I agree with Gene. Each herbicide has specific instruction sheets for calibrating one's spray rig based on dilution, traveling speed, pump speed and delivery and other factors, including nozzle output, condition of the nozzles, pump, etc. When in doubt go by pesticide label instructions and follow exactly as possible. [Also, with any pesticide, consider wind factors, potential drift, temperature factors, and your legal liability should a herbicide or other pesticide damage a neighbor's crops or animals].