Profiles of weeds on the least-wanted list.


Mar 11, 2001
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Profiles of weeds on the least-wanted list.

Dan Hansen - Staff writer , the Spokane Spokesman Review.

These profiles of weeds infesting the Northwest are based on information from the U.S. Department of Agriculture, Washington State Noxious Weed Control Board, the Nature Conservancy, the University of Idaho and Gary Piper, an entomologist at Washington State University.

•Purple loosestrife -- A perennial that reaches heights of 12 feet, loosestrife has a spike of showy blossoms. Dioscorides, a first-century Greek physician, used it to stanch bleeding and cure dysentery among soldiers. Beekeepers value its pollen.

Loosestrife can crowd out cattails and other wetlands plants important to wildlife.

Botanists believe loosestrife came to New England in the mid-1800s, possibly through seeds clinging to imported wool. Gardeners likely brought some seeds to America intentionally.

Loosestrife first was reported in Washington in 1929. In 1992, entomologists released three species of beetles in the Columbia Basin to feed on a 23,000-acre infestation. More of the bugs were released on a five-acre infestation at St. Maries, Idaho, in 1998.

The insects have reduced loosestrife in the basin to scattered plants, and are beginning to beat back the plant at St. Maries. It is one of biggest successes in the use of biological controls against Northwest weeds.

•Yellow starthistle -- This member of the daisy family showed up in the United States in the 1800s, and in Washington in the 1920s. Botanists believe it was a contaminant in hay imported from Europe.

It now infests 23 states, including California, Idaho and Washington. It lends a velvety yellow to many slopes overlooking the Snake and Clearwater rivers in Idaho.

Yellow starthistle crowds out native grasses, leaving little to support livestock or wildlife. It can be toxic to horses and creates a fire hazard after it dries out in late summer.

Since 1985 in Washington, entomologists have released four species of beetles and two flies to eat the seeds of starthistle. Results are promising, although it continues to spread.

•Spotted and diffuse knapweed -- These cousins cover more than 10 million acres of the West, including 4 million acres in Montana and more than 2 million acres of Idaho.

Washington records show knapweed infests at least 500,000 acres, although estimates range as high as 1.5 million acres.

Growing to 48 inches, knapweed generally has flowers of pink, purple or white. The plants have stiff, spreading branches and spiny bracts.

Botanists say both species came to North America around the start of the 20th century, probably as a contaminant in alfalfa seed.

Since the mid-1970s, American scientists have unleashed eight insects on knapweed. One, a beetle imported from Greece in the mid-1990s, "has proven quite spectacular in controlling knapweed," Piper said.

•Rush skeletonweed -- A nearly leafless tangle of stem and branches, it has half-inch yellow flowers.

Skeletonweed grows in both cultivated fields and rangeland. Its wiry stems and rubbery sap can gum up machines used to harvest wheat, alfalfa and other crops.

Botanists believe skeletonweed came to the northeastern United States in the 1870s. It was reported in Spokane County in 1938, and has since infested an estimated 2 million acres of the state. It grows on about 3.5 million acres of Idaho, where it first was documented in 1960s.

Over the past 30 years, scientists have introduced three insects and two pathogens that attack skeletonweed. A moth introduced in recent years shows hope of finally gaining control of the plant.

•Canada thistle -- Colonists inadvertently brought the purple-flowered thistle to the New World in the 17th century. By 1881, it had spread across the continent, prompting Washington's territorial legislature to pass a law requiring landowners to fight the thistle.

It is found in forests, cultivated fields, pastures and rangelands, and can serve as a host for insect pests that attack crops.


Well-known member
Mar 19, 2001
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A couple years ago there was a story in the local paper that said they were letting some china bug loose on the yellow starthistle in the Sutter Buttes as a test.  I have never seen or heard the how that worked.  I was hoping it it would, cause as we all know that stuff is a pain in the ass.  More than likely though we just got another pest is all.


Well-known member
Mar 13, 2001
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I hope it eats spotted owls and red leg frogs too.    Fubar

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