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The Noxious Nine

Some weeds are worse than others. Below is a list of the most noxious weeds that have found a home on Bainbridge Island. Please help control these weeds. Vow to yank out one of the Noxious Nine every time you take a walk; if we all pull together, we will win!

Tansy ragwort (Senecio jacobaea) Class B Noxious Weed
Poison hemlock (Conium maculatum) Class B Noxious Weed
Spurge laurel (Daphne laureola) Class B Noxious Weed
English laurel (Prunus laurocerasus) Class B Noxious Weed
English holly (llex aquifolium) Class B Noxious Weed
English ivy (Hedera helix) Class C Noxious Weed
Butterfly bush “Baby butterfly killer bush” (buddleia) Class B Noxious Weed
Herb robert “Stinky Bob” (Geranium robertianum) Class B Noxious Weed
Scotch broom (Cytisus scoparius) Class B Noxious Weed
Tansy ragwort (Senecio jacobaea) Class B Noxious Weed

Young plants have basal rosette of ruffled leaves. Mature plants produce leafy flowering stalks, generally 2 to 4 feet tall. The flowers are daisy-like with yellow petals and yellow center. The leaves are dark green on top, whitish-green underneath, with deeply cut,blunt-toothed lobes with a raged, ruffled appearance. Tansy ragwort is often confused with common tansy (Tanacetum vulgare), which has button-like flowers with no petals and flattened, fern-like leaves. Why might these plants be so invasive? The answer is simple; there are up to 150,000 seeds per plant. Seeds can be spread by wind or mowing. Tansy Ragwort is poisonous to cattle, horses, sheep, pets and people; symptoms include swelling, inflammation of membranes, diarrhea, blood in feces, rough coat and excessive fluid in body. Ragwort also displaces quality forage plants due to its highly aggressive growth. Many people will use herbicides to kill these invasive weeds, but the best way to get rid of them is to dig them up eliminating all their roots while being careful not to spread seeds.

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Poison hemlock (Conium maculatum) Class B Noxious Weed

Poison hemlock is a tall green plant with white flowers.  Its purple markings are the best way to identify that it is poisonous. Poison Hemlock invades grazing areas, parks and meadows. Its aggressive growth outcompetes more desirable native species and garden plants. It is found in several places including stream banks, ravines, fields, ditches, unmanaged yards and vacant lots. It prefers moist soil with lots of sun, but it can also grow in drier areas and in semi-shade. For all you philosophy fans out there, the poison tea that Socrates drank was made from this plant. How can it be controlled? For small areas, pull or dig up the plant. Make sure to wear protective clothing including eye protection followed by a thorough washing of the hands. To be fully effective, make sure that the flower heads are not left on the ground. When disposing of the plant, place it in a plastic bag and put the bag in the household trash. Before planting to replace the hemlock, make sure that it doesn't grow back. Once the ground is prepared, plant your replacement of choice and continue to monitor the site for poison hemlock.

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Spurge laurel (Daphne laureola) Class B Noxious Weed

Spurge laurel is an evergreen shrub consisting of shiny leathery leaves and black berries.This shrub is usually found growing in isolated clumps but is capable of forming large, dense monotypic stands in some cases. The flowers are small and inconspicuous light green at the base of the leaves. The black berries that this plant produces are poisonous, one-seeded and oval. This slow growing shade tolerant shrub is spreading through our forests with the help of birds and other rodents. Spurge laurel is often erroneously identified as a rhododendron but it is actually pushing out our beautiful natives by forming large thickets. Once established, these plants are very difficult to eradicate. The best way to eliminate this shrub is to cut the tree at the lowest possible place. To fully control these plants you might need to use herbicide applied directly to a freshly-cut stem, but this should always be the last choice.

