Noxious Weeds

Definition of a noxious weed


A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is injurious to agricultural or horticultural crops, natural habitats or ecosystems, or humans or livestock. Most noxious weeds have been introduced into an ecosystem by ignorance, mismanagement, or accident. Some noxious weeds are native. Typically they are plants that grow aggressively, multiply quickly without natural controls (native herbivores, soil chemistry, etc.), and display adverse effects through contact or ingestion. Noxious weeds are a large problem in many parts of the world, greatly affecting areas of agriculture, forest management, nature reserves, parks and other open space.

Many noxious weeds have come to new regions and countries through contaminated shipments of feed and crop seeds or were intentionally introduced as ornamental plants for horticultural use.

Utah noxious weed lists

As of 2023 the state of Utah has a total of 54 designated species on the Utah noxious weed list. These are separated into five different categories which have different priority and eradication goals. While all noxious weeds are a threat in Utah, special emphasis is placed on the various species that have NOT yet made it’s way into Utah. Research has proven that the earlier you can detect and respond to a new infestation, the more likely you are able to eradicate it before it spreads. This saves thousands if not millions of dollars in treatment efforts. 

Report a Noxious Weed

If you spot a noxious weed please use EDDMapS (our partner website) to report it. Upon successful verification, all reports get sent to the local county weed superintendents. 

Class 1A Early Detection Rapid Response

Plants not known to be in Utah, but thought to be present in neighboring states. If found in the state, swift eradication of any plants in this category is a very high priority.

Class 1B Early Detection

Plants that occur in Utah at very low levels. It is a high priority to eradicate all known populations, and prevent new ones.

Class 2 Control

Plants that have a reasonable distribution in Utah, but do not occur everywhere. These should be given a high priority for control.

Class 3 Contain

Plants widely distributed in Utah. The current populations of these plants should be contained to halt their spread. These plants should not enter commercial channels.

Class 4 Prohibited

Plants that are present in Utah, appear to be arriving in nursery stock/seed, and are being sold as ornamentals. This is now illegal.