Hurricane Irma Raises Black Spot Threat

Ernie Neffblack spot, Diseases

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black spot
Orange infected with citrus black spot
(Photo by Megan Dewdney)

University of Florida Institute of Food and Agricultural Sciences Extension pathologist and associate professor Megan Dewdney reported that U.S. Department of Agriculture (USDA) scientist Tim Gottwald thinks there’s a “fairly high” chance that Hurricane Irma spread citrus black spot. Black spot had been confined primarily to Southwest Florida, especially Collier and Hendry counties, before Irma hit the state with damaging winds in the fall of 2017.

“Of course it’s going to take us four to five years from now to see whether he (Gottwald) is correct or not,” Dewdney said. “But it is something that people should be cognizant of, especially if they are down in the Gulf Coast region and don’t have the disease already in their groves.” 

Dewdney suggested that growers, particularly those outside of the Gulf Coast region, learn the symptoms of black spot and scout for the disease. “One of the best protections against any disease is to know what you have and be able to then take action,” she advised. “If you don’t know it’s there, then you can’t do anything about it.”

Control measures for black spot include alternating copper and strobilurins.

“I know people have not taken black spot seriously over the years in areas outside of Southwest Florida, but it’s something that we shouldn’t just ignore,” Dewdney concluded.

She discussed black spot and other citrus diseases at a seminar earlier this year in Immokalee. The seminar was hosted by multi-county citrus Extension agent Mongi Zekri at the Southwest Florida Research and Education Center.

Hear more from Dewdney:

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Ernie Neff

Ernie Neff

Senior Correspondent at Large