Common Noxious Weed Overview

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Spotted Knapweed

Name: Spotted Knapweed (Centaurea stoebe)

Introduction: From Eurasia as a contaminant of alfalfa and clover seed

Habitat: Any disturbed soil

Infestation: Vacant lots, pastures, rangeland, roadsides, stream banks and landscaping

Available Control: Mechanical, chemical, and biological

Priority of Control: Preventing plant from going to seed, attack in rosette stage

Biological Controls: For more information about these biological control agents of Spotted Knapweed, please visit WSU Extension Integrated Weed Control Project.

For More Detail: Visit the Washington Noxious Weed Control Board listing for Spotted Knapweed.  

 

 

Canada Thistle

Name: Canada Thistle (Cirsium arvense)

Introduction: Native to southeastern Eurasia, contaminated crop seed

Habitat: Rich, heavy loam, clay loam, and sandy loam, with an optimum soil depth of 20 inches

Infestation:  Crops, pasture, rangeland, roadsides, stream banks and landscaping. It can crowd out forage

grasses by up to 60 percent. It can also invade native plant communities.

Available Control: Mechanical, chemical, biological

Priority of Control: Deplete its root reserves before rosette has a chance to over-winter.

Biological controls: For more information about the biological control of Canada Thistle, please visit WSU Extension Integrated Weed Control Project.

For More Detail: Visit the Washington Noxious Weed Control Board listing for Canada Thistle.  

 

 

Common Bugloss

Name: Common Bugloss (Anchusa officinalis)

Introduction: From Eurasia as a contaminant of alfalfa and clover seed

Infestation: Pastures and rangelands and is a concern to alfalfa production because the succulent leaves and stalks mold the hay once it is baled.

Available control: Chemical, and mechanical

Priority of Control:  The most effective control of Common Bugloss is prevention. Above all, prevent plants from going to seed.

Biological Control: There is no known effective biological control for Common Bugloss

For More Detail: Visit the Washington Noxious Weed Control Board listing for Common Bugloss.   

Dalmatian Toadflax  

Introduction: Native of southeastern Europe and introduced as an ornamental plant because of its snapdragon-like flowers.

Habitat:  Coarse, well-drained soils

Infestation: Roadsides and rangelands, in fields, overgrazed pastures, idle cropland and waste areas.

Available control: Mechanical, Chemical, Biological

Priority of Control:  Prevent from flowering, keeping foliage down without spreading root fragments

Biological Control: For more information about the biological control of Dalmatian Toadflax, please visit WSU Extension Integrated Weed Control Project

For More Detail: Visit the Washington Noxious Weed Control Board listing for Dalmatian Toadflax.   

 

 

Rush Skeletonweed

Name: Rush Skeletonweed (Chondrilla juncea)

Introduction: Central Asia and the Mediterranean Basin including North Africa, Morocco, Turkey, Italy, Spain and Portugal.

Habitat: Well-drained, sandy-textured or rocky soils.

Infestation: Rangelands, semi-arid pastures, croplands, transportation right-of-ways, residential properties and other areas subjected to repeated soil disturbance.

Available control: Mechanical, chemical, and biological. 

Priority of Control:  Prevent root fragments from producing new plants, prevent from seeding

Biological Control: For more information about the biological control of Rush Skeletonweed, please visit WSU Extension Integrated Weed Control Project

For More Detail: Visit the Washington Noxious Weed Control Board listing for Rush Skeletonweed.

 

Hoary Alyssum  

Name: Hoary Alyssum (Berteroa incana) 

Introduction: European plant in either contaminated lawn seed or hay

Habitat: Adapted to dry soils and can out compete other plants.

Infestation: Waste places, overgrazed pastures, and stressed meadows.

Available control: Mechanical and chemical 

Priority of Control: Prevent plant from getting to flower.

Biological Control: There are no insects for biological control of hoary alyssum available at this time.

For More Detail: Visit the Washington Noxious Weed Control Board listing for Hoary Alyssum.

 

You can also contact Pend Oreille Weed Control Board for a list of more invasive weeds and request materials at: noxweedinfo@pendoreille.org or 509-477-2402 or visit their website here.