County Declared Noxious Weeds

  1. Category I

    Category I noxious weeds are weeds that are currently established and generally widespread in many counties of the state.

  2. Category II

    Category II noxious weeds have recently been introduced into the state or are rapidly spreading from their current infestation sites.

  3. Category III & IV

    Category III noxious weeds have not been detected in the state or may be found only in small, scattered, localized infestations. Category IV noxious weeds are invasive plants and may cause significant economic or environmental impacts if allowed to become established in Montana.

Madison County Weed List

Noxious Weed Species Common Name
Scientific Name
Field Scabious
Knautia arvensis
Musk Thistle
Carduus nutans