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700 cattle that were killed overnight by a poisonous weed.^[1]

A noxious weed is a plant species that has been designated by state or national agricultural authorities as a plant that is injurious to agricultural and/or horticultural crops and/or humans and livestock. Most have been introduced into a foreign ecosystem either by accident or mismanagement, but some are also native species. Typically they are plants that are aggressive growing which multiply quickly and adversely affect desirable plants or are somehow injurious to livestock or humans either by contact or when ingested. They are a large problem in many parts of the world, greatly affecting areas of agriculture, forest management and other open lands.

[edit] Criteria

Many noxious weeds have come to America through shipments of preferred seeds, some were introduced purposefully for garden plants. Idaho has about 300 exotic species present within the state but only 36 of those types are considered noxious weeds. In Idaho, the director of the Idaho State Department of Agriculture makes the legal designation of noxious on a type of weed. There are four criteria that the department uses for designation of a noxious weed:

1. It must be present in but not native to Idaho.
2. It must be potentially more harmful than beneficial to Idaho.
3. Eradication must be economically and physically feasible.
4. The potential adverse impact of the weed must exceed the cost of control.^[2]

[edit] Types

[edit] In Idaho

There are many types of noxious weeds that are poisonous to livestock. Grazing areas and open fields are susceptible to these weeds. Many of the weeds that are on the Idaho noxious weed list are just that.

• Leafy Spurge: came to America from Eurasia. This weed has a milky latex in all of the plant, this can produce blisters and dermatitis in humans, cattle, and horses and may cause permanent blindness if rubbed into the eye.
• Poison Hemlock: is native to Europe. It contains highly poisonous alkaloids toxic to all classes of livestock.
• Russian Knapweed: invades from the Caucasus in southern Russia and Asia. This weed causes chewing disease in horses.
• Tansy Ragwort: is originally from Eurasia. All parts are poisonous, it causes liver damage to cattle and horses, while it affects sheep to a lesser extent.
• Toothed Spurge: is native to the Great Plains region. A milky latex exists in all parts of the plant that can produce blisters and dermatitis in humans, cattle, and horses. This weed may cause permanent blindness if rubbed into the eye.
• Yellow Starthistle: originated in the Mediterranean area and Asia. It causes death and chewing disease in horses.
• Yellow toadflax: was brought from Europe, contains a poisonous glucoside that may be harmful to livestock.

Protecting livestock is very important, many livestock can be lost if the wrong weeds are in grazing fields (Prather, 27,45,53,67-73).^[2]

[edit] Control

1. Avoid driving in noxious weed-infested areas.
2. Don't transport plants that you can't identify
3. If you find noxious weeds with flowers of seeds, pull them out and leave them to dryout, or place in a plastic bag and throw them away
4. Use certified weed-free seeds^[3]

Maintaining noxious weeds and keeping levels low is very important, not just for livestock but also for humans. When maintaining noxious weeds it depends on the surrounding environment, the weed species, the habitat, and the availability of equipment and material. The law defines that control must be for eradication, prevention, or restoration. None of these objectives can be met without toil, time and money.^[3]

[edit] See also

• Invasive species
• Weed
• International Plant Protection Convention

[edit] References

1. ^ Coupe, Sheena, ed (1989). Frontier country: Australia's outback heritage. Vol. 1. Willougby: Weldon Russell. p. 298. 
2. ^ ^{a b}
   1. As stated by the University of Idaho, "Noxious weeds are a big problem and we need everyone's help to put in the effort to reverse the effects and keep more from spreading".
   Prather, Timothy (2002). Idaho's Noxious Weeds. University of Idaho. 
3. ^ ^{a b} "Idaho State Department of Agriculture". 2005. http://www.agri.idaho.gov/Categories/PlantsInsects/NoxiousWeeds/FAQs.php. Retrieved Nov 2008. 

[edit] External links

• Bureau of Land Management: Weeds
• US-Department of Agriculture: Invasive and Noxious Weeds
• Montana's Weed Awareness Program: Pulling Together
• Noxious Weed Photos, King County, Washington State
• USDA Noxious Weed Program

[edit] Additional reading

"Noxious weed free forage and straw certification program." 2006. State of Idaho. Nov. 2008 http://www.agri.idaho.gov

Taylor, Ronald. Northwest Weeds. Montana: Mountain Press Publishing Company, 1990.

U.S. Department of Agriculture Forest Services. Notes on Western Range Forbs. Washington: U.S. Government Printing Office, 1996.

Sheley, Roger, James Jacobs, and John Martin. "Integrating 2,4-D and sheep grazing to rehabilitate spotted knapweed infestations." Journal of Range Management (2004): Academic Search Premier. EBSCO Albertson's Library, Boise, ID. 04 Nov. 2008 http://www.jstor.org/stable/4003861

Roché, C T, et al. "Tracking an invader to its origins: the invasion case history of Crupina vulgaris." Weed Research 43.3 (June 2003): 177-189. Academic Search Premier. EBSCO. Albertson's Library, Boise, ID. 4 Nov. 2008 <http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=9732499&site=ehost-live>.