Tips to minimize spray drift

Courtesy of Agriculture and Natural Resources, Univ. of California

Although spray drift is something that will be a constant when it comes to liquid application, it is a problem well within the realm of making more efficient applications. Controlling spray drift not only saves the environment, but can save your pocketbook from retaining precious herbicide.

"Spray drift needs to be minimized to avoid any crop injury and adverse effects on areas outside the spray target area," said Dallas Peterson, Department of Agronomy professor at Kansas State University. "Minimizing spray drift is not only important from and economic and legal standpoint, but also from a public relations standpoint."

Here are some simple tips to keep in mind before heading out into the field:

Wind Speed

"There is no absolute right answer to the question regarding when is it too windy to spray. Labels will provide maximum wind speeds that can't be exceeded to remain in compliance with the label. However, it still may be too windy to safely spray at lower wind speeds if a highly susceptible crops is downwind of the application," said Peterson. "In that situation, the only safe time to spray is when the weed is in the opposite direction. Common sense has to be a major factor in determining when and where it is safe to spray to avoid herbicide drift problems."

Spray Pressure and Spray Speed

The smaller the droplet, the greater odds of creating drift. In addition, smaller droplets are created by higher spray pressures. Pressure shouldn't exceed 40 psi.

"The appropriate spray pressure is critical to produce a good spray pattern and droplet size," said Peterson. Increasing spray pressure reduces spray droplet size and increases the number of fine spray droplet particles that are most susceptible to spray drift. The appropriate spray pressure to optimize performance and minimize drift will depend on the type of spray tip being utilized."

Booms and Nozzles

Position the booms as close to the crop canopy to ensure application reaches the ground. Nozzle tips and pressure is determined by the individual herbicide. Read the label of each chemical to learn proper resistance specifications.

"Spray nozzle selection can have a big impact on the potential for spray drift because of the effect on spray droplet size and spectrum," said Peterson.

Droplet Size

Small microns, 100 to 200 for example, will create a greater risk of spray drift. Larger droplets won't be a susceptible to drift.

"Smaller spray droplets are more susceptible to movement by wind, especially the very fine droplets that can stay suspended longer and moved longer distances," said Peterson.