3 3 Es of Pesticide Application Application Goals3 Es of Pesticide ApplicationEffectiveEfficientEnvironmentalNorman Morgan22
4 Airborne movement of droplets or vapours from the treated area Spray DriftAirborne movement of droplets or vapours from the treated areaDroplet drift usually occurs within minutes of the application, vapour drift can occur minutes or days after application
5 On-Swath DepositLow boom Slow speedHigh boom Fast speed
22 Droplet Size Distributions Let’s talk about how we describe droplet size. Here is a typical distribution of spray volume in an agricultural spray, using a conventional nozzle (red). Note that the spray contains both very small (10 µm) and very large (1000 µm) droplets. The majority of the spray volume is in intermediate sized droplets between 200 and 500 µmWhen we lower the pressure (or change to a low-drift nozzle), we still retain the same large span of droplet diameters ranging from 10 to 1000 µm (blue bars). But now, the distribution has shifted to the right. This means less volume in small droplets (less drift), more volume in large droplets. The majority of the dose remains in the middle region, but more of it is in the larger droplets. As long as we don’t go too far with coarseness, we’re OK.All low-drift nozzles operate on the same basic principle (internal pressure drop creating larger droplets).22
35 Droplet Velocity Distributions Spray velocity tends to slow down with coarser sprays, due to the lower internal pressures of these nozzles. This means that large drops from a low-drift nozzle are more easily retained than the large drops from conventional nozzles – a good thing.35
61 Inversion Conditions Dispersion Spray cloud disperses, moving upward and downwindUnstable (Desirable normal daytime conditions)Warm SoilInversion ConditionsDisapppears after sunrise and 2-3 degree increase in temperature.Warm, still airSpray cloud hangs over treated area in high concentrationStable (inversion)Cold air - dense, stillCold soil
70 Wind Calm conditions not well suited for spraying unpredictable wind directionsometimes mistaken for inversionsLow, steady winds idealPredictable directionDilution of spray cloudHigh winds increase total loss, but do not always increase deposits
Your consent to our cookies if you continue to use this website.