Workshop Provides Black Spot Advice

Ernie Neff Diseases

Orange infected with citrus black spot
(Photo by Megan Dewdney, UF/IFAS)

Information to help growers find and control citrus black spot (CBS), as well as CBS regulatory procedures, were provided in an Oct. 26 training workshop in Arcadia. The workshop was hosted by multi-county citrus Extension agent Ajia Paolillo.

University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) plant pathologist Megan Dewdney discussed the pest’s lifecycle, potential spread due to storms, and scouting techniques to use in the grove. She said the spores of CBS are found on dead twigs, leaf litter and in the lesions found on fruit. The spores move mostly through water, including rain splash, but are moved through wind-driven rain as well. This disease has been found in five southwest Florida counties and has the potential to move north through the citrus-growing region.

Dewdney said this is the time of year when most symptoms become visible once fruit starts to change color and mature. Four types of symptoms can be expressed with CBS: hard spot, virulent spot, false melanose and crack spot. The use of fungicides can control CBS, leading to less disease symptom expression and inoculum.   

Callie Walker discussed the regulatory procedures associated with a CBS find and quarantine area. She is chief of the Bureau of Pest Eradication and Control for the Florida Department of Agriculture and Consumer Services (FDACS) and state director for the Citrus Health Response Program (CHRP).

There are currently quarantine areas in five counties: Charlotte, Collier, Hendry, Glades and Lee. Prior to and during harvest season, CHRP conducts surveys of citrus groves to look for symptoms of CBS, Walker said. The CBS survey area covers a 10-mile arc, which is determined using current positive CBS locations. Although there have been no positive finds of CBS in DeSoto and Highlands counties, parts of these counties do fall within that 10-mile arc. Positive finds are tracked using GPS and verified using the FDACS lab in Gainesville and the U.S. Department of Agriculture lab in Maryland. Growers in the area are notified of positive finds and the quarantine.

Growers in quarantine areas must tarp all loads of harvested fruit when hauling to the juice plant or packinghouse. Processors and packinghouses follow strict procedures for handling these loads and disinfecting the trailers before they are used again to help prevent spread of the disease. 

More information about CBS can be found in the 2021-22 Florida Citrus Production Guide and at the FDACS website.

Source: UF/IFAS

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