Droplet Size Increasingly Important for Sprayer Calibration

The discovery of soybean rust four years ago in the U.S. caused a surge in interest in sprayers and pesticide application technologies. And while that threat has not materialized in the Corn Belt as of yet, other less dramatic changes as well should be driving more careful consideration of how we apply water-based crop inputs.

These include:

• The nearly complete switch from soil-applied to foliar-applied herbicides in the past decade • Increase in fungicide applications for foliar diseases in corn • Explosion of rural residences within an hour’s drive of metropolitan areas

• Increasingly sensitive public in regards to environmental awareness

• Increases in input costs The proper calibration of a sprayer to achieve accurate, safe, and efficient application of crop protection products should be standard operating mode for any Top Farmer.

Using pressure, speed, and nozzle spacing, calibration steps are taken to ensure that the desired amount of spray material is being dispersed according to label recommendations. Most applicators are familiar with how to use flow rate charts from spray equipment catalogs and Web sites to determine the nozzle orifice size needed as described above. Applicators are also comfortable in making those applications with the benefit of an automatic rate controller to help improve the uniformity of application volume across the field. However, a sprayer calibrated in this manner does not guarantee the application will achieve its highest level of efficacy or minimize drift. That’s why we have invited Bob Wolf to this year’s Top Farmer Crop Workshop, who will present and offer hands-on advice during the Monday afternoon sessions at the Agronomy Farm.

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