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By Kale Williams

The high desert of Eastern Oregon, the lush stands of evergreens on our Cascade peaks and the flowering meadows of the coast range are all hiding a dirty secret. And it's hiding in plain sight.

Noxious weeds.

Invasive plant species might seem ho-hum to the typical Oregonian, but these noxious weeds are extremely costly to mitigate and prevent. Of the nearly two dozen profiled below, just two are responsible for roughly 95 percent of the estimated $83.5 million these plants cost in personal income, business sales and job losses across the state.

The data is culled from a

, commissioned by the Oregon Department of Agriculture, and includes the most-recent estimates available. The following list is organized from least to most costly, with some helpful tips at the bottom on how you can stop the spread of these invaders.

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Giant hogweed

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Terry English/USDA APHIS PPQ/Bugwood.org

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How it got here: This aptly-named monstrosity is native to the Caucasus Mountains in western Asia. Early in the 20th century, hogweed was planted in arboretums as a curiosity due to its massive size. It escaped the confines of managed gardens and quickly adapted to the surrounding areas, spreading throughout parts of Europe and North America, including parts of Maine, Maryland, New York, Washington and, more recently, the northwestern corner of Oregon.

How it impacts the environment: The giant hogweed poses a health hazard to humans. It exudes a clear watery sap that sensitizes skin to the sun. People who have been exposed to it have developed severe burns leading to blistering and dermatitis. Those blisters can turn into purple or black scars.

How big is the impact: The hogweed has yet to establish a firm foothold in Oregon, infesting less than 500 acres and causing less than $500 worth of economic impact. But state officials say that the state is home to more than 2 million acres of habitat where the plant could potentially flourish and the economic impact could exceed $1 million if it were to spread.

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Kudzu

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How it got here: At the 1876 Centennial Exposition in Philadelphia, the Japanese government presented its U.S. counterparts with an elaborately constructed garden filled with plants native to Asia, among them, kudzu. Its sweet smell and large leaves endeared the plant to gardeners in this country who began using the plant as an ornamental garden addition. In the 1930s, the Soil Conservation Service marketed kudzu as an easy way to control erosion before declaring the fast-growing weed an invasive species.

How it impacts the environment: Kudzu kills native plants, trees and shrubs by smothering them with a nearly-impenetrable blanket of leaves and wrappits viney tentacles around stems and tree trunks. Kudzu vines can reach 4 inches in diameter and the sheer weight of the plant, which can grow a foot per day, has been known to break branches and bring down whole trees. Kudzu taproots, which can support as many as 30 vines, can reach immense proportions, sometimes weighing up to 400 pounds.

How big is the impact: Despite their size, kudzu has only infested about 500 acres in Oregon with an economic impact of less than $500, but some 700 million acres are susceptible to the invasive weed, which, if infested, could bring damages upwards of $100 million.

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Mediterranean sage

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Courtesy/Oregon Department of Agriculture

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How it got here: This plant, known as Med sage for short, hitched a ride from its native Europe on some contaminated alfalfa seeds in the 1890s.

How it impacts the environment: Though not widespread, the Med sage has proved bothersome in pastures and rangelands, especially in the south and central regions of Oregon. Highly competitive, it easily replaces grasses and other important grazing material.

How big is the impact: Though the med sage has infested more than 90,000 acres in Oregon, the annual economic impact is thought to be less than $500.

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Purple starthistle

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Wikimedia Commons/Philmarin

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How it got here: It's unclear how it got here, but the purple starthistle is native to Mediterranean Europe and North Africa.

How it impacts the environment: This heavily armored pioneering species prefers fields, roadsides, grasslands, rangelands, waste areas, and open forests, where it displaces native species. Highly adaptable, the starthistle thrives in the arid eastern part of the state as well as the rain-soaked western valleys. Its long taproots give it an advantage over native species and degrades grazing quality of fields.

How big is the impact: The starthistle has infested roughly 500 acres with an economic impact of less than $500 a year. An additional 4 million acres are susceptible to the weed.

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Squarrose knapweed

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Courtesy/Steve Dewey/Utah State University

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How it got here: Native to Southern Asia and the Middle East, it's a bit of a mystery exactly when and how squarrose knapweed came to the U.S. It can now be found all over the American West including Oregon, Wyoming, California, Nevada and Utah, where it has infested more than 200,000 acres in three counties.

