Citrus Black Spot Spreads in Polk County

Josh McGillDiseases

Citrus black spot (CBS) disease was confirmed at a second location in Florida’s Polk County in March. The new find was in a grove near State Road 60 and Indian Lake Estates, east of Lake Wales.

Polk County

The only prior CBS infestation in Polk County was near U.S. 27 on the Highlands County border. But that location was turned into an industrial site several years ago, according to University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) plant pathologist Megan Dewdney.

Other than Polk County, citrus black spot has been found only in five counties in Southwest Florida, primarily Collier and Hendry, for several years.

In a May 17 CBS presentation at the UF/IFAS Citrus Research and Education Center in Lake Alfred, Dewdney raised the possibility that 2022’s Hurricane Ian could have spread CBS beyond known infestation locations. She said the effects of Ian are uncertain but noted that the hurricane passed through areas with CBS. The best policy is to be vigilant in managing the disease, she emphasized. 

CBS can cause up to 60% yield loss due to fruit drop in severe situations with little management, Dewdney said. More commonly, fruit drop reaches 10% to 20% in minimally managed groves, she reported. Fresh fruit coming from CBS-infected areas can face export restrictions to certain destinations, especially the European Union.

Dewdney’s management recommendations include:

  • Determine if CBS is in your area or grove.
  • Use a multiple mode-of-action fungicide program for resistance management. Use copper in the program as an alternation.
  • Manage leaf litter to enhance the effect of the fungicide program.
  • Remove as much dead wood as possible and destroy it on site.
  • Practice vehicle and equipment decontamination when leaving affected sites.

“If you reduce or eliminate a CBS management program, disease will return,” Dewdney concluded.  

Learn more about management of CBS in Florida.

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About the Author

Ernie Neff

Senior Correspondent at Large

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