Tips for Effective and Safe Spraying Crop Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest. To control pesticides, we can use sprayer machinery, as like as agricultural aircraft sprayer and blower sprayer. Spraying pesticides on fields is one of those jobs where the margin for error is pretty narrow, both in terms of accomplishing the mission and protecting neighboring fields. 10 tips for more effective and safe spraying from Mark Hanna, i.e.:

The first of effective and safe spraying is small drops take time to hit target.

The first step in sprayer calibration is to determine the correct nozzle type and size (flow rate). Flat-fan nozzles are used for broadcast spraying of most herbicides and some insecticides where a medium droplet size is needed. Flat-fan nozzles are used for banding herbicides. Flooding type and full cone nozzles used for pre-plant herbicides produce drift-resistant large droplets, and wide nozzle spacing can be used. Hollow cone nozzles produce smaller droplets and are used to apply insecticides and contact herbicides that need to penetrate the canopy.

A tiny droplet 100 microns in diameter (about the diameter of a human hair) takes 11 seconds to fall 10 feet. At 50 microns, it takes 40 seconds to fall that far, because of the drag that air friction puts on them. That's a long time for a wind current to move that droplet to an unintended target. Most spraying machines still break up spray liquid by squirting it under pressure through a hole - commonly referred to as anClose-up of hydraulic nozzle detailing variation in droplet size.

The second of effective and safe spraying is Droplet size depends on pressure.
As sprayer pressure increases, droplets get smaller. Decrease pressure and they get larger. Change the pressure as you go through a field, and droplet size changes, too. That changes how the spray material moves in air, and may increase the likelihood of spray drift.

This explains why it's good practice to slow down when you spray near neighbors' gardens or crops. As you slow down and the controller reduces nozzle pressure, droplets grow larger and are less likely to drift.

The third of effective and safe spraying is small droplets dry quickly.

That’s particularly true during warmer temperatures that commonly occur during post-emergence applications. The water in a droplet under 150 microns in size can evaporate in a few seconds in the right conditions. Wind can then easily move the chemical residue, creating a drift issue.

In contrast, it takes two to three minutes for a bigger droplet to evaporate, meaning it reaches the target before significant water loss occurs.

The fourth of effective and safe spraying is Nozzles produce variety of nozzle sizes.

Nozzle size depends on the desired application rate, ground speed and nozzle spacing. For each nozzle type and spray angle, the manufacturer recommends spray height and nozzle spacing. Nozzle spacings of 20 and 30 inches are most common. The desired flow rate from the nozzle can be determined from the following equation:
GPM = (GPA x MPH x w) / 5940
GPM = the nozzle flow rate in gallons per minute,
GPA = the application rate in gallons per acre,
MPH = the ground speed of the sprayer in miles per hour (MPH = (ft/min) / 88), and
 w = the nozzle spacing in inches for broadcast spraying.
Nozzles are used for three purposes: to distribute a liquid over an area, to increase liquid surface area, and create impact force on a solid surface. A wide variety of spray nozzle applications use a number of spray characteristics to describe the spray. Your sprayer nozzles may be identical, but droplet sizes are not. Each nozzle produces a range of droplet sizes. If you spray a medium droplet of 225 to 325 microns, 5%-10% may be fine droplets of 150 microns or less, and 5%-10% may be large droplets of 450 microns or more. Those small ones are the most likely to drift off target.

The fifth of effective and safe spraying is Weather impacts spray drift.

Spray drift as the physical movement of a pesticide through air at the time of application or soon thereafter, to any site other than that intended for application (often referred to as off-target). Drift is greater at warmer temperatures, and is greatly impacted by boom height. "At a warm temperature like mid-80 degrees, a 10 miles per hour (mph) wind can create spray drift distance similar to a 15 mph wind at 50 degrees," says Hanna. And, a boom height of one to two feet above the crop canopy will usually have little drift. But at three feet, drift distance goes up significantly. Off-target spray can affect human health and the environment. For example, spray drift can result in pesticide exposures to farm workers, children playing outside, and wildlife and its habitat. Drift can also contaminate a home garden or another farmer's crops, causing illegal pesticide residues and/or plant damage. The proximity of individuals and sensitive sites to the pesticide application, the amounts of pesticide drift, and toxicity of the pesticide are important factors in determining the potential impacts from drift.

The sixth of effective and safe spraying remember coverage and efficacy.

Increase droplet size to reduce spray drift, but remember to consider spray product coverage and efficacy. To get the spray on the target area, and larger droplets can reduce your ability to do that. Here's why: If the droplet size is 400 microns and you are spraying 15 gallons of product per acre, it's putting out about 270 drops per square inch. This is often adequate for systemic pesticides (the kind that travel or translocate within the plant). Reducing droplet size to 300 microns (at 15 gallons per acre) increases coverage to 640 drops per square inch. The extra drops per square inch can improve performance of a contact pesticide.

The seventh of effective and safe spraying is Read the label.

Droplet size doesn't seem to impact it; fine, medium, and coarse droplets achieve about the same coverage. Medium size might win in that case. A good starting point is probably 250 micron droplets for all classes of sprays. In fact, he continues, some newer pesticides put that right on the product label - 250 to 350 microns, along with a desired application rate such as 15 gallons per acre.

The eigth of effective and safe spraying is Venturi nozzles balance efficacy and drift.

The newer Venturi-style nozzles offer an advantage to older styles: You can get larger droplet size at a given pressure. There's a small hole on the Venturi nozzles that draws air into the liquid flow. This can produce air bubbles in the spray stream, giving larger droplets and less potential for drift in some circumstances. Newer styles of Venturi nozzles operate at lower pressures, and although droplet size is slightly smaller than older Venturi styles, they may help maintain a balance between efficacy and drift, depending on application needs.
The ninth of effective and safe spraying is Manage rate controllers.

This will help you maintain consistent coverage. In some cases, you may double spraying speed from 6 mph to 12 mph. To apply the same spray volume, you have to double the flow rate because you're covering twice as much ground. You have to increase pressure by a factor of four to produce that volume.