This law requires a landowner to control the spread of the plant or prevent any seed production by the plant. Because purple loosestrife grows so aggressively, over time large stands of the plant take over an area and replace the native plant species. This results in eliminating the natural foods and cover essential to many wetland inhabitants including waterfowl. In addition, purple loosestrife can grow in and around irrigation systems and impede the flow of water. The Winchester wasteway, an irrigation system in Grant County, Washington, is reported to have one of the largest stands of purple loosestrife in the country.
Purple loosestrife is a cause for grave concern among water users and purveyors.
No native herbivores or pathogens in North America are known to suppress purple loosestrife. Current means of plant control include mechanical cutting or application of herbicides. Exciting research into using biological controls on purple loosestrife is currently being conducted. These efforts are focused on using insects from the plant s native range in Europe. The root-mining weevil lays eggs into the stem of the plant and the developing larvae work their way down into the roots.