HE efficiency of cotton production has been materially increased T since 1949 through the use of several preand post-emergence herbicides (2, 4, 5, 6, 10, 14, 17, 18, 19). In the high-rainfall areas, combinations of a pre-emergence herbicide such as isopropyl N-(3-chlorophenyl)carbamate (CIPC) or 3-(3,4-dichlorophenyl)-l, l-dimethylurea (diuron) with one of several post-emergence oils have given more dependable control than the use of single herbicides. In the irrigated areas, early-season weeds have been less of a problem and more attention has been given to herbicides for the control of late-appearing grasses and vines. The substituted ureas, 3-(p-chlorophenyl)-l, l-dimethylurea (monuron) and diuron, have been the most successful herbicides for this use. The initial effectiveness of currently recommended pre-emergence herbicides is greatly influenced by surface moisture. They do not normally provide more than 6 weeks of control, do not always control all susceptible weeds, and their effectiveness is reduced or lost in the event the crop has to be replanted. The herbicidal oils used in the high-rainfall areas are difficult to use, should not be used on older stages of cotton, and have no residual effect. Post-emergence applications of diuron and monuron depend on adequate surface moisture for effectiveness and have relatively little effect on emerged weeds. Thus, despite considerable progress there still remains a real need across the entire Cotton Belt for an effective, economical, and easy-to-use post-emergence herbicide. Such a herbicide should kill seedling and established weeds and prevent the development of weeds from seed in the soil. Numerous workers have reported promising results with several herbicides, but with the exception of certain lay-by treatments, none of the evaluated treatments have been put into practical use. Expense of the treatments, lack of sufficient selectivity, failure of the treatments to control both ungerminated and established weeds, and dependence of the treatments on soil moisture have prevented general acceptance of the herbicides. The study reported in this paper was conducted in an attempt to develop weedcontrol methods that would avoid or minimize some of the problems listed. It has been primarily a field study with a limited amount of supporting greenhouse work.