When growers in the Gulf Citrus Health Management Area in southwest Florida first started coordinating spraying efforts to combat the Asian citrus psyllid, they weren’t sure what the results would be.
But now, after three seasons, they’re hearing some good news.
“Compared to other areas of the state that are behind us in these organized sprays, we have a relatively low incidence of these vectors,” says Mark Colbert, general manager for A. Duda & Sons Inc. in Oviedo.
CHMAs—or citrus health management areas—were recommended in 2010 by a group of scientists from the National Academy of Sciences. The Florida Department of Citrus had commissioned the report to help the industry survive psyllids and avoid citrus greening disease—also known as huanglongbing or HLB—that they spread.
The purpose of CHMAs is to coordinate the timing of psyllid sprays to enhance control beyond what one or a few growers can achieve on their own, says Michael Rogers, citrus Extension entomologist at the University of Florida’s Institute of Food and Agricultural Sciences Citrus Research and Education Center at Lake Alfred.
If one grower sprays and his or her neighbors don’t, the psyllid can simply migrate in from the untreated areas and reinfest the treated grove.
The National Academy of Sciences report also suggests that growers each time all use the same pesticide mode of action for their coordinated sprays to thwart pesticide resistance. Then they all rotate to a different mode of action.
The popularity of CHMAs has risen dramatically, Rogers says. As of early September, 34 CHMAs had been formed throughout the state covering 426,000 acres of commercial citrus groves.
The concept of CHMAs isn’t new. Some growers have been coordinating psyllid control sprays for several years.
Responding to grower requests, University of Florida’s IFAS and the Florida Department of Agriculture and Consumer Services established a formal statewide CHMA program in 2010.
The Gulf CHMA was the first and largest CHMA, covering 100,000 acres, says Phil Stansly, IFAS entomology professor based at the Southwest Florida Research and Education Center in Immokalee.
The Gulf CHMA is different from others in that it’s made up mostly of large-scale growers, Stansly says. It’s also less regimented. “We don’t get into the micromanagement part of it,” Stansly says. “It’s a little easier to reach a consensus that way.”