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English laurel (Prunus laurocerasus) Class B Noxious Weed

English laurel, also called cherry laurel, is a large evergreen shrub or small tree often used for landscaping, usually as a hedge. Related to cherry trees, English laurel gets itscommon name from its resemblance to the true laurel tree. Native to southwestern Asia and southeastern Europe, this species has been widely introduced in Europe and North America, and has escaped cultivation in many areas, including the Pacific Northwest. English Laurel is a tall, dense, spreading thicket-forming shrub or small tree, 10 to 30 feet tall. It grows as either a single-trunked tree or a multi-stemmed shrub. Evergreen leaves are dark green on top and pale underneath. The leaves are thick, shiny and large with oblong, abruptly pointed tips. The laurel has small white flowers in upright clusters resembling cherry flowers that are cup-shaped with 5 petals and fragrant with many yellow stamens. The plant produces small, purplish-black, cone-shaped, cherry-type fruits, also in clusters. Poisonous parts include wilted leaves, stems, and seeds. The laurel reproduces through seeds, which are distributed by birds and possibly other animals. It also spreads laterally by layering (growing roots from stems where they touch the ground). When cut, English laurel will sucker from the roots and re-sprout from cut stems. The shrub grows in sun or shade, moist or dry soils, but does best in moist, well-drained soils. English laurel was the second most common invasive tree species in a study around Seattle, found on 67% of study plots with an average of 46 stems/acre (English holly was the most common invasive tree found in this study). Impacts of English laurel include out-competing native forest species such as tree seedlings and native shrubs and replacing native canopy trees over time. Laurel is very fast growing and tolerant of disturbance and a wide range of conditions.

English laurel is a strong competitor and thrives in our climate. Because it is spread by birds to remote areas, it has the potential to be a serious threat to native forest land in the Puget Sound region. English laurel is also poisonous. How do you control this plant? Much like the rest of the invasive shrubs or trees, cut stems and trunks by hand or chainsaw making sure to cut as close to the ground as possible.  Then, remove stems to make it easier to control re-growth. Stems can be chipped and used as mulch or taken to a landfill. What would be the best alternative? Native shrubs or trees of your liking similar to the English laurel or a cherry tree!

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English holly (llex aquifolium) Class B Noxious Weed

English Holly is a large, dense, slow-growing evergreen shrub. Holly can reach up to 50 feet tall and 15 feet wide. Holly can grow as a single tree, but is more commonly seen asa multi-stemmed thicket.  Its leaves are thick, glossy and green ranging from 1-3 inches long. On the leaves, you will find sharp spines along the edge. The flowers are small, white and sweetly scented but often hard to spot. Holly produces small red, yellow or orange berries in the winter that are toxic to humans. Reproduction of the plant is mainly caused by the transportation of the seeds. Birds and other wildlife can spread the seeds over a vast amount of land. Holly is a hog when it comes to water, depriving surrounding plants from a sufficient amount of water. What can you do? There is no legal requirement for eradicating or controlling English holly, but there are control methods that are recommended by the Noxious Weed Control Board. Small holly plants can be pulled up when the soil is moist, but larger mature trees have deep extensive roots that make it nearly impossible to pull out. If this is the case, the best option is to obtain a weed wrench which will pry the plant right out of the dirt. A weed wrench can borrowed through BI Parks. If you don't have access to a wrench, cutting the tree at the lowest possible point and monitoring its return usually will do the job as well. Like the look of holly but don't want to put our native plants in jeopardy? Plant Oregon grape instead. This is a native, noninvasive plant that has some of the same qualities and characteristics as English holly.  Another option is variegated holly, which is usually a sterile hybrid http://www.ehow.com/info_7975436_variegated-holly-plants.html

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English ivy (Hedera helix) Class C Noxious Weed

In the juvenile state, its leaves are deeply 3- to 5-lobed, light green and alternately arranged. Stems produce adventitious roots at the nodes and immature plants do not produce flowers. This juvenile stage on average lasts for about 10 years allowing there to be an abundant amount of time to get rid of this invasive plant! In the mature form, leaves are unlobed, or slightly lobed, dark green and leathery and spirally arranged. English ivy matures to produce flowers when it begins to grow vertically.

