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Technology helps detail geeks save fungicide, time

One can just about hear the grin over the phone as canola grower Neil Rathgeber, of Churchbridge, Saskatchewan, talks about his experience the past two summers with fungicide applications for his canola. Both years, he reduced costs and saved time. He also was able to relax, letting the sprayer follow an accurate prescription for the application rates.


November 30, 1999
By John Dietz

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One can just about hear the grin over the phone as canola grower Neil Rathgeber, of Churchbridge, Saskatchewan, talks about his experience the past two summers with fungicide applications for his canola. Both years, he reduced costs and saved time. He also was able to relax, letting the sprayer follow an accurate prescription for the application rates.

The Rathgeber family manages 5800 acres of cereals and oilseeds. About 2005, the family began a process of moving into variable rate controls for the air cart and then for the sprayer. Instead of guessing and estimating how much product to invest in the acres, they have moved to precision applications. “Next year most of the farm will be in a variable rate program. We do soil tests in every field, and we do exactly what the soil tests say,” explains Rathgeber. 

Their variable rate fungicide application uses aerial images to determine where to apply fungicides, based on crop canopy. Sclerotinia has been the biggest challenge for their canola; the heavier the crop and thicker the canopy, the more disease pressure.

Real-Shot, real saving
To help develop variable rate prescriptions, Rathgeber uses agronomy consulting from an independent consulting company, Sure Growth Technologies at Langenburg, Saskatchewan, run by Terry Aberhart. Aberhart also manages and operates a 10,000-acre grain farm with his father, and is an Agri-Coach associated with the Agri-Trend Group of Companies. Justin Cleaver, a “geo-coach” with Agri-Trend, is also part of the team. 

High resolution digital photography is the first step in developing a prescription zone map for variable rate fungicide treatments. This Real-Shot Imagery is an Agri-Trend service that became widely available in 2008. A Massachusetts company, GeoVantage, owns the technology and 80 purpose-built cameras for the aerial photography. GeoVantage contracts worldwide for agricultural, forestry and other services. Private local aircraft based at Lethbridge, Yorkton and Steinbach fly the fields on orders from Agri-Trend; the imagery is processed remotely and images are uploaded within a day or two for use by clients. 

The digital Real-Shot photos are geo-referenced with one-metre resolution. Each field is captured in natural colour, false-colour infrared (FCIR), normalized difference vegetative index (NDVI) and a raw digital image known as 4-Band GeoTiff or GeoJpeg.

When Aberhart gets the images from the flyover, he inspects the growing conditions in Rathgeber’s canola fields on foot to assess the risk of disease development and the payback on fungicide application. They talk it over, set up a zone-based treatment plan, and have it programmed for the controller by Cleaver. Many self-propelled sprayers are now set up for GPS-based variable rate applications, with sectional boom controls and variable rate controllers. “A guy doesn’t have to spend anything additional on his spraying equipment,” Aberhart says. “His sprayer is GPS ready. It has all the valves and equipment to run these functions. It’s become much easier for the farmer to use.”   

The high-resolution images taken by aircraft are also a breakthrough in technology. The advantages of high-resolution, aircraft-based options, Aberhart says, include the ability to fly below cloud cover, control of image capture dates, and in-season decision-making support.

The smallest bit of data on a typical Landsat photo represents a 30-metre square, or about 90 square feet. That is sufficient for looking at the general crop condition, but inadequate for precision guidance on a sprayer that can manage 17-foot boom sections. “Thirty-metre resolution doesn’t work very well where you have a lot of quick transitions, like drowned out areas or ditches, and we can’t always get the image in a timely fashion,” Aberhart says.

A midway option, with a five-metre resolution, now is offered by RapidEye, a company based in Germany. It can be used for zone maps, but has the same issues with cloud cover that a Landsat photo does. 

One further option for growers on the eastern Prairie is a variable rate fungicide program offered for the first time in 2010 by Prairie Agri Photo Ltd., of Carmen, Manitoba, in conjunction with Agri-Trend Geo Solutions Inc. It is very similar to Real-Shot, but uses a different camera technology with half-metre field resolution.

Making it work
High overhead, one windy morning in early July 2010, Rathgeber heard the buzz of a plane and recalled that he had asked his consultant for an aerial flyover. About five days later, he put a prescription card into the sprayer’s rate controller and headed for his canola fields. His cost for the flyover this time worked out to $3 an acre. It gave him four high-resolution images of each field. “We could pick out all the vegetative growth, see where we had to put on more fungicide and where it didn’t need applying. Without that, we’d have just sprayed piles of acres,” says Rathgeber.

After receiving the prescription from Aberhart, Rathgeber plugs the information into his rate controller, and heads to the field. “It just comes up nice and easy. It’s real easy to use. For a few years I was scared of it, but not now.”

He is using a 90-foot sprayer with five boom sections. It automatically steers and varies treatment rates for three application zones, shutting off boom sections to avoid overlap. “We’ve had no troubles with variable rate,” Rathgeber says. “My biggest problem is if I push the wrong button on the GPS. It’s pretty straightforward, pretty simple. Actually, I don’t even want to do a regular field anymore. You punch in the field, load the card on to the GPS, and away you go.”

Instead of getting 60 acres to a fill of Proline or Astound, Rathgeber covers 75 to 100 acres with a tank. He recalls a 300-acre field of canola that only needed spray on 197 acres. “That saved a tank-and-a-half of filling and spray time, too. It adds up pretty quickly,” he says. “You can see exactly where you have water sitting and where you need to improve some drainage. It’s not just a one-shot deal. There’s a lot of information there.”

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