Can’t get enough cantaloupe? University of Florida scientists want to help farmers in Florida and across the globe grow the cucurbit to satisfy consumers’ tastes.

Even with fungicides, producers struggle to control powdery mildew, a disease that can damage or kill cantaloupe. Thanks to UF/IFAS research, growers may now use ultraviolet (UV) light. Natalia Peres, a UF/IFAS plant pathology professor, has published a new study that shows UV light can zap the pathogen on the plants – without damaging them.

“Powdery mildew is one of the most common and severe diseases of cucurbits worldwide,” said Peres, a faculty member at the UF/IFAS Gulf Coast Research and Education Center (GCREC). “It can be a major disease on cantaloupes grown in Florida, although there are some cultivars that tolerate it better.”

In the Sunshine State, cantaloupe producers are largely in Collier, Hendry, Hardee, Manatee and Hillsborough counties. Florida farmers harvest cantaloupe from mid-March through May. The USDA NASS State Agriculture Overview for Florida shows that the state’s growers harvested 1,500 acres of cantaloupe in 2021. That’s about 375,000 pounds, worth just under $10 million annually. Nationally, growers produced cantaloupes worth $277,503,000 in 2021.

Powdery mildew can survive natural UV light in sunlight. So, the disease can fight the natural UV light of daytime, but not at night.

“If we applied UV light during the day, we would need to use higher doses to get the same effect,” Peres said. “However, these natural defenses are not active at night, so by applying UV light at night, we can bypass the natural defenses of the pathogen and kill it with lower doses that we would need during the day.”

Ueder Lopes, a professor at Universidade Federal do Agreste Pernambuco in Brazil and a project collaborator, harvests cantaloupes.

That’s why scientists put an ultraviolet lamp behind a tractor, drove it onto the GCREC research farm once or twice a week (overnight), pointed the light at the cantaloupe and struck the mildew out of the plant.

“Our unit was built in a shop by one of our strawberry growers,” Peres said. “Similar and bigger units could be designed and built for growers to use at their farms.”

No commercial units are available for field applications – yet, but there is a lot of research recently on the use of UV light in agriculture systems. Peres has already shown the UV light can work to suppress powdery mildew in strawberries, a $300 million annual crop in Florida. Her research using the UV light on strawberries caught the attention of a colleague of hers in Brazil.

She hopes these findings give a ray of hope to cantaloupe farmers across the globe.

“The UV light may be a practical approach to suppress powdery mildew in cantaloupe with the potential to reduce disease severity without damaging the plants or decreasing yield,” Peres said. “We are very limited in the number of types of fungicides available to control this and other diseases. Additionally, pathogens are acquiring resistance to some of these fungicides, so we need alternative methods.”

Included among the researchers who helped Peres with this research were Ueder Lopes, a professor at Universidade Federal do Agreste Pernambuco in Brazil, Galvin Alonzo, a doctoral student in the GCREC plant pathology lab and Gary Vallad, a plant pathology professor at GCREC.