While regulations, or lack thereof, governing the use of crop protection chemicals applied by unmanned aerial vehicles (UAVs) vary widely across the globe, U.S. growers and applicators are currently operating under a grace period of oversight. That isn’t likely to last long. 

Neill Newton, Syngenta’s Global Drone Applications Manager, says major chemical companies are funding studies to better standardize the labeling of products that can be applied to crops by drones in hopes of reducing future red tape in product labeling for UAV use.

“The EPA has essentially told us that currently, as long as a product has an aerial label, it can be applied from a drone as long as various state regulations apply,” Newton says. “That assumes the operator has the proper licensing and certifications.

“EPA also told us that’s not going to be the case forever. They will want to assess the risks from these applications in the future, just as they assess risks from ground rigs or piloted aircraft.” 

To address future regulations from EPA, and similar organizations around the world, Newton says 9 major crop protection chemical companies pooled money initially in 2021 to fund research and generate data under the Unmanned Aerial Pesticide Applications System Task Force (UAPASTF). The thrust of the project is to study drift data, human operator exposure data, and other research that agencies such as EPA, Canada’s Pest Management Regulatory Agency (PMRA) and regulators in Europe and Australia will be requesting.

Current membership in the organization includes BASF Corp., Bayer CropScience LP, Corteva Agriscience, FMC Corp., Gowan Co., NuFarm Americas, Syngenta Crop Protection and Valent U.S.A.

As part of the effort, UAPASTF also developed a ‘best management practices’ (BMP) document concerning UAV-based application of pesticides and sought input from global stakeholders including UAV application and manufacturing companies, academic and government experts, and regulatory agencies.

“In the future, when a company approaches EPA to ask what’s needed to get a registration for its new product, EPA will say, ‘We need some data,’” Newton explains. “We don’t want to generate data for every new product developed, so our goal with the task force is to generate reference data from which we can build a mechanistic model — similar to AgDRIFT Plus — to simplify the process.”

AgDRIFT Plus is the current version of the AGricultural DISPersal (AGDISP^®) model developed by the U.S. Forest Service, created by the EPA, the U.S. Department of Agriculture's Forest Service, and the Spray Drift Task Force. It has the capability to assess a variety of spray drift conditions from agricultural applications and off-site deposition of liquid formulation of pesticides. The model can be used in estimating downwind deposition of spray drift from aerial, ground boom and orchard/vineyard airblast applications. 

He says AgDRIFT Plus can answer some of the questions regulators will have about drift, but currently there is very little regulatory quality data — in other words, sufficient replications from wide ranging research locations — to cover all concerns the agency may have in the future. That’s what UAPASTF is doing with studies conducted in 2023-24 in the U.S., Spain, Hungary and Australia, which are currently under review and in the reporting process.

The task force enlisted the collaboration and approval of the global regulators likely to be assessing new products in the future, explaining to them the data being generated will be of little help if the regulators aren’t willing to accept it as good lab practice (GLP) protocols backed by regulatory quality research.

“We used Stone Environmental (with offices in the U.S. and Canada) to conduct the trials in all of our sites — regardless if they were in Australia, Brazil, College Station, Tex., or in Europe. In all cases it was Stone Environmental’s pilots and equipment running the experiments and collecting the data,” Newton explains. “We tried to eliminate as many variables as possible in the 10 global trials.”

The UAPASTF will use the reports for further guidance from EPA and PMRA.

“Our goal was to have the testing be sufficient on both sides of the Atlantic and wherever it’s used,” Newton says. “As you can imagine, we’re getting the pretty much the same results across the trials. We’re using the same drone under the same conditions, and in each case we had representatives of the local regulatory agencies involved in conducting the trials to help establish their confidence to accept the data in their ultimate risk assessments.”

Ideally, Newton says, the data would underlie a mechanistic model that would include UAV use as a dropdown category in applications such as Ag Drift Plus, which currently assesses risks for given products according to application equipment.

“In this case, the dropdown would include a selection for a multi-rotor drone and you wouldn’t have to do the testing for every single product you’re trying to register, because our models would have given us replicated research-quality outputs to give to EPA for their consideration in label guidance,” Newton explains.

Likely Caveat

As the task force presents its findings to global regulators, Newton says there may be a need to do further research based on some modern drone technology not used in recent studies. 

“The drone we used across the project was a DJI T-30, equipped with standard hydraulic nozzles,” Newton says. “While traditionally popular, the T-30 is much different than the most common drones in aerial application use today — most of which are equipped with rotary atomizers.”

While the data generated in UAPASTF studies were based on fine, medium and coarse droplet sizes, the question arises, says Newton: “If you spray fine, medium and coarse droplet sizes from a rotary atomizer, will you get the same results?”

Researchers may need to revisit those concerns to generate data to evaluate the difference in nozzles.

“So that’s the next step,” he says. “We’ll have these meetings with all the regulatory agencies across the world in hopes of establishing what the next steps look like. I think the task force has made a lot of great progress, but there’ll be a lot of work that remains to really wrap this up and put a bow on it.”