It will be spraying season before we know it, so now is a good time to get your sprayer ready to go. Why, you ask? Let's assume you are 10 percent off on your application rate and spraying a $10/acre chemical on 100 acres. That could equal $100 total in over-application, or even worse, poor pest control.
I hope you took the time to properly clean and winterize your sprayer last fall. If not, you may have some cleaning and repairs to do. Start by rinsing the tank out. Hopefully, you have a drain or filter you can open between the tank and the pump. If you don't have a filter between the tank and the pump, now would be a good time to install one. It will make cleaning the tank easier and extend the life of your pump.
If you have a boom sprayer and you didn't do so last fall, take out all the tips and screens, clean them with a soft brush and look for visible damage. Now fill the tank about one third full with fresh water and start the pump and sprayer. Hopefully, you can get enough pressure to run some water through each nozzle body to clear the lines.
Before putting the tips and screens back in, be sure they are all the same size and type and are not damaged. If you could not get water through all the nozzle bodies due to lack of pressure, start replacing the tips and filters in the middle of a line and work your way to the ends as most debris will be flushed to the ends.
Now you can pressure up your sprayer and look for leaks. Be sure to inspect hoses, connectors, fittings and anywhere else you can think of. Look for hoses that may have kinked in the past, correct the problem and replace the hose.
With the sprayer running, collect the output from each tip for one minute, measure and record. Calculate the average across the boom. If any tip deviates more than 10 percent from the average, replace it.
Finally, we (and by we, I mean you) are ready to calibrate your sprayer. Measure the distance between spray tips. From the table, drive the appropriate distance and measure the amount of time it takes to drive that distance. Drive the length three times in the gear and RPM that you normally spray at and calculate the average time. Be sure to note the RPM.
Now park the sprayer on a secure surface. Turn the sprayer on at the same RPM you used on the test course. Collect the output from a nozzle for the amount of time it took to drive the course. Measure the output in ounces and repeat three times. Find the average of the ounces, and this is your gallons per acre.
This information is very important when determining how much water and chemical to put in the tank to spray a given area.
A boomless sprayer is a little different but similar. We have stickers that you can affix directly to your sprayer that outline these processes (Noble Research Institute publications NF-SO-03-03 (boom or boomless)). They can be obtained by contacting Ag Services and Resource at (580) 224-6480. Be sure to specify boom or boomless.
As always, be sure to wear the appropriate personal protective equipment when working with pesticides and pesticide application equipment.
For more information contact the Noble Research Institute Helpline at (580) 224-6500.