When you pull the sprayer into fields each spring, you’re banking that the product coming out of the nozzles will land where you need it to work. That’s where drift reduction adjuvants (DRAs) can become one of the most profitable—and protective—ingredients in your tank.
Consider what happens when you spray a crop protection product. Each nozzle throws out a spectrum of droplet sizes, from big “marbles” that fall quickly to tiny “dust” droplets that hang in the air, explained Greg Dahl, director of adjuvant education for the Council of Producers & Distributors of Agrotechnology (CPDA), during a recent Agricultural Retailers Association webinar.
Those tiny droplets, called driftable fines, are the troublemakers. They lose energy fast, ride the wind and can move well beyond your field. That’s not the case for larger droplets.
“Big droplets have to land. They are going to land, and they’re going to land close to where you spray,” Dahl says. “Small droplets, they probably are not going to land. They will lose their speed, and then they’ll just float in the air and go wherever the air goes.”
By design, DRAs shift more of your spray volume into larger, heavier droplets that are still effective but far less likely to drift. Across a wide range of nozzles, Dahl says industry research shows that adding a DRA can reduce the spray volume made up of driftable fines.
“Going across the whole system of nozzles, we get about a 50% reduction in the amount of spray volume that is made up of driftable fines,” he reports.
In practical terms, that means less product left hanging in the air and able to drift toward your neighbor’s crops, garden or yard.
Drift Control Is Only Part Of The Benefit From DRAs
Many farmers are concerned that bigger droplets going out of the nozzles will automatically result in poorer coverage, particularly in post-emergence applications. In some cases — especially with ultra-coarse sprays — that’s true, Dahl says. Coverage can suffer, and penetration into the crop canopy can be weak. The right DRA, though, has been shown to increase droplets’ speed as they leave the nozzle, which improves penetration into the crop canopy.
“If we look where we have added in a DRA, it has actually increased the amount of speed of those droplets, so they’re going to go farther before they run out of energy, and we’re going to get better penetration of the canopy, better deposition farther down,” Dahl says.
Side-by-side comparisons in corn and soybeans using fluorescent dye tell the story more completely (see below). Without a DRA, Dahl’s slides illustrate that coverage is good on the top leaves of the crop but falls off quickly as the product moves down into the plant. With a deposition-type DRA, coverage is more balanced from the top to below the ear leaf in corn and throughout the soybean canopy.
The ROI Of Improved Product Applications
Better coverage does show up in yield results, Dahl reports. Across hundreds of corn fungicide trials, for instance, he says adding a DRA to the tank delivered an average yield increase of about 5.7 bushels per acre compared to fungicide use alone.
In wheat, similar work showed nearly a 4‑bu.-per-acre advantage.
There’s also an economic advantage in terms of product retention. When you reduce the number of driftable fines, more of the active ingredient you paid for actually lands and stays in your field instead of drifting away.
Dahl says not all DRAs and nozzle combinations are created equal. Some thicker, polymer-type products can narrow the spray angle or even increase driftable fines with the wrong nozzle used, especially Venturi designs. That’s why choosing proven products matters. He says oil-emulsion DRAs, in particular, have shown they can cut driftable fines without creating an overly thick spray or sacrificing pattern quality.
“There’s almost 500 labels that recommend using CPDA-certified adjuvants, and there’s over 200 products that are CPDA-certified adjuvants,” Dahl says, referencing the website CPDA.com. “We think that’s where you should go for information, and we thank you for that,” he adds.
