Drift Reducing Agent (DRAs) are added to tank mixes to reduce pesticide drift into undesired areas, ensuring that the pesticide reaches its intended target and does not float in the air for an extended time. Drift control has always been important in spray applications. The importance of DRAs has increased since new dicamba herbicides came into the market. As the adjuvant industry works towards having DRAs approved as a mitigation strategy in the pending EPA herbicide strategy to remediate impacts to farmers.
Since 1972, Pesticides have been regulated under what is known as the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). This act was intended to be the sole federal statute for regulating pesticides, but the passage of the ESA in 1973 added complexity by requiring federal agencies to consult with the National Marine Fisheries Service (NMFS) or the Fish and Wildlife Service (FWS). Decades of lawsuits and legal issues have come to a head and the industry is now looking at major changes to herbicide labels and application restrictions. The result has been a newly drafted Environmental Protection Agency (EPA) Herbicide Strategy that targets the reduction of herbicide impact on endangered and threatened species.
The history and impacts of this issue are summarized well in this article by Scott Rawlins, Director of Governmental Affairs with the Council of Producers and Distributors of Agrotechnology (CPDA).
In short, the impact of the proposed Herbicide Strategy could create larger hurdles such as time and data requirements for pesticide registration and the requirement of buffer zones for farmers. The requirement of buffer zones for certain herbicides could significantly reduce the number of acres in production across the United States and reduce the number of weed control options available to farmers. Fewer herbicide options could result in lower productivity and further exacerbate the development of resistance in weed populations, ultimately leading to more herbicide use.
As the EPA implements this regulation, it’s critical to understand the role DRAs play in minimizing direct implications for farmers. The increased buffer zone requirement sounds intimidating, but including a DRA can reduce the requirement by up to 30%. Applying strategies to stay compliant and keep acres in crop is essential to maintaining bottom line and minimizing risk.
By reducing drift, they increase the deposition. Drift Reducing Agents minimize drift by increasing droplet size and reducing driftable fines by modifying the spray solution’s viscosity. Droplets that are smaller than 150 microns are considered driftable fines. The optimum particle size to prevent drift ranges between 250 -500 microns.
When using DRAs, it is essential to consider the labeled rate, the proper nozzle type and size, and the correct sprayer pressure. If drift control agents are used at a higher than recommended rate, the DRA can clog the spray nozzle or create too large droplets, leading to insufficient coverage. An inefficient spray pattern can also be caused by using the wrong nozzle size or spray pressure. Following nozzle manufacturers’ guidelines is necessary to ensure an effective spray pattern.
When spray solutions pass through small nozzle openings under high pressure, they form a range of droplet sizes, including very small droplets that are prone to drift. These tiny drops of liquid are easily picked up by air movement and do not reach the target application area. When these droplets land outside of their intended target, they can cause damage that can be costly or take a long time to restore. Droplets that drift do not have proper deposition and do not ultimately accomplish the goal of the application, which is to deliver the active ingredient to the target.
There are two main classes of drift reducing adjuvants: 1) oil emulsion DRAs, and 2) solution DRAs. Emulsion DRAs are oil-based products that create an emulsion when added to a spray tank. These products modify the shape of the spray sheath coming out of the nozzle, reduce the number of small droplets, and improve spray droplet size uniformity. Emulsion DRAs are typically low viscosity (i.e., easy to handle). These products work with all nozzles but are not optimized for air-induction nozzles.
Solution DRAs include those that utilize polymers like polyacrylamide and guar to increase the viscosity of the spray solution. These products reduce the fraction of driftable fine particles and typically create larger droplets compared to emulsion DRAs. Solution DRAs are highly-effective and work across all nozzle types, including air-induction nozzles. Solution DRAs can be higher in viscosity and more difficult to handle and mix compared to emulsion DRAs.
Although regulations around pesticide use continue to evolve, at Exacto, we focus on fine-tuning and developing adjuvants that mitigate environmental impacts. The video below shows the spray pattern with water (left) and water with an Exacto DRA at 0.4 oz per gallon (right). Both are sprayed with an XR110015 spray nozzle at 40 PSI at 11 gallons per acre spray volume. The video shows that adding a DRA leads to more consistent spray quality due to more right-sized droplets. The deposition result between water and DRA + Water is visible on the yellow spray card, where the dark dots show where each droplet landed. The difference seen in the actual spray in the video corresponds with the better deposition of the DRA + Water droplets on the spray card.
In a constantly changing industry with more and more complex tank mixes, it’s imperative to stay on top of regulatory requirements and how innovative technologies can maximize input efficiency. DRAs are a valuable tool for all applications, improving the amount of sprayed material that reaches the target, and contributing to more sustainable cropping systems.
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