Weirdly enough, mature plants do not produce adventitious roots. English ivy is an evergreen perennial, which usually grows as a vine although it has been known to grow as a shrub. English ivy has the ability to photosynthesize year-round, and is capable of growth for 9-10 months of the year. This plant is long-lived and has been recorded to grow for as long as 400 years. The entire plant contains toxic compounds and the berries and leaves are poisonous to people and livestock if eaten in large quantities.

So how is ivy destructive to the environment and our humans? Ivy Reaches tree canopies and shades out deciduous foliage during summer months, suppressing the host tree. Dense ivy cover deprives the bark of normal contact with air and microorganisms. Ivy adds substantial weight to a tree. The estimated weight of ivy removed from a tree in the Olympic National Park was 2100 lbs. Mature trees covered with ivy are top-heavy and more likely to be blown down by winds. On top of the harm to the trees, thick ivy mats can accelerate rot and deteriorate structures. The best way to get rid of this ivy is to team up with the community and cut away. Cutting the ivy at the base of the tree will kill all ivy above the cut. If the ivy is in shrub form, make sure to uproot the plant.

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Butterfly bush “Baby butterfly killer bush” (buddleia) Class B Noxious Weed

The butterfly bush consists of flower spikes with arching branches that can reach heights of 15 feet. Young stems are green; mature stems develop scraggly, peeling, gray-brown bark. Leaves are egg-shaped and oppositely arranged, usually between 4-10 inches long and 1-3 inches wide. The flower is a 4-parted bell shape. These flowers are mostcommonly purple with less noticeable orange centers. These flowers are also very fragrant and come into bloom in the mid-summer. The visual appeal and scent is what usually deceives most humans.

The butterfly bush reproduces by producing copious amounts of extremely lightweight, winged seeds that are easily dispersed to distance areas by wind and water. This shrub is a very strong and aggressive invader. The seed can remain in viable for 3-5 years and can also reproduce vegetatively, as cut stems can sprout roots and grow into new plants. Also, this shrub can begin producing seeds during its first year. So what impacts does the butterfly bush cause on the environment? It forms dense thickets, especially along river banks and river gravel bars, which crowd out native vegetation and may alter soil nutrient concentrations. Once established, this shrub is difficult to remove. It will resprout from the rootstock after its stems are cut, and the cut stems can also grow into new plants. While often planted in yards and gardens as an ornamental, butterfly bush can colonize disturbed areas including roadsides, abandoned railroad tracks, pastures, riverbanks, and recently logged forests. The best method to get rid of these plants is to deadhead the flower spikes before they produce seeds and then dig up the rest of the plant.

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Herb robert “Stinky Bob” (Geranium robertianum) Class B Noxious Weed

Herb robert escaped from ornamental plantings and thrives in forested communities asthe dominant ground cover, displacing native and beneficial plants such as trillium. Herb Robert's 5-petaled flowers are in all shades of pink and sometimes white. Overall the plant is covered with short glandular hairs, giving the plant a sticky feel and a distinct odor (sometimes this plant is known as "Stinky Bob"). Shallow, weak roots make this plant easy to pull although large infestations can be highly labor-intensive to remove.

 

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Scotch broom (Cytisus scoparius) Class B Noxious Weed

Scotch broom is one of the most well-known weeds in the northwest. Scotch broom iseverywhere and is very easy to identify. This plant is a perennial, evergreen shrub. This shrub has stiff, dark green branches with small lower leaves containing three lobes. Scotch broom has unmistakable bright yellow flowers similar to pea flowers in shape. This invasive species attacks many habitats such as poor, rocky soils, recently cleared areas, roadsides and fields. As it is seen everywhere when in bloom, scotch broom is very invasive to native plants and serves as a fire hazard during the dry months. On top of destroying our native plants, every part of the plant is poisonous if consumed. What’s the best way to get rid of it? It is true that you may never get rid of it all, but the more that is eliminated, the more chance there is for native plants to flourish. This being said, the best way to eliminate these shrubs is to team up with a community organization like Weed Warriors and pull away. Many smaller plants can be pulled by the base of the plant and you will be able to eliminate the roots as well. For larger, more mature plants a weed wrench will be necessary and very effective.

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