Controlling weeds is an essential and expensive part of agriculture, and weed science studies all aspects of the problem: tillage systems, herbicide usage to control weeds, and weed control in such non-agricultural settings as along highways, railroads, golf courses and lawns, and irrigation and wetlands environments. This book is a major revision of our long popular basic textbook in weed science. The first part address fundamental principles of weed biology, management practices, herbicide selection and use. The second part, much revised in this edition, deals with herbicides grouped according to their functionality and physiological effect rather than their chemistry. The last part deals with practical use in specific situations: small grains, row crops, horticultural crops, lawns and turf, range land, brush, and aquatic weed control.