Modern weed science combines basic and applied sciences in the study of weeds, typically defined as plants that are objectionable or interfere with the activities or welfare of humans. Although weeds have been associated with human activity since the beginning of crop cultivation, the history of weed science parallels the history of modern day agriculture and is less than 100 yr old. From an early emphasis on chemical weed control, the field of weed science now integrates preventive, mechanical, chemical, cultural, and biological tactics in the management of weeds. Weeds cause tremendous economic costs to agriculture and natural resources in terms of crop loss, loss of land utility, health-related problems, and the costs of control. Weed science is now expanding its focus to include invasive plants in natural systems, which are undesirable from an ecological perspective rather than just an economic one.

Additional index words: Integrated weed management, invasive plants.

Abbreviations: IWC, integrated weed control; WSSA, Weed Science Society of America.