Spraying your fungicide in “the zone”

With Bayer’s new “Zone Spray,” farmers can skip the fungicide in some parts of the field

If Warren Bills has his way, farmers will have a better way to forecast sclerotinia than the old wet boots and weather test.

“We believe there is a better way to manage the risk of that disease and the returns growers get when they spray,” Bills told agronomists and industry at Bayer’s Ag Summit in November. Bills is the business development manager of digital farming for Bayer Crop Science.

Bayer has dubbed that process Zone Spray. The idea is relatively simple: identify variable canola fields and spray high-producing areas that are more likely to develop disease.

“We also know in those same fields there are areas that have lower potential and if we were to apply in those areas, we may not see a positive return,” says Bills. He adds fungicide rates won’t vary — it’s just an on/off application.

How it’s done

Zone Spray is still in the early stages, as Bayer evaluates how the technology works in the field and tests the agronomy behind the idea. It was first tested in 2015 and in 2016 expanded to include over 35 growers.

The first step is to set up a field boundary, Bills says, and only evaluate information within that boundary. Their technology partner, Planet, then snapped satellite photos of the canola fields in mid to late June. The fields were at peak biomass, before flowering.

Biomass is one of the risk factors for sclerotinia, Bills points out. By analyzing the photos, they were able to break the fields into seven management zones, based on biomass.

Farmers will then looked at the photos and decide where they wanted to apply fungicide. Bayer created a widget that showed the fields and the management zones. Any areas the farmer decides not to spray will disappear from the map.

But there is a “technology gap,” Bills says. For example, if a farmer gets into the field and decides he’s not comfortable with the spray decision he made in the office, he should be able to change the prescription in the tractor cab. But that wasn’t an option this last year.

Zone Spray also runs with the assumption that weeds are controlled. Weedy areas could show up as crop, Bills says. First-time users often want to groundtruth the field maps first, he adds.

“But did we have growers that didn’t go in the field and run those toggles? Absolutely. Mainly because we made it instantly visible when they turned it off and on in that map screen. They knew their fields really well.”

Early results

Once the spray window passed in late July, fields were scouted and infection was measured in both the untreated checks and the treatments in each zone.

Results are preliminary but the untreated checks in the high biomass zones had higher sclerotinia rates than the lower biomass areas. Bills says there also seems to be a trend of higher biomass zones showing a greater yield response to fungicide (Proline) than low biomass zones. In some fields, low biomass zones had no response to fungicide applications.

Given the high amount of moisture in 2016, the transition between on/off spray zones was quite definite, Bills says. The threshold for spraying might move in years without those extremes. Bills says they need to test the system in more fields and look for trends across years.

Weather conditions in 2016 favoured sclerotinia. In a dry year, Zone Spray might allow farmers to protect high biomass areas instead of not spraying at all, Bills says. It will “smooth out the decision-making for growers,” he says.

“Growers that are fully applying today, yes they may apply a little bit less,” he says. But Bills hopes to bring in variable fields that aren’t being sprayed at all by improving the economic return for farmers.

“We expect, when we apply at $20 per acre product, that we’re going to get back $40 per acre,” says Bills. If there are areas that provide a negative ROI, “all that does is whittle down ROI.”

Bayer doesn’t intend to provide prescriptive, hands-on services with Zone Spray. Instead, the company intends to partner with agronomists, says Bills.

“When you buy product from Bayer that’s been augmented by digital tools, we want it to be researched by Bayer. We want it to perform properly.”

About the author

Field Editor

Lisa Guenther is field editor for Grainews based at Livelong, Sask. You can follow her on Twitter @LtoG.

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