Farm sprayer “tune up”

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

With the possibility of Asian soybean rust coming to Michigan this summer, and with the very likely probability of soybean aphids returning, early April may be the best time to “tune up” your farm sprayer. Insecticide and fungicide spraying will require more thorough leaf coverage and deeper into the foliage than glyphosate or most other herbicide sprays.

A ground-based, farm field crop sprayer needs to be calibrated at least once per growing season to be sure that it is in good working order and that the nozzles are applying the proper flow rate. With a sprayer in good working order, a tank that is half full of water, and knowing the proper nozzle flow rate, calibration should take about an hour or less.

The two primary things to check are the tractor ground speed and nozzle flow rate. I usually set up a 200-foot course, ideally in the field, to check ground speed of the equipment once as it goes down the course and then again coming back. Pulling the sprayer with a tank half full of water will give an approximation of average travel conditions. Remember to write down the gear and the engine rpm setting for actual spraying.

Then with the tractor parked and the engine running at the ground speed rpm setting, turn on all the spray booms. Before this, I replace the outside nozzle of one boom with an oil filled pressure gauge. The pressure at the boom is the actual operating spray pressure, regardless of what the gauge in the tractor or by the sprayer controls reads. With the sprayer operating at the proper pressure, now you can check the nozzle flow rate of the other nozzles on that boom and compare this amount to the nozzle company reference book. Repeat this process with all the sprayer booms.

MSU Extension
has a free calibration sticker, AM-53, that can be affixed to the sprayer to help the farmer with one simple nozzle calibration procedure. Extension also has bulletins dealing with sprayer calibration, and the Pesticide Core Training manual, E-2195, has some excellent calibration information.

Remember to write down the sprayer calibration date for Michigan Right-to-Farm record keeping. Right-to-Farm also suggests that farmers have a portable spill kit available and a portable mix-load pad if they are mixing and loading pesticides in the field. Write down all the weather conditions when spraying to help you recall the wind direction and speed in case of a drift complaint.

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