Idaho's Noxious Weeds


What are noxious weeds?

Noxious weeds are plant species that are non-native and invasive by nature. Many of these species make significant modifications to the landscape. Idaho currently has 64 listed noxious weeds throughout the state. There are different categories of control for each noxious weed as stipulated in the Idaho Administrative Procedures Act 02, title 06, chapter 22, “Noxious Weed Rules.” The categories affect how each weed is managed.

Statewide early detection and rapid response (EDRR) – plants in this category must be reported to the Idaho State Department of Agriculture (ISDA) within 10 days after being identified at the University of Idaho or by another qualified authority approved by the ISDA director. Eradication of these weeds must begin in the same season they are found.

Statewide control – plants in this list may already exist in some parts of the state. In some areas of the state control or eradication is possible and a plan must be written that will reduce infestations within five (5) years.

Statewide containment – plants in this category exist in the state. New or small infestations can be reduced or eliminated, while established populations may be managed as determined by the weed control authority, which is usually the county weed program.

Idaho's 64 Noxious Weeds

Idaho has 64 different species of weeds which are designated noxious by state law. These weeds are designated into three levels of concern. The spread of these weeds and the damage they do to Idaho agriculture can be lessened through proper identification and handling.

*** Temporarily Listed Noxious Weeds

Water Hyacinth
Sticky Nightshade

Statewide EDRR List

Common Name Map Scientific Name
Brazilian Elodea Egeria densa
Common/European Frogbit Hydrcharis morsus-ranae
Fanwort Cobomba caroliniana
Feathered Mosquito Fern Azolla pinnata
Giant Hogweed Heracleum mantegazzianum
Giant Salvinia Salvinia molesta
Hydrilla Hydrilla verticillata
Policeman's Helmet Impatiens glandulifera
Squarrose Knapweed Centaurea triumfetti
Syrian Beancaper Zygophyllum fabago
Tall Hawkweed Hieracium piloselloides
Variable-Leaf-Milfoil Myriophyllum heterophyllum
Water Chestnut Trapa natans
Yellow Devil Hawkweed Hieracium glomeratum
Yellow Floating Heart Nymphoides pelata

Statewide Control List

Common Name Map Scientific Name
Black Henbane Hyoscyamus niger
Bohemian Knotweed Polygonum bohemicum
Buffalobur Solanum rostratum
Common Crupina Crupina vulgaris
Common Reed (Phragmites) Phragmites australis
Dyer's Woad Isatis Tinctoria
Eurasian Watermilfoil Myriophyllum spicatum
Giant Knotweed Polygonum sachalinense
Japanese Knotweed Polygonum cuspidatum
Johnsongrass Sorghum halepense
Matgrass Nardus stricta
Meadow Knapweed Centaurea debeauxii
Mediterranean Sage Salvia aethiopis
Musk Thistle Carduus nutans
Orange Hawkweed Hieracium aurantiacum
Parrotfeather Milfoil Myriophyllum aquaticum
Perennial Sowthistle Sonchus arvensis
Russian Knapweed Acroptilon repens
Scotch Broom Cytisus scoparius
Small Bugloss Anchusa arvensis
Vipers Bugloss Echium vulgare
Yellow Hawkweed Hieracium caespitosum

Statewide Containment List

Common Name Map Scientific Name
Canada Thistle Cirsium arvense
Curlyleaf Pondweed Potamogeton crispus
Dalmatian Toadflax Linaria dalmatica ssp. dalmatica
Diffuse Knapweed Centaurea diffusa
Field Bindweed Convolvulus arvensis
Flowering Rush Butomus umbelltus
Hoary Alyssum Berteroa incana
Houndstongue Cynoglossum officinale
Jointed Goatgrass Aegilpos cylindrica
Leafy Spurge Euphorbia esula
Milium Milium vernale
Oxeye Daisy Leucanthemum vulgare
Perennial Pepperweed Lepidium latifolium
Plumeless Thistle Carduus acanthoides
Poison Hemlock Conium maculatum
Puncturevine Tribulus terrestris
Purple Loosestrife Lythrum salicaria
Rush Skeletonweed Chondrilla juncea
Saltcedar Tamarix sp.
Scotch Thistle Onopordum acanthium
Spotted Knapweed Centaurea stoebe
Tansy Ragwort Senecio jacobaea
White Bryony Bryonia alba
Whitetop Cardaria draba
Yellow Flag Iris Iris psudocorus
Yellow Starthistle Centaurea solstitialis
Yellow Toadflax Linaria vulgaris