How it impacts the environment: While it hasn't taken a firm foothold in Oregon yet, it could have potentially devastating impact for the rangelands of the eastern region because it forms dense stands capable of pushing out native bunchgrasses. "The economic and environmental costs of large-scale infestations would be high. Rangeland in Oregon supports the vital livestock industry, as well as providing habitat for sage grouse, antelope and numerous rare plants," the Oregon Department of Agriculture said.

How big is the impact: While the current infestation is small, less than 500 acres with less than $500 in annual economic impact, the potential for large-scale infestation is high. More than 14 million acres are prime for squarrose knapweed invasion, representing a potential yearly economic impact of more than $2 million.

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Meadow and Orange hawkweed

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How it got here: A native of the European continent, it's unclear exactly when and how the hawkweed landed in Oregon, but it has strikingly colorful flowers and there is speculation it was brought here intentionally by plant enthusiasts.

How it impacts the environment: The hawkweed produces mats of rosettes that effectively blanket the ground, preventing native plants from taking root. Decaying leaves from the hawkweed release alleopathic chemicals, which hinder the growth and germination of other plants. While they haven't infested a ton of space in Oregon, these invasive weeds pose a threat to meadows, prairies, pastures and lawns.

How big is the impact: Plants from the hawkweed complex have infested roughly 1,000 acres in Oregon, with an annual economic hit of around $1,000. Experts say, however, that nearly 18 million additional acres are susceptible to the plant.

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Scotch thistle

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How it got here: Introduced as an ornamental in the 1800s from its native environs of Asia and Europe, the scotch thistle quickly spread and is now found throughout North America.

How it impacts the environment: Known as a wasteland weed, scotch thistle forms dense canopies in irrigation canals and anywhere with well-drained soils. It can invade farmland and has become a major issue in northeast Oregon and has been documented spreading to the central region of the state.

How big is the impact: Though scotch broom has infested more than 100,000 acres, its annual economic impact is only around $6,000.

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Leafy spurge

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Wikimedia Commons/Ivar Leidus

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How it got here: An aggressive herb native throughout Europe and Asia, leafy spurge arrived in the U.S. concealed in contaminated grain in the late 1800s and was first spotted in Oregon around 1930 in Klamath County.

How it impacts the environment: Incredibly invasive and hard to control, leafy spurge also contains a milky sap that can be poison to livestock and dangerous to humans who come in contact with it. The plant prefers prairies, savannas, pastures and abandoned fields. Because it dominated other plants so easily, leafy spurge can cut the productivity of rangelands by 50 to 75 percent. The toxic sap can be fatal to cattle, though some sheep and goats have acclimatized to it, and it can cause skin irritation to humans or blindness if rubbed in the eyes.

How big is the impact: Currently, more than 8,000 acres in Oregon have been infested by leafy spurge, with an annual economic impact of $17,000.

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Japanese knotweed

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Wikimedia Commons/MdE

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How it got here: Native to Eurasia, this herbaceous perennial was brought to North America as an ornamental species, but quickly escaped its confines and became a prolific invader across nearly all of the continental U.S. and parts of Canada.

How it impacts the environment: The knotweed can reach heights of up to 9 feet tall and grows vigorously along streams, roadside ditches, waste areas and riverbanks. Dense stands of knotweed can impede the growth of native trees. Once established, the plant is extremely hardy, resistant to cutting and, oftentimes, can only be controlled with herbicides, which are both costly and time consuming.

How big is the impact: Japanese knotweed currently infests more than 42,000 acres across Oregon, mostly concentrated in the northwest corner, with an annual economic cost of $31,000.

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Spotted knapweed

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Wikimedia Commons/Sylae Jiendra Corell

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How it got here: Accidentally imported from Europe in the late 1800s in contaminated seeds and soil, spotted knapweed is now found in nearly all of the continental U.S.

How it impacts the environment: Though it hasn't yet become widespread in Oregon, spotted knapweed is one of the most dominant invasive weeds in the western U.S., especially in in the northern Rocky Mountains. It forms dense stands on pretty much any open area disrupting growth in native species important for grazing and foraging wildlife. On heavily infested rangeland, the cost of getting rid of spotted knapweed is often far higher than the money-earning potential of the land. These plants, and those like them, "have more negative impacts attributed to them in natural and agricultural ecosystems than any other plant group in the western U.S.," according to the Oregon Department of Agriculture.

