Spray Drift Reduction Practices John Nowatzki Extension Ag Machine Systems Specialist

Spray Drift Reduction Practices How Pesticides Drift Climate Conditions Droplet Size Drift Control Additives

How Pesticides Drift Vapor Drift - Pesticide molecules volatilize (evaporate) and move as a vapor. Particle Drift - Spray droplets - formed during application. Droplet size Equipment and method of application Wind speed Other climatic conditions.

Climate Conditions - Wind Lowering booms reduces time for droplets to reach the target Influence of droplet size on potential distance of drift Droplet diameter (microns) Type of dropletTime required to fall 10 feet Droplets travel while falling 10’ in a 3 mph wind 5Fog66 minutes3 miles 20Very fine spray4.2 minutes1,100 feet 100Fine spray10 seconds44 feet 240Medium spray6 seconds28 feet 400Coarse spray2 seconds8.5 feet 1,000Fine rain1 second4.7 feet

Climate Conditions Temperature Inversions Temperature Near the Surface is Cooler than Above. Measure Temperatures Near the Surface and 10’ Higher. Fog areas without standing water - temperature inversion.

Climate Conditions Measuring Temperature Inversions Temperature Near the Surface is Cooler than Above. Measure Temperatures Near the Surface and 10’ Higher. Temperature Sensor Readout

John Enz, Vern Hofman, Andrew Thostenson NDSU Extension Publication

Droplet Size and Drift Influence of droplet size on potential distance of drift Droplet diameter (microns) Type of dropletTime required to fall 10 feet Droplets travel while falling 10’ in a 3 mph wind 5Fog66 minutes3 miles 20Very fine spray4.2 minutes1,100 feet 100Fine spray10 seconds44 feet 240Medium spray6 seconds28 feet 400Coarse spray2 seconds8.5 feet 1,000Fine rain1 second4.7 feet

Selecting Drift-reducing Nozzles Half of spray volume is of smaller droplets Half of spray volume is of larger droplets

Selecting Drift-reducing Nozzles Conventional Flat Fan Larger Orifice Lower Pressure

Selecting Drift-reducing Nozzles Pressure-reducing Chamber Nozzles Uniform Droplets over Wide Pressure Range

Selecting Drift-reducing Nozzles Air Induction Nozzles Metering Orifice Spray Orifice Fewer Fine Droplets

Selecting Drift-reducing Nozzles Variable Flow Rate Nozzles Flexible Orifice Changes in Response to Pressure Changes Maintains Pattern and Droplet Size

Selecting Drift-reducing Nozzles Pulse Modulation Sprayers Independent Nozzle Pressure Control Maintain Rate and Droplets

Drift Control Additives Spray Patterns Droplets Deposition Properties Uptake and Penetration

Drift Control Additives Water Conditioners Prevent Pesticides from Bonding to Mg and Ca ions Ammonium Sulfate (AMS) Dipotassium phosphate

Drift Control Additives Surfactants (Wetter-spreaders) Lower Surface Tensions Nonionic Surfactants (NIS) Organosilicones

Drift Control Additives Oil Concentrates Soften Waxy Leaf Surfaces Petroleum Oil Crop Seed Oil

Drift Control Additives Evaporation Retardants Slow Water Evaporation Opposite of a Desiccant. Petroleum Oil Crop Seed Oil

Drift Control Additives Drift Suppressing Agents Increase Viscosity Improve Retention Reduce Small Droplets

Spray Drift Reduction Practices Know your surroundings Sensitive Crops Surface waters Honey Bees Climate Conditions Wind Temperature Inversions Droplet Size Use as coarse a spray as possible Use Drift Control Additives Dicamba/2,4-D formulations

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