Nozzle height in relation to speed is critical in obtaining uniform application. Nozzles 4 to 5 ft off the ground are subject to wind and speed distortions. The nozzle pattern width is decreased 15 to 20 percent by traveling at speeds of 12 mph. Patterns are more distorted as speed increases. Bear in mind that traveling 10 mph into a 6 mph head wind results in a 16 mph wind speed at the nozzle.
High speeds can also create a vortex behind the sprayer, thus further distorting the pattern.
The travel speed must be selected according to field conditions to obtain uniform application and to keep the boom from whipping back and forth or bouncing up and down. Bouncing and whipping of the boom will cause skips in weed control patterns. For most applications, the maximum travel speed should be 12 mph rather than the speeds of 18 to 22 mph that are often used. Also, higher speeds create more dust which may reduce the effectiveness of paraquat. Dust flaps mounted on the sprayer behind the wheels help to reduce dust but may increase vortex problems.