The classical definition of a weed is: a plant growing out of place or growing where it is not desired. According to the Weed Science Society of America, the currently accepted definition is: any plant that is objectionable or interferes with the activities or welfare of man. Within the context of a turfgrass community, the definition can be expanded to: an undesirable plant because of its negative impact on the esthetic appearance, soil stabilizing capacity, or overall utility of a turf.

The control of weeds in turfgrass communities may include virtually any practice designed to prevent weed emergence or to effect shifts toward desirable turfgrasses and away from undesirable vegetation. Historically, turfgrass weed control has been heavily dependent upon properly establishing well adapted turfgrasses and creating an environment conducive to their healthy, vigorous growth. As the components of a strategy for resisting weed invasion generally correspond to measures for achieving and maintaining acceptable turf quality, cultural control of turf weeds has generally been synonymous with proper turfgrass culture. Because managing weeds usually involves a combination of chemical and cultural methods, it should be based on a knowledge of the specific weeds to be controlled, the habitats in which they are likely to occur and the means by which they enter and persist in a turfgrass community. This information is covered in the three chapters on weed taxonomy, ecology, and control; and constitutes the foundation on which a turf weed control program should be constructed.
About the Author:

Stephen H. Anderson is the William A. Albrecht Distinguished Professor of Soil and Environmental Sciences in the Department of Soil, Environmental, and Atmospheric Sciences at the University of Missouri in Columbia, MO. Current areas of research in his program include evaluation of soil management effects on soil hydraulic properties, development of X-ray computed tomography and microtomography techniques for assessment of pore-scale soil properties and processes, and utilizing hydrologic models to evaluate effectiveness of conservation practices at the watershed scale. He teaches courses in pollutant fate and transport, environmental soil physics, watershed modeling using GIS, and vadose zone transport.

Jan W. Hopmans is Professor of Vadose Zone Hydrology in the Department of Land, Air, and Water Resources and Associate Dean in the College of Agricultural and Environmental Sciences at the University of California in Davis, CA. Current areas of research in his program include development of experimental and mathematical methods to better understand the fundamental processes controlling soil water flow and chemical transport and include interests in plant root-soil water interactions, parameter optimization, regional irrigation water management, soil moisture sensor development, soil salinity, and climate change impacts on California's hydrology. He teaches courses in soil physics and vadose zone modeling.