forms dense stands in pastures and rangelands. California reports up to 4 tons per acre in heavily infested areas. The leaves are very distinctive, with white marbling on the shiny green leaves.
Control Methods:
Manual: For small sites with few plants, pull or dig up rosettes or the bolted plants before seed heads form. Use a shovel to cut the plant off about one inch below the ground so the plant will not re-sprout. Chopping the leaves from one side of a rosette can provide access to the central growing point. Wear protective clothing. To be fully effective, all mature seed heads need to be bagged and removed so no new seeds are left on the site. Immature seeds can continue to develop in cut plants, and the less stem that remains attached to the flower head, the faster the seed head will dry out.

I highly recommend you do what you can to eradicate this plant and prevent its spread. Do not put it into the compost but instead bag and dispose of it as trash.

Season All Season
Date 2011-06-10
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June 24 2013 12:55:25