Newswise — ITHACA, N.Y. – Thanks to the work of an international, multidisciplinary team of researchers led by Cornell AgriTech’s David Gadoury, farmers may no longer have to rely exclusively on fungicides to suppress destructive plant pathogens like powdery mildew.

Over the last five years, researchers have refined the science and applied technology behind using ultraviolet (UV) light to kill the fungi that causes powdery mildew (PM), opening the door for the technology’s use to control other plant pathogens.

“In more than three years of trials, UV light applications worked as well as or better than available fungicides, killing 95 percent of PM in field strawberries. We’ve seen similar results in field and greenhouse trials of basil, roses, grapes, strawberries, rosemary and cucumbers,” said Gadoury, senior research associate in the Section of Plant Pathology and Plant Microbe-Biology.

Recent research from Gadoury’s lab – in collaboration with the U.S. Department of Agriculture’s Vitis Gen2 grape research project – indicates that UV light may also control downy mildew, one of the most destructive plant pathogens for a variety of plants.

In research trials over the past few months, pretreatment of grapevines with UV light activated their natural resistance to infection, something that the downy mildew pathogen can usually evade. The research suggests that UV light pretreatments may boost overall plant defenses against pathogens.

Controlling crop diseases is a complicated process of managing resistance to available treatments while fighting multiple pests on multiple fronts. Gadoury said that if farmers can knock out pathogens that are difficult to suppress with fungicides, they can more efficiently manage the remaining diseases and insect pests. Using UV light to do this allows growers to use fewer fungicides, preserve their effectiveness and see significant savings.

This option is especially critical for organic growers, who often have a more limited arsenal of control measures. For high-value specialty crops like strawberries, grapes and greenhouse cucumbers – some of the most heavily treated with fungicides – using UV light could expand organic production. 

This year, farmers will have more chances to see the effects of UV light on crops. Working with leading growers and extension divisions across the U.S., the team will conduct nearly 20 trials with strawberries, squash, pumpkins, cucumbers, grapes, hops, basil and industrial hemp. In New York, the first commercial grapevine field trial will run in Hammondsport, New York, at Bully Hill Vineyards.

The team’s work is supported by a $1.7 million Organic Agriculture Research and Extension Initiative grant from the USDA, as well as by major grants from the USDA Specialty Crop Research Initiative, the USDA Crop Protection and Pest Management program, and the National Research Council of Norway.

For additional information, see this Cornell Chronicle story.

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