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Montana State-listed Invasive and Noxious Weeds

Category 1 noxious weeds are weeds that are currently established and generally widespread in many counties of the state. Management criteria includes awareness and education, containment and suppression of existing infestations and prevention of new infestations. These weeds are capable of rapid spread and render land unfit or greatly limit beneficial uses.

Canada Thistle
Field Bindweed
Whitetop Complex aka Hoary Cress
Leafy Spurge
Russian Knapweed
Spotted Knapweed
Diffuse Knapweed
Dalmatian Toadflax
St. Johnswort
Sulfur Cinquefoil
Common Tansy
Ox-eye Daisy
Houndstongue
Yellow Toadflax

Category 2 noxious weeds have recently been introduced into the state or are rapidly spreading from their current infestation sites. These weeds are capable of rapid spread and invasion of lands, rendering lands unfit for beneficial uses. Management criteria includes awareness and education, monitoring and containment of known infestations and eradication where possible.

Dyers Woad
Purple Loosestrife aka Lythrum
Tansy Ragwort
Meadow Hawkweed Complex
Orange Hawkweed
Tall Buttercup
Saltcedar aka Tamarisk
Perennial Pepperweed

Category 3 noxious weeds have not been detected in the state or may be found only in small, scattered, localized infestations. Management criteria includes awareness and education, early detection and immediate action to eradicate infestations. These weeds are known pests in nearby states and are capable of rapid spread and render land unfit for beneficial uses.

Yellow Starthistle
Common Crupina
Rush Skeletonweed
Eurasian Watermilfoil
Yellow Flag Iris

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