Ultra violet lamp robots tackle grape powdery mildew

But instead of being armed with a spraying system to apply fungicide, they will be equipped with ultra violet (UV) lamps that studies in the United States have shown can suppress the fungal infection – and also downy mildew – on a range of crops.

Effective suppression of powdery mildew

“For Chardonnay grapes, we’ve got effective suppression of powdery mildew over a period of two years, with treatments once a week,” said Cornell AgriTech project leader David Gadoury, senior research associate in the Department of Plant Pathology and Plant-Microbe Biology.

Lance Cadle-Davidson, a research plant pathologist at the United States Department of Agriculture, notes that a typical grape grower will spray fungicides for powdery mildew management between 10 and 15 times each year.

Damaging effect of UV light

“Everywhere grapes are grown, growers have to worry about powdery mildews,” he said. “They have co-evolved with the plants they attack over millions of years and often develop resistance to chemical treatments very quickly. But their evolution has also given them an Achilles heel: adaptation to natural cycles of light and dark. We can exploit the damaging effect of UV light on their DNA by applying it at night when the pathogens do not receive the blue light necessary for their repair mechanism to work.”

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Commercial robotic units

The Cornell AgriTech researchers have teamed up with Norway’s Saga Robotics, the company behind the Thorvald autonomous vehicle, to develop commercial robotic units that can work their way through vineyards to apply low level UV light with minimal labour requirement.

Two such robots have been involved in trials on Chardonnay grapes this spring at Cornell’s Geneva research vineyards and at Anthony Road Wine Company, both in New York State.

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Detect and quantify mildew on grapes for a targeted approach

At present, the robots apply the same dose of UV light to all vines but Lance Cadle-Davidson is developing imaging technology in partnership with scientists at Carnegie Mellon University to detect and quantify mildew on grapes for a targeted approach to UV light treatment.

Saga Robotics is familiar with UV light treatment on other crops, notably strawberries, where the company says weekly exposure to shortwave UV is “highly effective” in suppressing powdery mildew.

Repeated trials in US commercial crops and high tunnel systems in Norway are said to have produced results as good as the best fungicides.

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Lance Cadle-Davidson concurs: “Field trials in co-operation with the University of Florida successfully controlled powdery mildew in strawberries over the past four years,” he said.

Saga’s technology is also applied to cucumber and tomatoes in greenhouses and USDA collaborations with universities other than Cornell have led to trials with squash, pumpkins, cucumbers, hops, basil and industrial hemp.