Click for more information on Citrus Health Management Areas, or CHMAs
Cooperative efforts among growers to control the Asian citrus psyllid in 38 regions of Florida are beginning to pay dividends with lower pest populations and newfound hope.
The theory behind citrus health management areas, or CHMAs, is if you reduce psyllid populations, you reduce the potential for them to spread huanglongbing, a deadly citrus disease.
“We have to be encouraged,” says Mike Sparks, president and chief executive officer of Lakeland-based Florida Citrus Mutual.
Nevertheless, he says that many of the control measures, including CHMAs, are stopgap as the industry seeks longer-term, more sustainable, solutions, such as HLB-resistant trees.
Part of Sparks’ job is to educate consumers and buyers that the Florida citrus industry continues to be viable, despite HLB and Asian citrus psyllids.
“We still have 550,000 productive acres and produce nearly 1 billion gallons of orange juice,” he says.
That’s down from 1.3 billion singlestrength equivalent gallons only 10 years ago, according to U.S. Department of Agriculture figures.
Although HLB can be blamed for some of that reduction, Sparks says hurricanes, urban development and citrus canker also took out groves.
Sam Jones, Eastern citrus division operations manager for Duda Farm Fresh Foods, LaBelle, says educating buyers about fresh citrus availability is an on-going effort. to Florida to spend time with us in the groves.”
CHMAs are voluntary efforts among growers within production regions to coordinate citrus pest control measures.
Although CHMAs are formed by growers, they typically seek input from University of Florida citrus experts about what to spray and when.
The theory behind the management areas is if everybody sprays at one time, Asian citrus psyllids can’t seek refuge in nearby untreated groves.
The cooperative spray effort was one of numerous recommendations coming from a strategic plan developed by the National Academy of Sciences in 2010 about how to manage HLB and its vector.
Currently, 38 formal CHMAs cover about 486,000 acres, says Greg Carlton, Florida Department of Agriculture and Consumer Services chief of pest eradication and control in Tallahassee.
In addition, groups of growers along the Atlantic coast coordinate spray efforts, although they haven’t formed formal CHMAs, he says.
The U.S. Department of Agriculture and the Florida Division of Plant Industry in August 2011 began scouting 6,000 grove blocks for psyllids every three weeks. That amounts to about 106,469 acres scouted per cycle.
They report their findings to CHMAs to determine when to treat.
And the efforts are paying off, says Michael Rogers, an entomologist at the Citrus Research and Education Center, Lake Alfred.
He presented a series of maps at the recent Florida Citrus Industry Annual Conference, showing CHMAs and colorcoded psyllid populations.
As the months progressed from August 2011, the populations throughout the citrus belt dropped significantly.
“This is showing that the efforts going on are having an impact on psyllid populations in the state,” Rogers says. “You can’t just attribute it to winter and cold weather.”
Quite the contrary, he says. The 2011-12 winter was warmer than normal so you’d expect higher psyllid numbers appearing earlier in the season, if anything.
The number of groves with no detectable psyllids increased by about 30 percent this year compared to the same time in 2011, Rogers says.
“You can’t call them psyllid-free because there are probably psyllids there, but they’re below detectable levels,” he says.
As growers quit spraying in February, March and April to protect bees during bloom, the maps showed psyllid numbers rebounded, but not to the numbers they were when monitoring first started in 2011.
Rogers also pointed out that abandoned groves, which go untreated and can harbor psyllid populations, can cause hotspots in otherwise vigilant CHMAs.
Attracted by the flush of managed groves, psyllids can fly up to 1.25 miles from abandoned groves, says Lukasz Stelinski, an entomologist at the Citrus Research and Education Center in Lake Alfred, citing research.
And that’s 1.25 miles of jumping over lakes, fallow fields and other areas without citrus.
“They’re on the move to find resources, and once they find those resources, they’ll stick around and exploit them,” he says. In laboratory trials, Stelinski says he and colleagues found psyllids can fly 50 minutes—or 1 mile—without stopping to rest.