Weeds are considered one of the most serious threats to natural habitats and resources in the West. Noxious Weeds displace native plants and cause serious economic losses and environmental impacts. Noxious weed establishment reduces range and agricultural land productivity, reduces available forage for wildlife, and negatively impacts aesthetics and recreation. Ecological processes may be negatively affected by the invasion of noxious weeds; for example, Spotted Knapweed forms monocultures that can increase soil erosion. Spotted knapweed infests over 3.8 million acres in Montana, but there are new invaders that have the potential to do even greater ecological and economic damage, such as yellow starthistle.