ABSTRACT
Weeds are a major constraint to the realization of optimum yield in agricultural systems. 1 Unwanted plant species reduce efficiency of plant establishment in range and forestry systems as well. 2 , 3 Synthetic chemical herbicides account for approximately 60 to 70% of all the pesticides used on cropland. 4 , 5 Agricultural practices, such as weed control with synthetic chemical herbicides, are a major cause of nonpoint source surface and ground water pollution. 4 The increased use of pesticides has intensified concern and public debate on public health and environmental consequences of current agricultural practices. Synthetic herbicides are coming under fire as contributors to problems of ground water pollution, 6 herbicide persistence, 7 and weed resistance. 8 As the public becomes more aware and concerned about pesticide residues in surface water, groundwater, and food, stricter herbicide regulations will be handed down; fewer pesticides will be released for use; and many of the pesticides presently on the market may be withdrawn. As a result, weed management strategies will be forced to rely less on synthetic chemical pesticides and more on cultural and biological methods. 9
