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Frequently Asked Questions
What are noxious weeds?
A weed is designated noxious when it is considered by a governmental agency to be injurious to public health, agriculture, recreation, wildlife, or property. Most noxious weeds are non-native plants that are serious pests because they cause economic loss and harm the environment. Noxious weeds choke out crops, destroy range and pasture lands, clog waterways, affect human and animal health, and threaten native plant communities. In Oregon noxious weed designation is covered under Oregon Administrative Law 603-052-1200.
How are noxious weeds different from regular weeds?
In Oregon federal, state or county laws designate plants as "noxious" if they are overl aggressive, difficult to manage, parasitic, poisonous, carriers or hosts of serious insects or diseases. In Oregon noxious plants are non-native, new to, or not common in the state. In most cases noxious weeds have a direct impact on croplands, wildlife habitat, riparian ecosystems, and range land.
Are these plants noxious or invasive in their host countries?
For the most part, no. These plants have existed for centuries in their host county, but their populations have been kept to manageable levels naturally by other plan competition, insects, pathogens and a host of other predators. When plant populations in these countries of origin increase, insects and other predators increase accordingly to help keep them in check.
How did these weeds get here and where did they come from?
Noxious weeds and non-native invaders began to appear and spread with European settlement and continue to arrive today. Most of Oregon’s least desirable weeds are of Mediterranean, European, and Asian origin. The introduction of non-native invasive plants has increased dramatically in the past decade due to the increased ease and speed of world travel and the expansion of global commerce. Local spread of noxious weeds can be natural by wind, water, and animals; but human activities such as, recreation, vehicle travel, and the movement of contaminated equipment, products, and livestock often greatly increase the distance and rate of dispersal.
How are these weeds spread?
Weeds are spread in any number of different ways: by human activity, birds, animals, wind, water, vehicles, and seed and plant parts, to name a few.
I heard that butterfly bush is a listed noxious weed.
If you planted your butterfly bush before it was listed (2004) you do not have remove it, but you are required to prevent it from propagating. You must deadhead the plant after blooming to prevent the seeds from spreading. Or better yet, replace your butterfly bush with some other native or non-invasive plants. Your local nurseries can help you chose a wide range of shrubs that can replace your butterfly bush.

How can I get my neighbors to control their weeds?
Try talking to your neighbors first and explain calmly the importance of controlling weeds. Depending on where you live, there may be local programs that mandate the control of noxious weeds on private property. Homeowner associations can direct weed control to their members. Some local government entities have codes or regulations that mandate weed control. Also, some areas have Noxious Weed Control Districts or Weed Management Areas that can help your neighbors control their weeds either by education and outreach, land management strategies, and/or funding. Nonetheless, weed control is everybody’s business.