Zeros in on target | Charged droplets attracted to underside of leaves
An aerial desiccation mix applied at only one U.S. gallon of liquid per acre achieved 100 percent kill in an Iowa soybean field last summer.
The potent mix had a one to three ratio of Roundup to water, applied at a rate of one gallon per acre through a Spectrum electrostatic system mounted on a Robinson R44 helicopter.
“It just simply annihilated every living plant in the field,” said Gary Johnson of Johnson Helicopter Services, who made the application.
“We’ve always been told we do a better job with more water, but that’s just not true. It’s the exact opposite. Less water gives us a better job. The product is more concentrated, but you have to get it all on the plant, not the ground. That’s where the electrostatic comes in to play.”
A significant amount of spray normally falls on the ground or drips off the leaves and ends up on the ground. However, charged droplets are attracted to the leaves.
The Earth carries a negative charge, but the plants are taller than the field surface, which is where the charged droplets go. Rather than dripping off the leaves, droplets bond to the plant.
Johnson said the economics of electrostatic spraying extend beyond the obvious benefit of 100 percent kill on the field.
Helicopter applicators typically put down two to five U.S. gallons of liquid per acre.
Even if an applicator has already cut down to two gallons, another 50 percent cut means the pilot can spray twice as many acres per fill. The economic benefit can be huge for an applicator still spraying five U.S. gallons of liquid per acre.
Each fill can take five minutes or longer, depending on the proximity of the field to the service truck. Cutting the number of fills per day keeps expensive helicopters in the air and working more hours.
That’s especially critical in fixed wing and helicopter applications because of the relatively small payload compared to ground sprayers. Both the applicator and the customer benefit from the efficiency.
“There’s one company I spray for that says they’ll only order my electrostatic helicopter now. They won’t use anything else.”
Another important feature of the electrostatic system is the distribution of active product on each leaf.
“It’s a big advantage to have the spray go underneath the leaves. That’s especially good for insecticides and some fungicides,” said Johnson.
“I don’t know of any other system anywhere that can do that. The spray pattern literally wraps itself all around the plant. And that’s why we can cut back on product and water,” he said.
“Of course, I can’t recommend anything that’s off label, but guys are cutting their chemical rates by 20 percent and getting the same or better coverage than the full 100 percent rate.”
Johnson has one Bell Long Ranger and three Robinson helicopters. He has electrostatic on only one of the Robinsons, but plans to equip the other three helicopters with the $38,000 Spectrum systems next year.
He does not charge extra for the Spectrum-equipped applicator, nor will he charge extra after the entire fleet is equipped.
“Here’s why. This electrostatic system is leading edge 21st century stuff. Regular nozzles? They date back to the 1950s and 1940s. That’s obsolete,” he said.
“Farmers have come to expect that the people who do custom work for them will use only the latest technology. They deserve the latest and best technology. South America is way ahead of us. They’ve been using electrostatic sprayers for years.”
Johnson said the concept of using charged droplets for better coverage with reduced water should theoretically work for ground applicators, but the SprayCoupe foray into that technology was thwarted by dust kicked up by the machine.
For more information, contact Gary Johnson at 712-310-6844 or visit www.spectrumsprayer.com.