Northwest wine industry looks at UV light to treat powdery mildew | Orchards, nuts and vines
TURNER, Ore. – The robot glows an eerie green in the darkness of the night as it maneuvers over rows of vines in Willamette Valley vineyards.
Developed by Norwegian company Saga Robotics, Thorvald – as the system is named – is an autonomous, self-driving vehicle that looks a bit like a small shed on wheels. Inside, it is equipped with a special strip of ultraviolet lights designed to suppress powdery mildew and other plant diseases.
As research continues to demonstrate the effectiveness of UV light as a management tool for farmers, Willamette Valley Vineyards has become the first commercial company to adopt Thorvald in place of traditional chemical fungicides to control powdery mildew. in grapes.
“We see this as a remarkable opportunity for our industry to grow high quality grapes and to do so in a very natural and sustainable way,” said Jim Bernau, founder and CEO of the winery.
As the Bernau and Willamette Valley vineyards began experimenting with UV light last year, scientists around the world have conducted field trials for decades, covering a variety of crops including strawberries, apples, cucumbers and hops.
Today, a research team led by David Gadoury, a plant pathologist at Cornell University, is gathering data and refining treatments using UV light, with promising results.
Gadoury was the guest speaker at a webinar hosted on May 27 by Washington State University and the Washington State Wine Commission, providing winemakers with the latest information on UV light and its potential as alternative to fight against plant diseases.
Powdery mildew, in particular, is one of the most prevalent problems in the wine industry. If left unchecked, the disease can reduce crop yields by up to 95% and degrade wine quality.
The first field trials using UV light took place in 1991, although they were not successful, Gadoury said. While it effectively reduces powdery mildew in grapes, it also defoliated vines and wilted fruits, resembling miniature red potatoes.
Then came a key discovery 10 years ago. A doctoral student in Norway found that UV light was much more effective in killing powdery mildew at night, when pathogens’ natural systems to repair their DNA shut down to save energy.
Not only are pathogens more sensitive at night, but Gadoury said they were able to use 10% less UV-C to achieve the same levels of disease reduction, to levels that will not cause harm. plants or fruits.
“Pathogens like powdery mildew and many other organisms really don’t like UV light at night,” Gadoury said. “This means we can kill them with a fraction of the required dose during the day.”
New trials began in 2017 at a commercial strawberry farm in Florida. This time, they were a resounding success, with significantly better performance than chemical fungicide applications.
Additional trials are currently underway in places like California and Nova Scotia, in Canada, as well as overseas in Europe.
“I think we are beyond the point where we need to worry about whether or not this technology will provide lasting control of strawberry powdery mildew,” Gadoury said. “It works pretty well.”
The technology is also put to the test in the vineyards of the Northwest.
Michelle Moyer, statewide wine extension specialist for WSU, leads a national program on fungicide resistance. Last year, she started experimenting with UV light, studying the differences in when and how often.
Although the past year has seen low disease pressure overall, Moyer said using UV light at seven-day intervals has shown “fairly acceptable” levels of disease control.
“We saw this and we liked this kind of data,” Moyer said.
Gadoury said UV light also shows promise in treating other diseases like sour rot and killing the eggs of different species of mites.
With the success on several crops and pathogens, UV light has also started to gain the attention of equipment manufacturers like Saga Robotics, Gadoury said. Saga Robotics introduced the Thorvald system last year and partnered with Willamette Valley Vineyards to deploy its first business unit.
The winery’s interest in UV light actually started as a way to kill the coronavirus at the height of the pandemic last year in its tasting room, south of Salem.
“We’ve learned that it can be used to kill viruses and other things like powdery mildew – naturally, without the use of chemicals,” Bernau said.
In addition to WSU, Gadoury worked with researchers at the USDA Agricultural Research Service Station in Corvallis, Ore., On field trials.
Gadoury warned that UV light is not a quick fix that will eliminate all pesticide use, but at least in the fight against powdery mildew, it appears to match or exceed some of the best fungicide applications on the market.
“While these machines have a certain ‘cool factor’ – they’re fun to watch – it’s the research into epidemiology, pathogen ecology and photobiology that really makes them work,” he said. . “Otherwise, it’s just a toy.”