Why is there a need to control noxious weeds? Noxious weeds are plants that typically invade from other countries, leaving their natural controls and competitors behind (insects, diseases, grazers, and climate). The resulting uncontrolled growth of these weeds crowds out native plants and animals, and causes serious damage to our environment and present way of life. Five methods are currently being used to control the spread of invasive noxious weeds. They are: preventive and cultural (indirect control methods), and chemical, mechanical, and biological (direct control methods). In most cases, one form of control is not enough. Control often requires the combined efforts of two or more "integrated" methods to effectively stop the spread of weeds.

           The control of noxious weeds is a complex battle, with a number of factors governing the methods that may be used. First, they must be safe for humans, the environment, and non-target plants and animals in the area. Second, they must effectively reduce the targeted weed population. Third, effective control practices depend on the life cycle of the weed, the location, and the size and density of the population. Controlling the patch of annual weeds in the vacant lot next door is very different from treating a 1000 acre perennial weed population located in the mountains. Fourth, the availability, or lack of tools and other resources may prevent some control options. And fifth, what is the desired end result? You can eradicate the population, reduce the population in size and density, contain them and prevent them from invading new areas, and/or let the weeds grow uncontrolled.