How big is the impact: The spotted knapweed has infested more than 168,000 acres with an annual economic impact of $33,000. But there are an additional 37 million acres of susceptible land in the state which, if infested, could cost more than $138 million.

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Diffuse knapweed

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Wikimedia Commons/Thayne Tuason

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How it got here: Native to the Mediterranean region, Diffuse knapweed was first introduced to the Pacific Northwest in the early 20th century in contaminated alfalfa seed from Turkmenistan or Germany. These single-stemmed, biennial plants form rosettes, then bolt and flower, growing up to 3 feet tall within two years.

How it impacts the environment: The knapweed forms dense stands, typically on rangeland in central and northeast Oregon. It can grow in a wide variety of environments including open prairie, sandy riverbanks, rocky outcroppings and along roadsides. It reproduces by seed, usually spread by windblown tumbleweeds or carried on the fur of animals. Once it has established itself, removal is often more costly than the income potential of the land it inhabits. The plant juice that oozes from the stems can be hazardous and experts recommend wearing gloves whenever handling, as mature plants are scratchy and often host mites.

How big is the impact: Diffuse knapweed currently infests more than 275,000 acres and has an annual economic impact of $36,000.

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Perennial pepperweed

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Wikimedia Commons/Michael Becker

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How it got here: Native to Southern Europe and Western Asia, the pepperweed is thought to have come to the U.S. in the 1930s, embedded in contaminated sugar beet seed.

How it impacts the environment: Highly adapted to a wide variety of soil conditions, perennial pepperweed rapidly colonizes wetlands, estuaries and moist pastures. It degrades bird nesting habitat and infests hay meadows. Hay that has been contaminated with pepperweed suffers in quality and can significantly affect land values where it has invaded.

How big is the impact: More than 90,000 acres of Oregon have been infested with perennial pepperweed to the tune of some $110,000 per year.

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Meadow knapweed

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How it got here: A hybrid of black and brown knapweed, this plant was first noted in Oregon in 1910 after being brought here from its native Europe. It's unknown if hybridization occurred here or before it arrived.

How it impacts the environment: Knapweed competes with other grasses and prairie species causing a decline in native plant productivity. It prefers moist areas and has the potential to invade roadsides, riverbanks, sand or gravel bars and irrigated pastures.

How big is the impact: Meadow knapweed has infested more than 125,000 acres in Oregon, with an annual economic impact of $146,000.

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Dalmatian toadflax

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Wikimedia Commons/Ghislain118

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How it got here: Native to the Dalmatian coast of Croatia, the toadflax is thought to have been brought to the U.S. in the mid-1800s as an ornamental plant.

How it impacts the environment: This toadflax establishes deep roots that compete with native species in rangelands, pastures and along railways. Mature plants are capable of producing more than half a million seeds per year and the plant contains chemicals toxic to livestock.

How big is the impact: Dalmatian toadflax currently infests more than 345,000 acres in Oregon with an economic impact of $254,000 per year.

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Gorse

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Wikimedia Commons/Rosser1954

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How it got here: Native to Europe, gorse was originally cultivated in the U.S. as an ornamental shrub. Like the giant hogweed, this perennial, spiny evergreen, which can grow up to 9 feet tall, escaped from the gardens of North American and spread prolifically, especially on the west coast.

How it impacts the environment: Gorse is a spinney, pioneer species that grows quickly and crowds out native species. It grows in dense stands that render infested land unusable, harming forest production and inhabiting everything from parklands to pastures. It costs a ton to control gorse and seeds have a long life, making re-infestation a near-constant threat. Gorse is also a very oily plant making for extreme fire hazards wherever it is found.

How big is the impact: More than 28,000 acres are infested in Oregon with an economic impact of nearly $500,000 annually. The Oregon Department of Agriculture says that another 16.5 million acres in the state are susceptible to the weed.

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Whitetop

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Wikimedia Commons/Kurt Stüber

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How it got here: Native to southwest Asia and eastern Europe, this weed likely came to the U.S. in contaminated grains in the early part of last century.

