In 2010 the Montana Department of Agriculture revamped the noxious weed priority system.  Noxious weeds are now rank one of 5 priorities.
Priority 1A - These weeds are not present in Montana. Management criteria will require eradication of detected; education and prevention.
Priority 1B – These weeds are have limited presence in Montana. Management criteria will require eradication or containment and education.
Priority 2A – These weeds are common in isolated areas of Montana.  Management criteria will required eradication or containment where less abundant. Management shall be prioritized by local weed districts.
Priority 2B – These weeds are abundant in Montana and widespread in many counties.  Management criteria will require eradication or containment where less abundant. Management shall be prioritized by local weed districts.
Priority 3 – Regulated Plants – NOT Montana Listed Noxious Weeds. These regulated plants have the potential to have significant negative impacts. These plants may not be intentionally spread or sold other than as a contaminant in agricultural products. the state recommends research, education and prevention to minimize the spread of the regulated plant.
Download a copy of the current priority list of Montana Noxious Weeds.