Emerging weed problems in the West include sulfur cinquefoil, squarrose knapweed, perennial pepperweed, and dyers woad. In Montana spotted knapweed increased from a few plants in 1920 to 5 million acres today. In Idaho rush skeletonweed increased from a few plants in 1954 to 4 million acres today. In northern California yellow starthistle increased from 1 million acres in 1981 to 10 million acres today. Ecological Damage Garlic Mustard Weeds are destroying wildlife habitat and forage.
Wildlife needs a variety of forage to thrive.
Unfortunately, because of aggressive growing habits, invasive weeds often outcompete native plants, replacing plant diversity with sometimes poisonous monocultures. Weeds are damaging endangered species and native plants . Weeds are increasing soil erosion. This damages vital streams that provide habitat for fish, including threatened and endangered species such as salmon. Weeds are increasing groundwater loss.