CropWatch April 2, 2010: Pesticide Label Changes Affect Sprayer Set-up and Calibration

CropWatch April 2, 2010: Pesticide Label Changes Affect Sprayer Set-up and Calibration

April 2, 2010

This spring you'll notice a change on pesticide labels that may warrant a change in how you apply pesticides. New label statements on spray particle size address how to improve the pesticide efficacy and spray drift management — two key factors of pesticide application. These label changes will mean additional requirements for sprayer calibration affecting nozzle selection, pesticide preparation, and spray volume.

Label Changes

Carrier Amount. Many pesticide labels now include statements such as “Use a minimum of 15 gallons per acre spray volume for best performance.” or “Herbicide should be applied broadcast in a minimum of 15 gallons of water per acre. Under dense weed canopies, 20 to 40 gallons of water per acre should be used so that thorough spray coverage will be obtained.” These statements on amounts are concerned with the efficacy of the pesticide.

Spray Drift. The other item in pesticide application is spray drift management, also noted as DRT ― Drift Reduction Technology. Spray drift management includes many factors besides spray particle size such as wind speed, boom height, distance to susceptible vegetation, relative humidity, temperature and temperature inversions.

Many pesticide labels now include statements such as, “Use nozzles and pressures that generate medium (about 250-350 microns) spray droplets category as reported by the nozzle manufacturer and in accordance to ASAE 572." Some may even go on to say, “Do not use pressures that result in coarse sprays and that fine sprays should be avoided to minimize spray drift.” These statements on spray particle size address how to improve pesticide efficacy and spray drift management — the two items we are concerned with in pesticide application.

ASAE Standard 572.1 covers spray nozzle classification by droplet size to indicate potential for off-site spray drift and application efficacy.

"This Standard defines a means for relative nozzle comparisons only based on droplet size."

Approved as an American National Standard March 2009

The modified standard (ANSI/ASAES572.1, March 2009) adds classification categories for “extremely fine” and “ultra coarse” droplets. With the new requirements, the first step in sprayer calibration is selection of the type of spray nozzle tip, size, and pressure to provide the spray particle size and spray volume specified on the pesticide label.

Also see Calibrating Your Sprayer to Provide Effective, Consistent Control in this week's CropWatch for information on factors affecting sprayer application consistency and how to calibrate your sprayer.

Robert Klein
Western Nebraska Crops Specialist