Droplet Size Determines Product Efficacy
Howatt’s research has focused more on the weed-control efficacy in the field after application with different droplet sizes, and he has not gotten into the engineering of new nozzles or other equipment. He has relied on the TeeJet nozzle manual for approximation of droplet sizes being applied by different nozzles.
He noted because of the original simplified view from the EPA that larger droplets are better, application technology companies have been focused on promoting nozzles producing coarse to extremely coarse droplets. But bigger droplets, it is now thought, might allow more herbicide to roll off the leaves, especially depending on the plant species. There is no confirmation of this supposition as yet.
WIND TUNNEL INFORMATION
Kruger is doing some of the same droplet size and weed control efficacy work as Howatt, but Kruger has the advantage of knowing precisely what droplet sizes are being applied based on wind tunnel testing of nozzles and specific herbicide mixes.
Representatives of all phases of the industry know that coarse droplets will in general limit drift, but if a pesticide is not going to perform when applied with the wrong droplet size, there is no justification for the farmer using the product.
Industry participation in testing of pesticides and equipment to be classified as drift reduction technology is originally going to be a voluntary EPA program for companies. It is anticipated by many who know how the EPA works that not participating will eventually result in consequences. If a company cannot reformulate a product that performs best applied with small droplets, to one appropriate for application with coarse droplets, then the dreaded buffer zone restrictions could be quite substantial.
The first emphasis by the EPA is on classifying nozzles by their drift potential so that they can be assigned a drift reduction technology rating of one to four stars. This rating of nozzles is the easiest aspect of the whole drift reduction issue to standardize.
Kruger is hopeful that the EPA protocols for reducing drift are based on research already begun. He hopes the final protocol recommendations from the EPA follow the working group-submitted information to a large degree, although, he gives the EPA credit by saying it has “good insight and has done a lot of research on drift.”
DROPLET SIZE CALCULATOR APP
Having applicators informed and educated is a major aspect of what Greg Kruger, University of Nebraska, wants to happen. The data his team is developing is relevant to the real world, and that is why the research group created an iPhone and Android phone app so that “any pesticide applicator can easily access some of the data we have generated,” Kruger said. “What we have done with this app is basically establish a droplet size calculator.
“An applicator can enter what nozzle type is being used, what the operating pressure is, what orifice size is being used and what spray solution is to be applied. The app will provide the droplet size.”
Currently, there are limited herbicides referenced in the app. As research is completed in 2013, new spray solutions data will be added. The goal is to add different adjuvant classes and different products. He wants the app to have a “robust database behind it” so that applicators know what droplet size is being sprayed and to perform their application appropriately with limited risk of off-target drift.
The app can be found by searching the iTunes or Google Play Store with the key words of ground spray.