- "Russian knapweed roots may grow 20 feet deep. The plant, when ingested for a prolonged period by horse, impairs the animal's ability to move its jaw and chew its food. The tongue is impaired, but swallowing is normal. Animal must be destroyed or it will die of thirst and starvation." - Dr. George Beck, CSU
- "Sheep are the only grazing animals that can eat leafy spurge."
- Dr. George Beck, CSU, Denver Post 7-21-96 - "The spread of diffuse knapweed has been like wildfire, sending out fingers along roads, spot infestations in disturbed sites, and the eventual coalescing of the spots."
- "Approximately 3.1 million acres in western U.S. are infested with diffuse knapweed." - Dr. Ben Roché, Washington State University
- "Aphthona nigriscutis (flea beetle predator of leafy spurge) has been the most successful biological control agent for leafy spurge. A release of 250 adults near Minot, North Dakota in 1989, increased to over a million by 1993." - Dr. Rod Lym, North Dakota State University
- "If you remove 2 or 4 inches of taproot of diffuse knapweed, only 4 percent of the plants will survive. If no taproot is removed, 38 percent will survive." - Dr. Ben Roché, Washington State University
Definition of Noxious Plant: An alien (non-native to Colorado or to the native plant community where it is found) plant which aggressively invades or is detrimental to crops or native plants and/or is poisonous to livestock, and/or is a carrier of detrimental insects, diseases or parasites and/or is detrimental to the environmentally sound management of natural or agricultural ecosystems. C.R.S. Article 5.5 Section 35-5.5-103 (16).
State and County Law: After the county has controlled the noxious weeds on the right-of-way near your land and has notified you that you have noxious weeds, you are obliged to control the noxious weeds, or the county may send a spraying company to do the work and the bill will be added to your property tax. Landowners should, however, make control efforts long before the county notifies.
Persistence Pays: Although each species has its peculiarities, stress is one key to control. Also, catching early infestation may eradicate it. Using many kinds of controls at once, such as mowing, pulling, tilling some plants, grazing, insects, fertilizing, watering and sowing grasses all tend to keep the noxious plant under control. Until we have natural predators, mainly insects which control the plants in their native habitat, we probably won't see natural control in the near future.
| Need more information? |  Colorado State University AnswerLink! |