Scotch broom , Parrotfeather , Tansy ragwort, Spotted knapweed, Lawnweed, Meadow knapweed, Eurasian watermilfoil, Leafy spurge, Brazilian elodea, Diffuse knapweed, Velvetleaf and Yellow nutsedge. Prohibited Plants and Seeds in Washington State Weed Prevention Effective weed control is seldom accomplished by using a single control method. Prevention, reducing the threat of one or more weed species from occupying an area, is a strategy that should always be a part of an overall weed management plan. To have a successful prevention plan, the land manager must combine early detection of weeds along with other measures to reduce conditions, which allow for the continued spread of invasive weeds. A simple measure a land manger can implement to prevent the invasion of weeds to a site is prohibiting the introduction of weed seed from contaminated crop seed, livestock feed and machinery.
Prevention is the most practical means of controlling weeds.
Take the time to scout for new weeds, identify them and control small infestations. Communicate and work cooperatively with neighbors about weed control areas. Embrace a land stewardship ethic. Implement land management practices that maintains and optimizes competitive crops and native habitat. Create and maintain clean boundary areas that can be monitored to prevent the encroachment of new weeds.