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Corn+Soybean Digest

Postemergence Spraying Tips From A Pro

John Obery custom sprays over 30,000 crop acres per year. That's on top of spraying 2,800 no-till acres of his own.

Bottom line lessons learned: He's found that two tools - drift-control nozzles and a new spray adjuvant - can virtually eliminate pesticide drift problems. They also crank up herbicides' weed-killing performance.

Drift cuts two ways, the Metamora, IL, no-tiller reminds.

One, it can damage or kill crops that were not targets on your farm, or get you in a heap of trouble with a neighbor. Two, it can reduce the potency of your weed killers because some spray misses the target.

Both situations can cause you embarrassment, money or both.

"We all know, of course, to avoid spraying under gusty wind conditions and to spray with the wind blowing away from sensitive crops and our neighbors," declares Obery. "It is serious business.

"When we drift on a neighbor, it is a concern," he adds. "But when a neighbor drifts on us, it is a crisis situation."

Because the spray window is relatively short and he has thousands of acres to cover, the two tools to reduce drift and improve chemical performance have made a big impact on his business.

Though not an ag engineer, Obery has worked with Bob Wolf, University of Illinois ag engineer, among others. And he has been a student of drift research, especially that of Roger Downer, an ag engineer at the Ohio State University Laboratory for Pest Control Application Technology.

Here are details on the tools:

Drift-control nozzles. These are available from several spray-equipment companies. Obery uses Turbo TeeJets.

"These nozzles are the first step in reducing drift potential," he declares. "They're an absolute must in improving spray application for both pesticide performance and drift reduction."

The goal for optimum droplet size is 200-600 microns, Obery explains. A spray droplet falling 3 foot with a 5 mph wind will drift less than 10 foot if it is 200 microns or larger. If it is less than 200 microns, it'll drift more than 10 foot - and that's not acceptable, he contends.

There still are farmers who do what he used to do: use flat-fan nozzles at 60 psi, Obery says. When he found out the score, he quit.

At 60 psi, 24% of the spray volume is driftable fines of less than 200 microns. "That's simply unacceptable," Obery challenges. "We can't do that anymore."

A Turbo TeeJet 110 degrees 05, using from 20 to 90 psi, still has a median micron size of 400 or more, which gives an operator a lot of flexibility, Obery explains.

DR2000 adjuvant. DR2000, a new biodegradable, short-chain polymer, is the active ingredient in the commercial product Array, which also contains ammonium sulfate. With normal spray volumes, use 9 lbs of Array for 100 gallons. (Very recently, DR2000 has been included in several other adjuvant formulations.)

"Array minimizes or eliminates spray drift," Obery asserts. "It improves spray droplet retention by 30%. It does this with less spray droplet bounce and runoff. And ammonium sulfate ions improve pesticide performance."

With the adjuvant, drift can be reduced 77%, according to Downer's research. Together with the Turbo TeeJet nozzles, it can squeeze driftable fines down to 1%, notes Obery.

"I have used Array in all of my at-planting burndowns and all my post applications of herbicides the last two years. It has really given me peace of mind. And in the last two years, I have not had any field resprays or drift complaints."

Looking at herbicide performance, Downer found in his research that DR2000 markedly increased the efficacy of Roundup Ultra.

"What he found was that Roundup Ultra plus DR2000 gave a 300% increase in performance vs. Roundup Ultra alone," Obery chortles.

Commenting on these two tools for cutting spray drift and hiking herbicide performance, Obery says that here is the bottom line for him in his operation:

"Clean fields and satisfied customers mean repeat business for me, and these tools can help you in your crop farming operation as well."

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