by BRAD BUCK, UF/IFAS
Florida strawberry growers can use less pesticide and save money as they try to control a mighty pest known as chilli thrips, University of Florida research shows.
An invasive pest in the southeastern United States, chilli thrips was introduced to the United States from Southeast Asia. The first report in Florida came in 1991 in Okeechobee County and then in 1994 in Highlands County.
Sriyanka Lahiri, a UF/IFAS assistant professor of entomology, focuses on the potential damage chilli thrips can cause to Florida’s $500 million-a-year strawberry industry. Strawberries grow mostly in Hillsborough County, but also in Manatee and Polk counties.
In the newly published study, Lahiri and her colleagues found chilli thrips prefer to aggregate in about a 100-meter radius outside the center of strawberry fields. That’s because in the field-border area, chilli thrips are close to adjacent woods, where they can easily live during the summer and reinfest during the next strawberry season.
“Our findings are important to growers as they can now save money and time by having to spray a lower volume of insecticides in smaller portions of their field,” Lahiri says. “They can protect the beneficial insects in and around their field by doing this, which in turn will assist with maintaining more healthy strawberry plants.”
Specifically, growers should spray no closer than 100 meters – or about 330 feet of their field border. They should leave the rest of the field either untreated or manage it by using biological control agents, botanicals and flowering plants.
Field-border pesticide treatments can reduce pesticide use to two to three applications per season, down from the typical six to 10 sprays of the entire field done now, she said.
Additionally, strawberry plants that are treated with insecticides are likely to produce seven times more marketable fruit than those suffering from season-long chilli thrips infestation, Lahiri says.
“To manage the first round of migrating chilli thrips populations, growers will need to use any one of the effective chemical sprays,” saysLahiri, a faculty member at the Gulf Coast Research and Education Center. “Once the initial population has been knocked down to manageable levels, you can use biological control agents such as predatory mites, minute pirate bugs, Beauveria bassiana-based compounds or botanical insecticides such as Captiva Prime and Azera.”
