Explains how simple and creeping perennial weeds reproduce and spread. Covers weed seedbanks, seed dormancy in soil, and factors that influence seed germination. Describes the typical root structure of perennial weeds and the various ways perennial weeds compete with crop plants for water, nutrients, and light. Discusses the advantages and disadvantages of various methods to control perennial weeds, such as prevention, mechanical control, herbicide applications, and biological control. Includes sources for additional information.