Herbicide technology and use have been the focus of weed management research for the past several decades. Herbicides are an important component of weed management and will remain so for years to come. However, there is increasing pressure to improve the efficiency of herbicide use and develop alternative control methods. Herbicides are used on over 95% of the com and soybean in the Com Belt because of the presence of weeds and the need to minimize their adverse economic impacts. Large inputs of herbicides and tillage are needed to control weeds because of the lack of knowledge of weed biology and ecology, continuous production of summer annual row crops, and the absence of control alternatives. Currently, weed science has few, if any, alternatives to herbicides and tillage that are both economically and environmentally desirable.