How it impacts the environment: Whitetop, a perennial species, thrives in alkaline soils, but is not restricted to them. It grows so densely that it can completely dominate whatever habitat it grows in. It isn't toxic to livestock, but most stock animals avoid whitetop so its presence can ruin prime grazing habitat.

How big is the impact: Whitetop currently infests more than 190,000 acres in Oregon, almost exclusively in the east, with an annual economic impact of about $559,000.

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Yellow starthistle

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How it got here: Yellow starthistle was first spotted in Oregon's Deschutes County in 1933, probably brought in contaminated seeds or on the back imported livestock.

How it impacts the environment: Starthistle grows dense and spreads rapidly, especially in canyon grasslands, rangelands, pastures and edges of cropland. It's aggressive and highly adaptable and has been found in wheat fields as well. This plant is toxic to horses, causing "chewing disease" in the animals, and can injure hunting dogs.

How big is the impact: Yellow starthistle currently infests more than 376,000 acres across the state with an annual economic impact of $774,000.

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Rush skeletonweed

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Wikimedia Commons/Franz Xaver

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How it got here: It's unclear how it got to the Pacific Northwest, but this invasive weed, native to Eurasia, now infests several million acres in the region, especially in Idaho.

How it impacts the environment: An aggressive plant that infests both crop and rangeland, skeletonweed grows in dense stands that crowd out native plants and important crops like cereal grain and potatoes. The latex sap of skeletonweed gums up harvesting machines and, despite years of abatement projects, new sites are being found in Oregon every year.

How big is the impact: More than 110,000 acres have been infested in Oregon with an annual economic impact of nearly $1.4 million.

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Scotch broom

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Courtesy/Oregon Department of Agriculture

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How it got here: A native of Europe, scotch broom was brought to North America in the late 1700s as an ornamental plant. It was first documented in Oregon in Benton County in 1892.

How it impacts the environment: Easily the most recognizable of the invasive weeds, scotch broom is among the most costly as well. It easily invades dunes, forestlands, natural areas and parks. Because it grows so rapidly and produces so many seeds, which can last for up to 50 years, scotch broom demands aggressive, long-term control tactics to mitigate its harm on native plants.

How bigs is the impact: Scotch broom has infested more than 1.5 million acres in Oregon and costs more nearly $40 million a year to control.

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Armenian/Himalayan Blackberry

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How it got here: It's unclear exactly how they showed up in Oregon, but the Armenian Blackberry, also called the Himalayan Blackberry, was first spotted in Marion County in 1922. Their fruits are delicious, but these rapacious plants are costly.

Among the most-widespread and economically devastating of all the invasive plants in Western Oregon, this fruiting berry has root buds that produce trailing, reddish stems and sharp, prickly spines. Their flowers sport five pedals that range from white to light pink.

How it impacts the environment: The Armenian blackberry spreads by seed, often carried by birds and animals. It's capable of jumping great distances and, with a growth rate of up to 20 feet per year, they can take over entire landscapes. This blackberry crowds out native species and "and has a significant economic impact on right-of-way maintenance, agriculture, park maintenance and forest production," according to the Oregon Department of Agriculture. Also, those prickly spines are super sharp, according to anyone who's ever tried to tame them.

How big is the impact: The Armenian blackberry is currently infesting more than 1.6 million acres, mostly in Western Oregon, and has an annual economic impact of more than $40 million.

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-- Kale Williams

kwilliams@oregonian.com

503-294-4048

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So what can you do?

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With hundreds of thousands of acres already infested, and many more susceptible, the prospect of stopping the spread of noxious weeds can be daunting.

But there are ways everyone can do their part, said Tom Forney, project coordinator for the Oregon Department of Agriculture's noxious weed control program.

"We tell people to check with their local authorities, either city or county, on which specific plants are causing problems in their area," he said. "People should also be checking shoes, boots and pets to try and avoid introducing these invasives into new areas."

That last piece of advice is part of a program known as "

which aims to stop the spread of invasive plants and animals.

Forney said the best way to stop the spread of these costly weeds is to find them before they become widespread.

"Being aware of new invaders is probably the best thing we can do," he said. If you spot any of the above-mentioned species in a new area, Forney said you can call the invasive species hotline at 1-866-INVADER or make an

.

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