Source: ForageFax
Now’s a good time to start your sprayer maintenance before the active spraying season begins. Tuning up your sprayer can better prepare you for accurate and effective herbicide applications. Any sprayer, old or new will perform better if you check it over before heading into the field.
The most common causes of inconsistent spray patterns are nozzle tips with different fan angles on the boom, uneven boom heights and clogged nozzles. Follow manufacturer recommendations to select nozzles for the best coverage. Make sure nozzles are clear of debris and residue. If a spray tip does clog, only use a soft bristled brush or toothpick to clean it. Since all nozzles wear over time, check the spray pattern and volume of each one. It’s easier to replace nozzles now as opposed to having to try and replace them the same day you are trying to make a herbicide application. Choosing the Right Nozzle to Reduce Spray Drift
Check the boom height to ensure proper spray overlap. The boom height should be based on the sprayer’s nozzle spacing. Check both 
the herbicide label and nozzle manufacturer’s recommendations to match herbicide application requirements with boom height and nozzle choice. Remember boom height can also increase the risk of herbicide drift onto non-target species.
Check your sprayer’s pressure. Consistent spray pressure creates consistent application rate, droplet size and spray pattern. If the pressure is too low, the spray pattern will not overlap, causing streaks. If the pressure is too high, drift potential increases. To obtain a uniform spray pattern and to minimize drift, keep the operating pressure within the recommended range for each nozzle tip.
Check for leaks, general wear and cracks in hoses, pumps and tanks! During the spraying season you cannot afford downtime. Check and restock your inventory of spare parts.
Sprayer calibration is a critical step in getting prepared for the spraying season. Sprayer Calibration ensures that the correct amount of pesticide is applied to the target site. Calibration is the process by which the amount of pesticide being applied per a unit of area is determined. This step is most often skipped because we get in a hurry, we calibrated it once a long time ago (surely nothing has changed) or we forget. By skipping sprayer calibration the applicator may be applying too much pesticide or not enough pesticide. If too little pesticide is applied, the pest may not be controlled. Using more product than label directions recommend is illegal, may not control the pest effectively, may injure non-targets and may be hazardous to the environment. For a step-by-step guide to calibrating a sprayer see the following publication: Sprayer Calibration
Last but not least, remember THE LABEL IS THE LAW! Refer to product labels prior to use and to ensure appropriate and safe use.
Dr. Vanessa Corriher-Olson, Ph.D., Forage Extension Specialist
Soil & Crop Sciences, Overton
Texas A&M AgriLife Extension Service