Four distinct pest management strategies are generally recognized by specialists: avoidance, prevention, suppression, and eradication. Avoiding awed population may be possible under certain circumstances, such as using crop rotation to avoid a particular weed problem, or planting the crop aftermost weeds of a particular species have germinated. However, this strategy is very limited with weeds since almost all fields are infested with a potentially economically damaging level of weed seeds. Prevention, simply stated, means not allowing a weed population to become established in a field. This is a lofty goal because of the propensity of weed seeds to spread from place to place. However, prevention should be an underlying strategy with every grower and practiced when feasible as a general sanitation measure. Suppression is the strategy employed by essentially all growers in an effort to produce their crop while keeping weed populations below an economically damaging level. It is this strategy that should receive most attention with respect to choosing and placing into practice the tactics for carrying out the plan: Eradication has very limited usefulness to most growers, since it is practically impossible except on small, isolated weed infestations.