Tri-Band Post Directed Spray application is not new. As early as 1960, the technique of dividing the chemical band into three separate bands and applying selective and non-selective herbicides accordingly, was practiced in the Mid South. At the time, DSMA was the only selective spray available for early row band application. Diuron was available for six inch cotton. These two selective herbicides were applied to the drill band and arsenic acid or dinitro to the shoulder area. Unfortunately none of these herbicides were labeled for post directed spray, consequently, little enthusiasm was generated for this application technique. With the advent of over-the-top herbicides there is now renewed interest in Tri-Band application. This interest stems from the desire to reduce weed control cost but more importantly, to improve weed control. Reducing weed control cost is a matter of narrowing band width and making early and precise applications. Improving weed control is a matter of applying the right chemical at the right time and using the right equipment. When using the right equipment, if the right chemical is applied at the right time, both reduced cost and improved control may be expected.

Other than seed placement, the word "precise" is not often used in describing field operations. For Tri-Band application, or for that matter any post directed band application, maintaining preciseness in the horizontal plane is important. Maintaining preciseness in the vertical plane is even more important. To be precise in the vertical plane requires that the nozzles be mounted on a very stable, free-floating, parallel linkage unit that is gauged from the shoulder area. To be precise in the horizontal plane requires a reliable guide system.

For a successful Tri-Band application program, a mechanical guidance system, a parallel acting applicator, and a dual spray system is the right equipment. The right time for the first application is two to three inch cotton and for the second application five to six inch cotton. The right chemical depends on specific weed problems.