The most common failures of sprays fall into this category. Spray nozzles may get clogged, or just worn down over time and often need cleaning or replacing. It is important to check every time a spray application is made. New spray tips will produce uniform distribution when properly set up. These sprays are so precisely manufactured that even small amounts of dirt or residue can affect the output of the spray nozzle. The tips may also just get worn, or rounded, over time and these worn spray tips typically produce a higher output of spray material, which results in uneven spraying, higher spray concentration in some rows, and errors in mixing and rate calculations. Spray tips may also be physically damaged which often results in erratic sprays, sometimes over or under-applying. See picture below:

Using filters and adequate strainers can help prevent clogging at the spray tips, but if clogging does occur- tips can be cleaned with light brushing, or just replaced altogether. It is a good practice to run clear water through the entire system, from the tank through the spray tips. Some materials (such as surfactants) may not completely wash out with just water and will need special cleanings agents to fully clean equipment. Pesticide labels will usually include special instructions, if needed, for cleaning equipment and these should be carefully followed when present.

2. Test (and Adjust) Your Speed

Speed of your tractor ( or any other spray implementation) can have a large effect on spray coverage and efficacy. Typically, faster spray speeds will necessitate larger spray volumes (gallons per acre) in order to compensate for decrease in spray coverage associated with increased speeds. In established orchards, slower speeds may be needed in order to reach upper canopy of the trees that could be missed. Surveyors tape attached to a pvc pipe, extended to the upper portion of the orchard canopy, can be used to monitor air movement. This simple tool can be used to monitor whether tractor speed and spray fan are adequate in achieving full coverage.

3. Know Your Nozzle / Droplet Size

Selecting the correct nozzle is based on desire droplet size. Droplet size can play a large role in efficacy of a particular pesticide product, and play a huge role in determining drift. Nozzles used in agriculture fall into the following categories: fine, medium, coarse, or very coarse droplets. Different pesticides and herbicides will have different optimal droplet sizes, depending on modes of action (systemic or contact) and coverage needed for maximum efficacy.

The droplet size is determined by nozzle type and pressure. The example guide below is from TeeJeet nozzles but all nozzle manufacturers will provide this information.