Droplet Size Determines Product Efficacy
Crop protection chemical manufacturers and application equipment manufacturers are both looking for a simple system to establish parameters for what equipment to use with what chemicals for optimum pest control and least drift potential.
Success in determining how to better apply products will result in reduced financial/legal exposure for chemical trespass by custom applicators, ag retailers, chemical manufacturers and farmers. Additionally, government regulators will be pleased with less potential negative environmental impact from off-target chemicals.
Work focusing on determining least drift potential is being done by researchers at a couple universities and collaboration by representatives of basic ag chemical manufacturers, adjuvant and surfactant manufacturers, distributors, spray equipment manufacturers, U.S. Department of Agriculture and U.S. Environmental Protection Agency.
The EPA is expected to issue its “Verification of Pesticide Application Spray Drift Reduction Technology” in 2013. Representatives of the various stakeholders provided recommendations for the verification protocol as participants of the Spray Drift Working Group.
Research to establish data relevant to reducing risk is not on hold waiting on the EPA. The most sophisticated research is being done at North Platte, Neb., where two wind tunnels were put in place by the University of Nebraska with financial support from private corporations. A high-speed wind tunnel can evaluate aerial application technology in winds up to 210 miles per hour, and the low-speed wind tunnel can evaluate ground rig application products in winds up to 15 miles per hour.
“We’re really trying to understand what the (pesticide) droplet size looks like under various application conditions—different nozzle selection, different orifice sizes, varied applicator pressures—and how that translates into off-target movement. And then taking those same parameters, how does that translate into pesticide efficacy?,” explained Greg Kruger, University of Nebraska, assistant professor, cropping systems specialist, working at the West Central Research and Extension Center.
DROPLET SIZE FOR EFFICACY
Boiled down to the simplest terms, the majority of work being done by Kruger, a university team and private company representatives is aimed at determining what droplet size provides the best efficacy for pesticides currently on the market. Besides there being hundreds of registered pesticides, the research is complicated by how adjuvants change the droplet size and weed control efficacy. Pesticides in mixture, in the majority of cases, come through spray nozzles in different droplet sizes than water sprayed alone.