There has been a lot of research focusing on spray rig speed and spray coverage. Work by Jack Dibble back in the 70s-90s indicated that the best coverage is achieved at 1.5 MPH, and was the basis of the compromised recommendation of 2.0 MPH. This work has since been repeated by Dr. Joel Siegel (along with several collaborators) and Dr. Ken Giles and colleagues at Arbuckle, CA, and has indicated that at higher speeds, control of navel orangeworm (NOW) is lost in the upper canopy of the tree (>15′ high). This, interestingly enough, is where the majority of the crop is located. A few articles have been posted on this in the past (Speed Doesn’t Kill, Speed Doesn’t Kill, part 2).