Category III & IV

Category III


Category III noxious weeds have not been detected in the state or may be found only in small, scattered, localized infestations. Management criteria include 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.

Noxious Weed Species Common Name Scientific Name
Yellow Starthistle Centaurea solstitialis
Common Crupina Crupina vulgaris
Eurasian Watermilfoil Myriophyllum spicatum
Dyer's Woad Isatis tinctoria
Flowering Rush Butomus umbellatus
Japanese Knotweed Complex Polygonum cuspidatum, sachalinense and polystachyum

Category IV


Category IV noxious weeds are invasive plants and may cause significant economic or environmental impacts if allowed to become established in Montana. Management criteria include prohibition from sale by the nursery trade. Research and monitoring may result in the plant being listed in a different category.
Noxious Weed Species Common Name
Scientific Name
Scotch Broom
Cytisus Scoparius