Fewer Pesticides Please

University of Florida scientists believe they’ve found a solution for strawberry growers to control chilli thrips.

Florida strawberry growers can reduce pesticide usage and save money while controlling the significant pest known as chilli thrips, according to research from the University of Florida.

Chilli thrips, an invasive pest from Southeast Asia, first appeared in the southeastern United States in 1991, with initial reports in Florida’s Okeechobee County and later in Highlands County in 1994.

Sriyanka Lahiri in a Gulf Coast Research and Education Center strawberry field. Courtesy, UF/IFAS.

Sriyanka Lahiri, a UF/IFAS assistant professor of entomology, studies the potential damage chilli thrips can inflict on Florida’s $500 million-a-year strawberry industry, primarily concentrated in Hillsborough County, but also present in Manatee and Polk counties.

In a newly published study, Lahiri and her colleagues discovered that chilli thrips tend to gather within a 100-meter radius outside the center of strawberry fields. This area, close to adjacent woods, allows the thrips to live during the summer and reinfest the fields in 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 said in a recent UF news release. “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, Lahiri recommends that growers should spray no closer than 100 meters (about 330 feet) from their field border. The rest of the field can be left untreated or managed using biological control agents, botanicals, and flowering plants.

Field-border pesticide treatments can reduce pesticide applications to two or three per season, compared to the current six to ten sprays across the entire field. Additionally, strawberry plants treated with insecticides are likely to produce seven times more marketable fruit than those infested by chilli thrips throughout the season.

“To manage the first round of migrating chilli thrips populations, growers will need to use any one of the effective chemical sprays,” said Lahiri, who works 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 like Captiva Prime and Azera.”

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