Late-season ground applications

Late-season ground pesticide application is increasing and for good reasons. Grower-proven yield benefits from late-season fungicide applications in high-yielding corn and concern over more diseases in soybeans and other crops have spurred demand.

At the same time, aerial applicators, once the dominant, if not the only alternative for a late-season strike against disease and other pests, face new obstacles. They are being driven from the sky by an advancing army of wind towers, power transmission lines and organically farmed fields (no matter how limited the risk of drift).

The combination is sparking increased interest in high-clearance application rigs among  applicators, and the companies that make equipment are responding.

"Our customers are reporting significant yield responses with late-season fungicide applications, shooting for 10 to 15 bushels per acre with reports of as much as 30 bushels per acre in extreme responses," said Jim Williams, Hagie Manufacturing.

Corn isn't the only crop where late-season application interest is growing, suggested Dave Webster, AGCO Application Equipment. "Wheat, soybeans and cotton are all seeing late-season application yield response," he said. "Yields are higher, so there is more yield to protect."

Although AGCO hasn't entered the ultra high-clearance market, its RoGator systems have been redesigned for less crop impact in season. "In addition to larger booms, we've definitely cleaned them up in terms of wheel packages that are narrower and smoother for crops to flow around. The underneath is a lot cleaner, leaving less for taller crops to catch on and be damaged," said Webster.

Commodity prices play a role as well, added Webster. "When commodity prices spike, the economic threshold for application is lowered," he said.

Nick Weinrich, John Deere, agreed that commodity prices play a big role. As product line manager for the company's self-propelled sprayers, Weinrich measures interest in late-season applications by growth in interest in the company's high-clearance kits available for the 4730 and 4830. The kits add 16 inches of height, bringing the sprayers to 76-inch ground clearance, enough to lift them above eight to 10-foot corn.

"While the yield boost is the driving force, interest was down last year, but this year we are seeing growing demand again," he said. "It is a changing market, depending on the commodity prices."


Increasing Benefits of Ground Application

Hagie has been building high-clearance sprayers for more than 60 years. In fact, the company's first sprayer was a modified detasseler. Although in-crop and late-season application is nothing new for the company, Williams said there is a growing recognition that the benefits of ground application, especially fungicide ground application, are outweighing those of aerial.

"Aerial applicators cover ground faster," admitted Williams. "However, ground applicators do a more consistent application without the streaking that can occur with aerial application. Ground has guaranteed coverage tip to tip."

It is volume options that really tip the pendulum with fungicide applications, he added. "We can run significantly higher volumes than aerial," he said. "Instead of two to three gallons per acre, we do 10 to 15, even 20 gallons. We get product clear down into the canopy, down into the roots."

Several equipment advances in recent years, beyond simple ground clearance, are also having an impact on ground application equipment suitability. One is the size of application equipment tanks. Ground rigs can simply cover more acres today with less time lost on refills. Another big change is spray booms, as Hagie and others have introduced 120-foot spray booms.

"Wider booms mean fewer passes through the field," said Williams. "We also have introduced (Sept. 1) a rear boom the width of the machine specifically for fungicide applications."

Hagie's front-mounted spray boom has always offered excellent visibility of nozzles and patterns, not to mention how close a boom tip is to a tree or fence post. However, fungicide applications in front of the cab raise concerns over operator safety, and fungicides tend to leave a sticky residue on equipment. The new boom fits Hagie 2005 and newer STS sprayers.


Added Accuracy With Precision Ag

Another recent advance vital to late-season success is precision guidance. In those cases where RTK sub-inch repeatable accuracy is possible, wheels can be guided carefully between rows using maps. Williams said Hagie offers that same kind of accuracy in-season without RTK, planting maps or a GPS receiver.

"We use Reichardt Ultra Guidance PSR tactile sensors," he explains. "The machine guides itself down the field, keeping wheels between the rows, no matter who planted it or how. We don't have to worry about the accuracy of a field map."

One thing guidance systems, whether GPS or tactile based, can't change is end rows. Here, too, engineering advances are playing a role, making late-season applications less damaging. All-Wheel Steer from Hagie and four-wheel steering offered by AGCO cut the turning radius by as much as half. In-line tracking also means only one set of tracks is left behind. As a result, fewer stalks are run down and fewer ears lost.

Even tires are playing a role in improved efficiency and reduced crop impact. AGCO and Michelin recently introduced the SprayBib tires for use on RoGators. The tires handle heavier loads and run on lower pressure for less compaction, better traction and less slippage. They can run at 40 mph highway speeds between fields. They also feature a flexing sidewall.

"As it flexes, it tends to push plants out of the way, rather than running them down," said Webster.

Williams applauded the new tire design and looks forward to competitive introductions, as well as access to the Michelin technology. "We are always working on getting our drive systems as narrow as possible," he said. "The problem is that tire manufacturers haven't put a lot of effort into designing tires for high-clearance type sprayers. Now they are coming to the plate with new offerings. They do a good job getting the tires narrow, but the load rating is the limiting factor."

As equipment becomes available, it gives ground applicators more reason to compete with aerial applicators for the late-season spray market, added Weinrich. "A lot of customers tell me that if they are going to pay an aerial applicator to apply fungicides, why not spend that money on their own rigs," he said. "They're able to utilize equipment over more ground and make more money with it."


Crowded Skies

The combination of improved efficacy, higher volume and better equipment might be enough in themselves to drive more acres to ground application and more application fee income to retailers and custom applicators alike. However, they have a powerful and growing ally in wind towers and other obstructions.

Drive across Iowa, Minnesota, Illinois and the Dakotas. Wind towers are becoming as common as silos and grain bins. However, not many grain bins sit in the middle of fields, nor do they prevent application around them. Add transmission lines, cell phone towers and unmarked meteorological data towers, and the skies above much of the Midwest are becoming crowded and dangerous for aerial applicators.

"In many areas, ground rigs are becoming more popular simply because of the number of wind towers and other obstructions," said Williams. "The FAA doesn't want pilots too close to those towers, and the pilots don't want to be there either."

Not only do applicators have to worry about the towers and blades, but also air turbulence can carry half a mile down wind. Some aerial applicators are adding an application surcharge when in the area of a tower, while others simply refuse to work around them. Adding to the problem is that towers tend to be placed in the middle of fields and not often by themselves.

"When you get 205 windmills spread out as we have in one wind farm just south of our plant in north central Iowa, they cover a fair number of fields," said Williams. "There are three more wind farms within a 100-mile radius. As the pilots cease going in, the co-ops and other retailers are picking up acres and income."

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