Noxious Weeds – The Cancer on Our Land

Control and managing Idaho’s 67 noxious weed species requires an understanding of the problem, and that begins with detection and identification of noxious weeds.

Noxious weeds cost millions of dollars to Idaho by:

  • Fouling recreation sites from use
  • Chocking streams and waterways
  • Poisoning and injuring livestock and humans
  • Crowding out beneficial native plants
  • Degrading wildlife habitat
  • Creating wild fires in our forests and Idaho’s range land

The spread of noxious weeds in Idaho may signal the decline of entire ecological watersheds. They severely impact the beauty and create widespread economic losses. Noxious weeds are huge problems for our urban as well as rural areas, and for private, state, and federal lands. Valley County noxious weed species spare no segment of society – rancher, hunter, hiker’s and fisherman alike – and when unmanaged they spread rapidly and unceasingly and silently.

Noxious weeds pose a serious threat to all Idahoans and to the land we call home.

Booklets available with information about the 67 noxious weeds in Idaho, University of Idaho – Extension Office.

Also see the State of Idaho Noxious Weed site


It shall be the duty and responsibility of all landowners to control noxious weeds on their land and property, in accordance with Title 22, Chapter 24 (22-2407).

When a property owner has failed to control noxious weeds, Idaho Code states that the county weed control authority, after due notice, take control measures to prevent the spread of noxious weeds. This will be done by having the property treated and the cost billed to the property owner.

Noxious weeds presently in Valley County include: Eurasian Watermilfoil, Orange Hawkweed, Canada Thistle, Dalmatian Toadflax, Diffuse Knapweed, Field Bindweed, Houndstongue, Leafy Spurge, Oxeye Daisy, Poison Hemlock, Puncturevine, Rush Skeletonweed, Scotch Thistle, Spotted Knapweed, Tansy Ragwort, Whitetop and Yellow Toadflax.

Additional noxious weeds within the state are: Yellow Starthistle, Yellow Flag Iris, White Bryony, Saltcedar, Purple Loosestrife, Plumeless thistle, Perennial Pepperweed, Milium, Jointed Goatgrass, Hoary Alyssum, Flowering Rush, Curlyleaf Pondweed, yellow Hawkweed, Vipers Bugloss, Small Bugloss, Scotch Broom, Russian Knapweed, Perennial sowthistle, Parrotfeather Milfoil, Musk Thistle, Mediterranean Sage, Meadow Knapweed, Matgrass, Johnsongrass, Japanese Knotweed, Giant Knotweed, Dyer’s Woad, Common Reed (Phragmites), Common Crupina, Buffalobur, Bohemian Knotweed, Black Henbane, Yellow Floating Heart, Yellow Devil Hawkweed, Water Chestnut, Variable-Leaf-Milfoil, Tall Hawkweed, Syrian Beancaper, Squarrose Knapweed, Policeman’s Helmet, Hydrilla, Giant Salvinia, Giant Hogweed, Feathered Mosquito Fern, Fanwort, Common European frogbit and Brazilian Elodea.

For help with identification, control methods, spray equipment to loan and information about our CWMA cost share program, contact Valley County Weed Control at 55 Gold Dust Road or call (208)382-7199.


Steve Anderson

Department Supervisor
Valley County Weed Department

Office (208)382-7199
Fax: (208)382-7198

Matt Voile

Idaho State Department of Agriculture
Noxious Weeds/Invasive Species

Section Manager

Dan Safford

Idaho State Department of Agriculture
Noxious Weeds & Grasshopper/Mormon cricket Control
AG Program Specialist

Office: (208)332-8650